Tuesday 23 June 2015

Wet-Sanding (Colour Sanding)


Skill Level / Experience
This kind of work should only be undertaken by a professional or hobbyist detailer; who is experienced in colour-sanding (wet-sanding) / paint renovation, more so than detailing, someone who uses a paint thickness gauge (PTG) to measure and document the vehicles paint as this is a technique is capable of removing  ~ 2.5 – 7.5 µ (microns) > 0.1 to 0.3 Mil of clear coat

Results will vary depending on your ability and the thickness of the factory finish. Wet-sanding (colour-sanding) a complete vehicle body may be beyond the capabilities of the average detailer or enthusiast; in this case we strongly encourage the reader to consult a professional detailer. Correct wet-sanding takes a lot of experience and practice to perfect. This statement is not meant to question anything related to your detailing or paint re- finishing abilities just my opinion on the risks involved

Some methods described may be beyond the capabilities of the average detailer or enthusiast; in this case we strongly encourage the reader to consult a professional detailer or body shop concerning the matters discussed herein. The writer assumes no responsibility, expressed or implied, due to misuse or misinterpretation of the information or methods used, or for any vehicle damage or injury that may occur due to the suggestions and information offered.

Focusing on one person’s methodologies or the products or tools they use will seriously limit your detailing experience and knowledge. Most importantly - choose carefully whose advice you listen to, and more importantly what advice you act upon.

How to tell if the paint needs sanding or compounding would be dependent upon what the vehicle is used for and you’re detailing goals for it. The use of a paint thickness gauge (PTG) is considered mandatory when wet-sanding

a)        Factory paint on a daily driver probably wouldn’t be a good candidate, OEM paint is very thin and constantly removing scratches will compromise its ultra violet (UV) protection necessitating a re-paint

b)       Concours d’élégance vehicle preparation while it's important to try to remove as many of the defects as possible you are still limited by the thickness of the clear coat or colour  paint of a single stage paint system. Originality is an important consideration with this type of vehicle.
I would only wet-sand freshly painted or custom paint cars and strongly advise against wet-sanding OEM paint finishes, as the paint is usually very thin, or  wet-sanding any paint without first using a paint thickness gauge (PTG) to check the thickness of available clear coat; consider < 110µ ( microns) the very minimum
Be cognizant that wet-sanding removes paint, you're then going to have to compound and finish polish, these procedure will also remove paint, so it's vitally important that you are working on a custom paint job or you have sufficient paint thickness, experience, skill and confidence to wet-sand a factory finish.
Wet-sanding is the most efficient method of ‘levelling’ a paint surface. When you use finishing paper and a sanding block, any uneven paint or ‘high spots’ will be  levelled as the abrasives in the finishing paper are focussed by the applied pressure and the flat shape of the sanding block, which  removes  material far more evenly until the surface becomes level
Using a baking plate, pad and an abrasive polish you are applying pressure over the ‘soft’ baking plate that will follow the contours or high spots
Practice on something expendable; as it takes a lot of practice to do correctly; and there is a very small margin of error, which results in an expensive e-paint
Before you wet-sand and polish any OEM finish, you should know this will void the paint warranty if you remove more than 0.3Mil (7.5 µ (micron) as this will negatively impact the paint systems ultra violet (UV) protection.

The following are the maximum allowable clear coat reductions the major USA car manufacturers will allow before the paint warranty becomes void;  latest (2014) technical service bulletin TSB) state 0.3 Mil (7.5 µ) maximum clear coat removal

Block wet sanding (finishing paper and a sanding block) is the most effective tool for paint defect removal; because of its linear process you abrade the paint surface flat until the defects are removed.  Wet-sand with Trizact 1500 grit, which will level the surface and then use 3000 grit to remove 1500 scratches the paint, will have a semi-gloss before the final polish / buffing even starts.

Finishing paper (sandpaper)
In its manufacture the crystals are electrically charged so that they will stand up. They are locked into a hard resin and when you apply the paper to a surface it will remove the substrate of the material you are sanding. The crystals cut in a negative raking motion, leaving inconsistent scratch patterns. Finishing paper is the most common item from a larger group of products known as "coated abrasives" i.e. Aluminium oxide. Finishing paper is available in a variety of abrasives or grit numbers i.e. 1000, 1500, 2000, 2500, and 3000 

Its "grit" rating is a reference to the number of abrasive particles per inch of paper. It eliminates the risk of deep sanding scratches by providing a uniform grit size. This makes sense if you imagine how small the grit particles on a 1000-grit finishing paper would need to be to fit into a 1- inch square.
Grit finishing paper is referred to by the size of its abrasives (i.e. 2000-grit paper) the grit you use depends on to what degree you want to polish or refine a surface. 1500 grit finishing paper abrades the (freshly painted) surface level and then the 3000 grit removes the 1500 scratches

Micro-Surface Finishing Products, Micro-Mesh™ - (use Ultra-Flex Micro-Mesh™ Aluminium Oxide for finishing aluminum). These non-abrasive abrasives are considered a cushioned abrasive in fact. Conventional sandpaper or finishing paper is designed to be aggressive so that it will dig deeply.
In its manufacture the crystals are electrically charged so that they will stand up. They are locked into a hard resin and when you apply the paper to a surface it will literally tear in and remove the substrate of the material you are sanding. The crystals cut in a negative raking motion, leaving inconsistent scratch patterns.

