Sunday, 23 July 2017

Surface preparation prior to polishing

Process over Product
A wax or sealant can only reflect what is underneath it, so a clean, level well-prepared surface is the most important consideration (85% of a surfaces reflectivity is its preparation) along with applied product clarity. If you apply a product over a surface that is dirty or one that has surface imperfections a wax or sealant will not disguise it, only highlight them.

Surface preparation is one of the most important steps when polishing to achieve a flawless finish

Always use the least abrasive product/foam pad combination before ‘stepping-up’ to something more aggressive. The most important first step in the process of paint surface detailing is diagnosing the paint surface; density of clear coat (hard or soft) or single stage paint, surface condition; ascertain the severity of the surface blemishes with an inspection light and the paint thickness available, measuring with a paint thickness gauge (PTG) will dictate the choice and abrasiveness of polish / compound for correction or renovation level required or indeed possible.

Assess the correction level working through the range of polishes from the lightest abrasive upwards until the desired level of correction is reached. Selecting the correct pad/polish combination for the vehicles paint/defects can take just as long as the paint correction process

Before polishing a painted surface ensure the surface is free from both surface and sub-surface contaminants. This is vital; if your car is covered with metallic brake particles you will introduce new scratches in the surface whilst polishing it. If the paint surface is heavily contaminated (Industrial fall-out, Metallic Brake dust, Rust Blooms or Oxidation) it may require a decontamination process (See Paint Decontamination article)

Always remove surface contaminants before you polish

One of the easiest methods of ensuring that your surface is contaminant free is the so-called ‘Bag Test’. After washing and drying your vehicle place a plastic sandwich bag over your hand or fingers, gently pass over the surface. Does the surface feel silky smooth or rough and gritty? If you felt roughness and/or grit, your surface is contaminated.

Use a Nanoskin surface prep towel (HD Nano Prep) and then a Chemical paint cleaner (Klasse AIO) and/or a Bituminous Asphalt remover (Stoners Tarminator) to remove above surface contaminants. Then proceed to remove sub-surface contaminants with decontamination product (IronX or ValuGuard) to ensure all contaminants have been removed repeat the ‘Bag Test’.

Surface contaminants
Superficially-adhered surface contaminants as the name imply sit just above the surface of the paint. These contaminants become embedded in the clear coat when the paint is subjected to heat radiation; they comprise; paint residue (oxidation) tree sap and resin, bituminous asphalt (road tar) particles of road dirt (grit) and grime, carbon emissions from catalytic converters, bird excrement, calcium, tar, oil, hard water deposits, calcium or any pollutant type substance that adheres to your paint surface, sometimes invisible the naked eye. This contamination creates a film on the paint surface, making it difficult for a paint protection product to form a proper bond and negatively affects its durability

Then why not simply use a surface prep towel or detailers clay  to remove surface contaminants; the  answer is that a surface prep towel can be used to remove surface contaminant, but a potential problem arises in that organic contaminants (tree resin and sap,  honeydew and insect exoskeletons an), which generally comprise much larger particulates than inorganic contaminants (rail and brake dust, bitumen (tar), etc)  and therefore have greater potential to cause surface marring between the surface prep towel and the paint as the towel is moved across the paint surface.

Given that some contaminant residue (acid rain, industrial fallout, sintered brake or rail dust) are usually highly acidic and/or will permeate a painted surface, it makes far more sense to remove them chemically and neutralize the paint surface rather than by using an abrasive polish, as dissolving them using a paint decontamination system and then rinsing them away virtually eliminates the risk of causing surface scratches

Compounding, Polishing, and Finishing are all different polishing methods that do not necessarily have to be applied consecutively. The appropriate combination of polishing steps depends on colour and quality of the coating as well as on the required quality of the surface.

Never mix polishes on a foam/wool pad and never use a pad that been used for compounding for polishing unless it’s been washed as there may be compound polish residue that will be too aggressive for polishing

Prior to the polishing process; you’ll need to remove the old paint protection and any oxidation first so you can get down to the bare paint where these contaminants have attached themselves, the paint should already be washed and clayed for maximum results, then using a chemical paint surface cleaner as any dirt and or oxidation on the paint can interfere with the polish.

The paint surface should be as clean as possible, this will ensure that nothing comes between the polishing pad and the surface to interfere with the abrasives and the pads will not get clogged with surface debris. After polishing a wipe down 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 polish residues (oils, wax, silicone, etc) to settle in the swirls, hiding the true paint finish.

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 painted surface if there are any oils or moisture present and it will affect durability.
b) Silicone will cause surface smearing and will also affect durability

Paint Surface Cleaning
Vehicle manufacturer studies have shown that failure to remove environmental contaminants, like embedded rail dust, acid rain, industrial fallout and other environmental contaminants from a paint film can cause premature degradation of the paint system.

There are three distinct type of paint cleaner; Abrasive, Chemical (solvent) and Chemical (acid)

a) Abrasive - Detailer’s clay Automotive clay is not a replacement for polish or a compound; it is a pliable, petroleum resin product, containing a mild abrasive(s) i.e. kaolin, silica sand, calcium carbonate, alumina, ceramics quartz and also silicon carbide that polishes and exfoliates bonded surface contaminants.

Detailer’s clay will remove most but not all of the iron particulate that is the cause of the rust "blooming", too for a corrosion decontamination system to be effective requires the complete removal of all particulates and the corrosive acids they generate that have penetrated the paint surface system.

These abrasives are extremely small with an average particle size of 1- ยต (micron) dependent on the aggressiveness required, mixed in with a powdered synthetic detergent. The abrasives 'shear' the surface contaminants, the sheared particles are then encapsulated by the clay (i.e. the top of the metallic particle leaving the rest embedded in the paint, which acts as