Micro-Mesh™ does the opposite. The backing is long lasting cloth to which an ultra-flexible cushioning layer is applied. This cushioning layer will determine how far forward you can push crystals before they will penetrate the cushioning layer.

On top of this layer, we have very resilient glue, not a hard resin, but completely flexible glue that will hold the crystals while allowing it to move and rotate. The crystals can turn in any direction without coming loose. When you start to apply pressure to sand with Micro-Mesh™, the crystals will go into the cushioning layer while beginning to cut a bit.

If you push harder, they will go further into the cushioning layer, which serves as a safety valve. It determines how much pressure you can exert in a down ward direction.
Instead of a deep scratch that sandpaper makes, Micro-Mesh™ produce a refined scratch that is close to a RMS of 1.0. the abrasives are made with large, very uniform crystals that recede into the Ultra-Flex matrix as pressure is applied, allowing the crystal tips to all line up so they are level with the part being polished. This technology provides a more brilliant, consistent finish.

The cushioning layer also allows the crystals to cut with a planeing motion that leaves an extremely consistent scratch pattern and allows you to achieve extraordinary levels of gloss. Where conventional abrasives will take surfaces down to 51-76µ, Micro-Mesh™ will take it down to2.5µ or less

Damp sanding

Simply a variation of wet sanding (colour-sanding) except that you use less water and sanding discs designed for use with this process. The water on the surface suspends particles of paint removed off the surface from the abrading action of your sanding disc, because it utilizes less water for the process this equates to less clean-up of the work area. I’ve always preferred air tools for sanding as they generally have less torque than electric tools, which affords better control.

3M™ Trizact P1500  Foam Discs – (ultra-fine 1500 grit)   allows you to level more serious defects and then the 3000 grit removes the 1500 scratch, leaving a semi-gloss finish , which may save the ultra-thin coating found on PPG's  DuPont's SupraShield™,  Optech™ and CeramiClear™ as they  use an ultra-thin layer of ceramic clear coat over the regular clear coat.

These ultra-fine papers allow you to level serious defects without removing too much of this ultra-thin final coating. The 3M Trizact P5000 (grit) Foam Discs are available in three sizes: 3, 5 and 6- inch.

Foam Interface Pad
Use of a foam interface pad between the sanding disc and the backing plate is recommended. A foam interface pad is made to improve your results during sanding, refinishing and spot repair projects. The foam pad improves the sanding disc's ability to follow the curves and contours of a vehicle.
The foam interface pad makes machine sanding smoother for the technician and enables the sanding disc to conform better to curved body panels. Using an interface pad also reduces the aggressiveness of the sanding action and reduces the chance of creating coarser scratches.

New Abrasive Technology
These ultra-fine cut finishing discs are made from a Silicon Carbide Mineral embedded in a cured resin medium on a flexible film. The polyurethane foam backing is designed for wet use. 3M Trizact 5000 Discs should only be used with water for both machine and hand sanding.

Colour Sanding (Wet-sanding)  

Years ago it was called colour sanding because automotive paints were single-stage (primer and a colour coat) and when the finish faded from ultra violet radiation (UV-B) exposure, sanding off the oxidized paint thereby exposing the underlying paint would bring back the paint surface colour.
Re-painted panels can be wet-sanded after 48 hours (check P-Sheet), however a good rule of thumb for most paint systems is to wait for about 72 hours (max 7-14 days) subject to climatic conditions
Clear coat paint in combination with the basecoat forms the automotive topcoat, which gives the vehicle its appearance. One and two component clear coats (1K and 2K) are applied over both solvent and water-based basecoats. Now most detailers refer to it as wet-sanding as opposed to colour sanding

Then, as now, most sanding was done wet so the terms colour sanding, wet sanding and as all these process involves a sanding block, block sanding all became interchangeable whether you were sanding to restore single stage (BC) colour or to level the surface of a clear coat (BC_CC) paint system to remove surface imperfections.

Block wet- sanding (finishing paper and a sanding block) is considered the most efficient form of paint correction, by ensuring a consistent pressure over the entire surface contact area and using a long stroke; this is the most effective tool for paint defect removal because of its linear process you abrade the paint surface flat until the defects are removed and a perfectly ‘flat’ levelled surface is obtained. This provides an optimum surface light reflection / refraction (in simple terms the light reflectance from a mirror)

I am never too keen to colour sand factory paint, but any aftermarket paint is a great candidate. Don't start with less than 1500 grit finishing paper unless you have lots of material to work with or some serious imperfections.

Wet-sand with 1500-2000 grit finishing paper and then use a 3000 grit foam pad and an orbital polisher to level the paint surface, this will ensure a ‘perfectly’ smooth paint surface.
Block wet sanding (finishing paper and a sanding block) is the most effective tool for paint defect removal only because you can sand the paint surface flat until the defects are removed.  Non- diminishing abrasives and a flat foam pad are similar in application.  

Sanding a paint surface is a very labour intensive way to eliminate orange peel or other paint surface problems; this method can take an entire day to sand a vehicle properly. Sanding can be done by hand using 1500, 2000 or 2500 grit finishing paper and sanding with a palm sander can be done with Finishing Film or 3M™ Trizact.

Wet-sanding isn't something to be afraid of, providing you use the correct products and methodologies; but it is a process that is very aggressive and should be used with common sense and sufficient caution. I usually recommend 3M™ Finishing Film for the inexperienced paint renovator using a palm sanders because it is less expensive and can be used dry so that you can see the results of your effort while you're sanding so you can see exactly what you are doing. Trizact is used wet and goes much further than the Finishing Film but you need to wipe the surface and remove the slurry to check your progress.

 Made out of high impact ABS plastic and it’s constructed in an ergonomic shape for complete comfort when sanding. The tough rubber pad that is firm for wet or dry use. Perfect for wet sanding as it's made from stainless steel and plastic and it floats in a bucket. It also has the best paper clamping system I've ever experienced and it's flat.
·         High-impact ABS plastic, tough rubber pad that is firm for wet or dry use.
·         Ergonomic shape for complete comfort when sanding.
·         Stainless steel lever action clips to grip & pull the sandpaper tight.
·         Tapered edges allow you to get into corners
·         2-34"W x 7-3/4"

Paint Removed by Wet-Sanding
When removing deep scratches wet-sanding will remove less paint than a rotary polisher and a diminishing abrasive, however using a non-diminishing abrasive would remove more paint (there are many variables involved with the above hypothesis-pressure, speed RPM, linear motion, and etc.)

Using a medium abrasive grit finishing paper and backing block will remove approximately technique is capable of removing ~ 2.5 – 5.0 µ (microns) > 0.1 to 0.2 Mil of clear coat; but there are many variables such as the abrasive grade of the polish or compound and speed and pressure used, the density (hardness) of the paint and etc. that may affect the amount of paint removed
These numbers should be checked with a paint thickness gauge (PTG) at some point the remaining clear coat numbers, not the repair itself will tell you that you need to stop sanding.

Clear coat breakthrough can happen very quickly, so check periodically, knowing how much clear coat remains is extremely important. There comes a point when you must judge wither removing a scratch will compromise the clear coat and if so you’ll have to ‘live’ with the imperfection.
A paint thickness reading of 100 µ (Microns) is reasonably safe for wet-sanding 80-90 µ I wouldn't use anything stronger than > 2000 grit, 70-80 µ > 2500 grit and under 70 µ I would recommend the use of a glaze. The readings tend to vary from panel to panel and are thinner towards the panel edges.
If you have reservations about the amount of paint surface removed or the amount of paint coating remaining the use of a paint thickness gauge (PTG) is arbitrary

These numbers are offered as a guide only, as there are too many variables to provide any more than an approximation.

Note: 1 µ (micron) is 1/1000th of a millimetre or 0.0393700787 Mil or 0.001 of an inch
·         200µ + can be expected on older cars that have been hand painted or a re-painted vehicle
·         100 – 200µ 4 – 8 mil - normal paint thickness
·         80 – 100 µ - 3 – 4 mils, thin paint
·         80 µ < - less than 3 mil, very thin paint

Speed
Pad velocity at an identical RPM; V = RPM (Area) A - 6.5-inch = 20.423 sq.ins V= 24,507 inches per minute (IPM) Pad velocity is also substantially increased with a larger diameter pad,

Clear Coat Thickness

A micron (µ) is a metric unit that equals one millionth of a meter, or 1/1000 of a millimetre. A micron is much smaller than a Mil. There are 25.4 millimetres in an inch and a micron is 1/1000 of a millimetre. Using the micron measurement gives you a much better idea of paint thickness because it's so much smaller.

The clear coat provides gloss plus physical protection from the elements, including ultraviolet (UV) radiation, which is in the upper level of a cured clear coat, removing more than 12.5µ of clear coat will precipitate premature paint film failure.

There is ultra violet (UV) protection all the way through the paint, but the majority of it migrates to the top ~15-22µ of cross-linked clear coat along with the thinner solvents and particles.
Therefore removing clear coat ultra violet protection is not a linear process; by removing a small percentage of the clear coat paint tends to remove a larger percentage of the ultra violet (UV) inhibitors.

So once you remove too much clear coat you'll have no paint UV protection other than what you apply with a LSP (providing it contains UV protection

Modern clear coat paint finishes are so good today that they lull people into thinking that vehicle paint has protection and shine when in reality there is not really much there, other than the clear coat that has a thickness of ~25.4 µ. As a point of reference a sheet of copy paper is 89 µ.  One (µ) micron is roughly 1/80th of the thickness of a human hair

Most car manufacturers will only allow ~ 25% of the clear-coat thickness to be removed without voiding the paint warranty and long-term durability problems becoming an issue. That means that if you started off with 50µ of clear coat, you would only be able to remove < 12.5µ without voiding the paint warranty and possibly having a re-paint.

Be cognizant that wet-sanding can remove > 12.5µ very quickly. Two variables need to be established; (1) How much clear coat is available (2) how much clear coat can be removed without compromising long-term durability

Paint thickness gauge

Taking constant paint thickness measurements during the wet-sanding process will ensure against removing too much paint. A PosiTest DFT Combo, measures paint on any metal; including steel and aluminium, a popular choice given many cars have both steel and aluminium. It automatically recognizes the material and takes a measurement

Sanding Prep

Wash paint surface thoroughly to remove any surface contamination, fill a spray bottle with paint cleaner/ degreaser (DuPont PrepSol II™ to remove old wax and soluble contaminates, spray onto a 100% cotton micro fibre towel (DF Towels - DF Concours products) and clean the surface. If you don’t wipe the surface before you sand you will not remove the contaminants, you will force (sand) them into the paint surface

The secret to a Concours d’élégance winning paint finish is colour-sanding (before wet-sanding paint show vehicle owners often have an extra 2.5 Mil to 3.0 Mil of clear applied).
The paint sections / panels that are difficult and involve risk are usually those that are close to the edges of a panel (as this is where the paint is usually thinnest) or highly contoured areas. Flat areas like the trunk, hood or roof involve minimal risk.

Orange peel

It is possible to wet-sand orange peel, but if you try to eliminate it completely you risk severely compromising the paint thickness.

Wet-sanding levels the paint (and removes orange peel, harsh acidic or alkaline marks, etc.) it removes approximately 0. 1 Mil ( Microns) of paint from the vehicle using 2000 -grit finishing paper.  A digital paint thickness gauge will allow you to measure the film thickness of the paint system which includes the e-coat, primer, base coat (colour) and clear

Be cognizant that orange peel is found on both OEM and re-painted vehicles. Modern Isocyanate resins (clear coat) finishes are so good today that they lull people into thinking that vehicle paint has protection and shine when in reality there is not really much there, the clear coat that has a thickness of ~25.4 µ (micron). As a point of reference a sheet of copy paper is 89 µ

The clear coat provides gloss plus physical protection from the elements, including ultraviolet (UV) radiation, which is in the upper level of a cured clear coat. Most car manufacturers will only allow ~ 25% of the clear-coat thickness to be removed without voiding the paint warranty and long-term durability problems becoming an issue.

That means that if you started off with 50µ of clear coat (this will vary by vehicle manufacturer) you would only be able to remove <12µ without voiding the paint warranty and possibly having a re-paint.
Removing clear coat ultra violet protection is not a linear process; by removing a small percentage of the clear coat paint tends to remove a larger percentage of the ultra violet (UV) inhibitors.

Defect removal – these pads are also very effective when used for defect removal without flattening out paint provided they are used with a soft flexible baking plate. Using the same principle behind wet sanding; it’s dependent upon the baking plate used i.e. a stiff baking plate (block sanding) is used to level paint, whereas a soft baking plate will remove defects

You should initially try these on a test panel and get an idea of just how fast they remove paint. Using little or no pressure (machine weight alone) start a low 600-700 RPM and then progress to 1200 RPM, at this speed the kinetic heat produced by these pads  is high so it is wise to constantly check paint surface temperature. The pad / backing plate combination is rigid an so acts in a similar way to 'block sanding’, removing the high spots before the valleys, maintain the pad flat and parallel to the surface; a spritz of distilled water can be used to reduce the surface temperature, but beware of product spatter

CarPro Orange Peel Removal Pads - you can now remove or substantially reduce orange peel in the top layer without sanding. While removing orange peel and deep defects you are also polishing the paint rather than leaving sanding marks, which reduces the steps needed afterwards.

These pads have a very aggressive abrasive and are deceptive; they have twice the rate of cut of typical wool pads. They don't dull the paint like sanding so it may appear you aren't removing paint but you most certainly are.

They are intended for use by professionals who are very familiar with paint film thickness, using and interpreting the results of a paint thickness gauge (PTG) compounding, polishing, and the dos and don’ts of paint correction. Theses pads are designed for use with a rotary polisher (1000 RPM <) average removal is approximately 5µ (0 .2Mil) - 7.5µ (0. 3 Mil)

These pads are available in two configurations: Denim (2000 Grit) is the more aggressive and designed for the removal of severe texture from refinished paints and Velvet (3000 Grit) is used for removing light orange peel from thin, factory-applied paint; both pads  utilizing CarPro Fixer as a lubrication / compound. 

Use very little pressure and check the paint surface temperature often. Similar to ‘block sanding’ the pad / backing plate are rigid enough that when used correctly it abrades the paint ridges (high spots) faster than the valleys. Either pad will polish the paint as it removes orange peel requiring only one or two additional polishing steps to create level paint that reflects accurately. These pads should only be used with proper knowledge of clear coat thickness in conjunction with a paint thickness gauge.  As with any aggressive abrasion method be very cautious with factory OEM paint.

There are two considerations; (a) how much clear coat (b) how much ultra violet protection can be removed, they are not interchangeable. The following are the maximum allowable clear coat reductions the major USA car manufacturers will allow before the paint warranty becomes void; The following are the maximum allowable clear coat reductions the major USA car manufacturers will allow before the paint warranty becomes void;  latest (2014) technical service bulletin TSB) state 0.3 Mil (7.5 µ) maximum clear coat removal

Wet or Dry Sanding

Either is a safe option as there is no risk of electric shock risk as you’re not mixing water / electrical current. If possible, it is always better to use a lubricant. This will extend the life of the finishing paper greatly and keep the material from loading. It will also keep heat generation to a minimum.
There are many types of lubricants, but generally water is best. It is best to work using a light mist or spray. Flooding the work surface or work piece is not recommended as it will cause the abrasive to aquaplane  across the surface, making less surface contact and removing less material

3M™ Trizact P5000  Foam Discs – (ultra-fine 5000 grit) they  allow you to level more serious defects , which may save the ultra-thin coating found on PPG's  DuPont's SupraShield™,  Optech™ and CeramiClear™ as they  use an ultra-thin layer of ceramic clear coat over the regular clear coat.

These ultra-fine papers allow you to level serious defects without removing too much of this ultra-thin final coating. The 3M Trizact P5000 (grit) Foam Discs are available in three sizes: 3, 5 and 6- inch.

Foam Interface Pad
Use of a foam interface pad between the sanding disc and the backing plate is recommended. A foam interface pad is made to improve your results during sanding, refinishing and spot repair projects. The foam pad improves the sanding disc's ability to follow the curves and contours of a vehicle.
The foam interface pad makes machine sanding smoother for the technician and enables the sanding disc to conform better to curved body panels. Using an interface pad also reduces the aggressiveness of the sanding action and reduces the chance of creating coarser scratches.

The 3M Random Orbital 6 Inch Air Sander is designed to leave a smooth finish without over-sanding any particular spot. The abrasive disc and disc pad on this dual action sander move in two distinct oval patterns. No single abrasive particle follows the same path twice. Therefore, the results are smooth and even across the entire sanded area, whether it's a small spot or an entire panel
.
3M Random Orbital 6 Inch Air Sander

The Air Sander has a 3/16- inch orbit, which is rated for general purpose sanding. A Stikit™ Low Profile Disc Pad is included with the sander. Use 1500, 2000 and 3000 grit Trizact sandpaper used wet to level the paint then a rotary polisher and a foam pad to produce a gloss finish. Check out the selection of 3M sanding and finishing discs for more disc options

Wipe down Process
Anhydrous Isopropyl alcohol [Molecular formula C3H8O] for all-purpose cleaning, isopropyl alcohol, is a colourless liquid with a pleasant odour, and is highly flammable.

Isopropyl alcohol also known as IPA, is excellent for removing oils / grease from paintwork before applying your final sealant or wax after polishing, or used  to clean stone chips before painting. Wiping the finish with a micro fibre cloth you may feel that the swirls have been removed, only to have them reappear when applying the final wax or sealant. After polishing a section, mist and wipe to fully remove residues and reveal the true paint finish.

a)        Polymer sealants will not form a proper monocular bond with a paint surface if there are any silicone or synthetic oils present, they will also affect durability if not removed
b)       Silicone will cause surface smearing and will affect abrasives effectiveness, product  bonding and durability (See also Silicone Removal)

A wipe down after polishing or compounding is used to remove the carrier oils and wax used for surface lubrication and allows you to inspect the surface to determine if the surface is defect free or if further work is required. When polishing or compounding to remove fine swirls or holograms, it's easy for residues and / or waxes or oils to settle in the swirls, hiding the true paint finish (drop back). Be aware that you may need to repeat this process more than once, perhaps 3-4 times may be necessary. 

The effectiveness of this process is dependent upon a few factors; strength of product used, surface temp of paint, pressure applied and number of passes will all affect the outcome.
The wipe down process should be carried out both before to ensure a surface that is free of any debris and after to ensure that defects have been removed as opposed to masked by any lubrication oils or fillers left behind after the polishing process. The wipe-down process may need to be repeated to ensure a perfectly ‘clean’, debris free surface

Application methodology - Isopropyl alcohol (IPA) if used undiluted it flash dries (evaporates) rapidly, which lessens surface inspection time and will also redeposit the oils you're trying to remove. Alcohol and water will emulsify any oils, enabling them to be removed
 Fill a fine misting spray bottle with an 8:1 ratio of (IPA) / distilled water solution. Spray the surface you have just polished and allow the solution sit for approximately 15 seconds. If it flashes too quickly (hot surface or environment) use further dilution

Agitate the area with a clean, soft 100% cotton micro fibre towel (you may need to repeat this process) change the towel to a fresh quarter after each panel to ensure oil and debris are not re-deposited and observe. What you have done is remove any silicone, wax, and oils that may have filled any remaining swirls.

Now using your surface inspection light, shine the light directly on the panel and look for fine swirls. If they are still present, you should be able to see them. If not you will see a clear bright reflection from the panel with a great shine, and clarity

Notes:
1.        For ‘hard’ clear coat use a very light dilution rate, for ‘soft’ clear coats use a heavier dilution
2.        After the paint surface has been subjected to a chemical cleaning its protective layer (s)  have been removed and the paint surface left without protection, so it is very important that a wax or polymer protection  be applied immediately.

Alternative products
·         Menzerna Top Inspection (PP95) – use to inspect your work, use this water-based cleaner that removes dust left by compounding and any lubricating oils so you can see the real results of your work. There are no silicones or fillers, just gentle cleaning agents to uncover the real condition of your vehicle’s paint.
·         Hi-Temp's Prep Wash - to prepare a paint surface for polishing, compounding, wax and / or polymer sealant application (especially if changing from a wax to a polymer product) this is a water-based paint cleaner designed to remove all traces of silicone, oil, and buffing residue from any exterior paint surface
·         DuPont PrepSol II™ - http://www.xurex.com/products.html) spray onto a 100% cotton or a micro fibre towel and clean the surface
·         Optimum Power Clean - Optimum Power Clean™ is an environmentally friendly, all surface-safe cleaner, used for paint dilute it 2:1
·         Wurth Clean Solve is a fast acting cleaner and solvent that will not leave a film residue. It will quickly remove wax, tar, gum, grease, paint overspray, adhesive, oil, and silicone. It can be used on a variety of surfaces including: base coat, clear coat, aluminium, fibreglass, glass, fabrics and vinyl.
·         Rohm and Haas Acrysol - a high purity solvent for cleaning a variety of surfaces, dissolves excess adhesives, sealers, tar, undercoating, road oil, waxes and silicone polishes.
No residues; cleans thoroughly without leaving an oily film to attract dust and dirt; can be applied to all types of cured paint or unpainted surfaces without streaking or etching.

Methodology
1.        Put a drop or two of Woolite® liquid in a clean bucket and fill it with clean water.
2.        You will need 6-inch x 4-inch sheets of Nikkens™ 2000, 2500 and 3000 - grit finishing paper (1000 and 1500 grit is also available, but they are usually used on single stage paint systems, you can start with any grade of finishing paper according to the condition of your paint film surface, but as always use the least abrasive first) next cut or tear three or four pieces of the finishing papers in half and place them in the bucket also.
3.        Leave them in the bucket of water for about 20 -30 minutes to soften their edges. These papers have a latex rubber impregnated paper backing that is waterproof and this prevents the finishing paper from breaking-down into pulp from over soaking. Keep the surface wet at all times and sand in short strokes, applying light to moderate pressure with the sanding block held flat. After going over the finish with 2000- proceed to 2500- and then switch to 3000-grit finishing paper and sand once more.
4.        While you're waiting for the paper to soften, wash your vehicle too completely to remove any grit or dust, and then gently dry it with clean terry cloth towels. Next, take a tack rag and wipe over the paint surfaces one final time to make sure the paint is absolutely clean. A small particle of grit can make deep scratches in even the hardest finish. If you're working outdoors, wet down the surrounding area to keep dust under control, and keep a garden hose running with a trickle of water on the surface at all times.
5.        Use Gloss It EVP Pad Prime for surface lubrication
6.        Wrap a piece of the softened Nikkens™ 2000 - grit finishing paper (or whatever grade your paint surface requires) around a Unigrit Sanding Block (see also alternative products) if you're going to be working broad, flat surfaces. Otherwise, you can just fold the sandpaper in thirds. Keep wetting the surface of the vehicle in the area where you're sanding and keep it wet while you work. Place your hand flat on the sanding block / finishing paper at all times and start sanding in short, crisscross strokes.
7.        Don’t apply too much pressure to the sanding block; by flexing the metal you’ll sand through the clear on the spots contacting the block before the low spots disappear.
8.        Avoid applying excessive pressure; by flexing the metal you’ll sand through the clear on the spots contacting the block before the low spots disappear.
9.        Always keep the sanding block flat or you’ll gouge the paint surface and never sand with just your fingertips, as you'll create grooves if you do.
10.     Only move the finishing paper and block about 4 - inches back and forth, if you do make a scratch, it will be a short one and easier to buff out. Using shorter, quicker strokes requires about the same amount of time as the longer sweeps most people are used to. Besides, you shouldn't worry about time and have a lot of patient when colour-sanding.
11.     As the finishing paper skims over the surface it will remove the highest points in the paint, causing them to dull, the lower spots will still have a shine; once the high spots have been removed keep working until the paint is level.
12.     Keep the finishing paper surface clean and use a small nail brush to clean any dust ‘pills’ from the finishing papers surfacer; this will avoid any Q type pig tails. The pills will indicate that the paper is almost ready for change
13.     Regularly lift the finishing paper and tap the sanding block with your hand to remove any dust build up.
14.     A clean rubber squeegee (3M™ Wetordry™ Rubber Squeegee, P/N 05517, 2 -inches x 4 -inches) is the best tool for checking your progress. Swipe the squeegee across the sanded surface periodically to clear it of water. Only when you have the surface completely free of any suggestion of orange peel or imperfections are you ready for the next step.
15.     Proceed to the next level of grit and repeat the process until all the coarser scratches are eliminated and finish with 3000 - grit finishing paper in order to remove all of the very fine scratches, only when the paint has a consistently level, smooth, satin finish should you continue to the polishing stage.
16.     By finishing with 2000 – 3000 grit finishing paper, less buffing will be needed to get a flawless finish.
17.     Proceed to remove sanding scratches with a machine polisher, appropriate polish (Menzerna PO 203 Power Finish a 2000 grit polish) and Lake Country (LC) Mfg. Orange or a Green foam pad
18.     Typically the final step in surface polishing; using a finishing polish (Menzerna Final Finish Polish / Super Finish 106FA) in tandem with a pad that has no abrasive abilities (LC) CCS Gold Concours Finishing foam) you are just effectively burnishing the paint surface to a high gloss finish. Most finishing polishes are formulated with lubricating oils, which enable a longer working time.
19.     Spread a finishing polish using a non-abrasive foam pad at 900-1000rpm and then increase to 1200-1500rpm until it goes clear and then a few passes at 1000rpm.(See also Jewelling )

Notes:
1.        I wear a headlamp when I’m wet-sanding so I can see the work area better.
2.        Maintaining a clean work surface is of paramount importance, so wash the paint surface periodically to remove the accumulated abrasive dust
3.        It is also advisable to carry out a wipe-down process to ensure that there are no polishing oils and/or abrasive dust is not ‘filling any defects, and to determine if the surface is defect free or if further work is required
4.        Aluminium Oxide exhibits a high degree of friability. This means that when heat and pressure are applied it fragments. This is highly desirable because when it creates new sharp edges, this self-renewing property allows aluminium oxide to last longer than most other finish papers.
5.        Finishing paper quality - cheaper paper will induce deeper sanding scratches, which will be more difficult to remove
6.        Wet-sanding can also be done using a random orbital polisher that has a short eccentric offset (typically 5/16 – inch)

Alternative –
a)       Four Star Professional Abrasive Enhancing Gel, extends sandpaper life and  adds lubrication - non-toxic,  use instead of water
b)       3M™ Trizact™ Hookit™ II Clearcoat Sanding Disc - P1500 (PN 02069)- large area wet-sanding, runs damp, long lasting, excellent for texture matching and sanding contours, removes nibs and other defects, leaves a very refined finish
c)        Micro-Mesh Regular finishing papers (silicon carbide grit with standard backing) - The standard grade of Micro-Mesh used for the majority of operations on plastics, paints, wood and most metals and polymers.  It is used to produce a uniformly smooth surface and bring the surface to a high gloss finish.  Available in grades 1500 to 12000 (30 to 2 microns)
d)       Unigrit finishing papers -http://bit.ly/6cW2TP

Bi-directional sanding- if you are sanding in a \\\ pattern with the 2000, then sand in a /// pattern with the 2500, once all your lines are opposite then you know you have completely covered the area. (See also Polishing, Spit Shining, Colour, Depth and Clarity, Legal Stuff, Wet Sanding / Polishing)

3M Nib Pad and Scalloped Disks

3M Finesse-It Hand Sanding Pad.
This 3M product is a small (36.5mm) hand held sanding pad and is used with our 3M micron abrasive discs typically to remove micro imperfections on the repaired dent, or can be used to gain a "read" of the dent by flatting the top of the dent, this usually shows any highs or lows left over.
3M™ Sanding Sponge
Soft foam sponge with sanding abrasive coating on three sides of block form; designed for contour and flat sanding.

Going through the grits

What does this mean?” It’s a very similar idea to ‘Least aggressive first’ it refers to the process of using different grit finishing papers of progressively finer grit or foam / wool pads with progressively denser pads to get a smooth finish (i.e. using finishing papers 500 grit increments will yield flatter results - 1000 > 1500 > 2000 > 2500 > 3000)

By going through the grits each progressive piece of grit finishing paper or pad removes the scratches from that previously used. Always start with the least abrasive combination, i.e. a machine polish and the least aggressive foam / wool pad. If that combination doesn't remove the imperfections, using the same machine polish and change to a more aggressive pad, if the surface imperfections remain, then step-up the abrasive polish and use the least next level (abrasive)only when the paint has a consistently level, smooth, satin finish should you continue to the polishing stage.

Guide Coat

Although this step is not absolutely necessary, I'd recommend guide coat as it provides a visual guide to a smooth surface when sanding most primers; so you know that you got the surface level. It is certainly a good idea if you want to achieve a really good result. Also I wouldn’t recommend doing this with ordinary primer/surfacer as it is usually not thick enough to rub back.

Usually a decent sized pressure pack (SEM Gide Coat Black) aerosol will be sufficient for most cars, the quick drying formula won't clog sandpaper just be sure it is acrylic not enamel as enamel will react with the top coat acrylic if there is even the smallest trace of it on the panel

·         Spray a light coat across your panels. Read the instructions and allow enough drying time before sanding.
·         Use 800-1000 grit finishing paper used wet and with a sanding block. Once again you want to follow the lines of the panel and keep plenty of water on the surface. Without the use of a guide coat these imperfections would have showed up after the top coat was on. Hence the reason to use a guide coat!
The beauty of high-fill primer is that 99 percent of the time you can sand out these imperfections without the need for more filler or reaching the bare surface below. Be extra careful at the edges of the panels as it is easy to sand through the primer there and as with the speed file, don’t be tempted just to sand one little area to get rid of all the guide coat, keep the sanding block moving across a large area until all the guide coat is gone. If you do happen to sand through the primer it is simply a matter of applying some more primer and a guide coat to the area and sanding again.

Once you think you have sanded the entire panel wash it down with clean water and check for any remaining guide coat, re-do any problem areas and finally either dry the panel with compressed air or leave it out in the sun for an hour or two.

An important note regarding primer – 99% of primer/surfacers, spray putties etc. are porous meaning that they will absorb moisture.
The amount of time between applying the primer and the top coat should be as little as possible and once the wet sanding is finished be sure to dry the panel down as much as possible. Any moisture trapped in the primer has the ability to ruin our nice new paint job.

Final polishing

First step is to completely remove all the sand scratch marks. Subsequent polishing steps will involve polishing for maximum gloss and then finessing (jewelling) for maximum clarity. You can't be in a hurry in any polishing step or you risk missing some imperfections. It needs to be flawless.

Using a PC
1500 >2000> 3000 grit 3M Perfect-It Trizact speed 3 -4.Remove sanding scratches with a suitable finishing polish, or use a  4-inch Purple Foamed Wool pad and M105; followed by M105 on an LC Orange foam pad and finally M205 with an LC White foam pad.

Personal Protective Equipment (PPE)
For your safety and the legally required protection of employees, you will need to have personal protective equipment available that will include a respirator fitting for you and your employees. At no time should you endanger yourself or others, take any unnecessary risks or infringe any laws.

Protection from Potential Health Hazards
1.        Warning: Always use ground fault protection interruption (GFPI) when using any electrical device around water
2.        Eye Protection: I would strongly advise the wearing of safety glasses or visor when operating any machine polisher.
3.        Ear Protection; the constant pitch of a polishing machine could affect your hearing so wearing ear plugs would be wise to protect you from hearing loss.
4.        Hand Protection; Gloves- with the verity of chemicals a detailer uses on a daily basis wearing chemical-resistant gloves resist penetration and permeation, and will provide protection against dermatitis and chemical burns. Gloves can provide protection, but they must be chosen with care, the proper selection matched to the hazard is critical. Chemical-resistant gloves resist penetration and permeation, and cam protect against dermatitis, chemical burns and corrosion.
5.        Respiratory Protection (N95): Materials such as aluminium oxide (Aluminium oxide is on EPA's TRI list if it is a fibrous form) or silicon carbide (Nuisance particulate-Accumulation in lungs) used in polishes and compounds, and powdered fillers (Crystalline silica poses a serious inhalation hazard because it can cause silicosis) and Isocyanate clear coat residue represent a hazard to your lungs and may cause respiratory distress. Use  a NIOSH-approved half face respirator equipped with a combination filter cartridge should be worn while using them
6.        Consult the current 3M Respiratory Selection Guide for additional information or call 1-800-243-4630 for 3M technical assistance.
7.        Material Safety Data Sheets:  Use a ring binder or other filing system to ensure the appropriate MSDS is always available to identify hazardous substances
8.        Work Hygienic Practices: Rinse cloves under running water before removing them
9.        Protect yourself, work safe. As in all things, allow common sense to prevail and proceed with due caution

GFCI and Extension Cord
Ground Fault Circuit Interrupter and Extension cord selection is based on two main principles. First, the cable should be able to carry the current load imposed on it without overheating. It should be able to do this in the most extreme conditions of temperature it will encounter during its working life.
Second, it should offer sufficiently sound earthing to (a) limit the voltage to which people are exposed to a safe level and (b) allow the fault current to trip the fuse or MCB in a short time. To meet these requirements requires consideration of the circuit load current (AMPS) a reasonable voltage drop, cable thickness (G) and length (feet) and the over-current protection device

Prime Wire & Cable Duplex GFCI -residual current device is also known as a ground fault circuit interrupter (GFCI) junction Box with 6-Ft. cord, Model# GF200806 Portable GFCI duplex receptacle detects power leaks and shuts off electricity in less than a second to prevent shock. Test and reset buttons Tough jobsite box with 6-ft. 12/3 SJTW power cord UL listed, meets OSHA standards.

Prime Wire & Cable 50-Ft extension 12/3 Neon Power Cord — Blue, Model# NS514830 Bright NEON extension cord stands out for easy identification. 12 Gauge, SJTW, 3 prong cord features super-flexible vinyl jacket with a cold temperature rating of -31°F. LIGHTED connector indicates when power is on. Cord is water and flame resistant and rated at 15 amps, 125V, 1875 watts, UL listed and meets OSHA standards – Northern Tool

Wire Resistance and Voltage Drop Calculator - http://www.stealth316.com/2-wire-resistance.htm

Bibliography

1.        Perfect-It 3000 Training Class
2.        Eastwood Technical Library - Eastwood Company Home Page
3.        Glasurit, Advice on Paint and Paintwork Defects - Glasurit
4.        Colour Sanding and Polishing - Welcome to System One APS
5.        Eastwood Technical Library - Eastwood Company Home Page


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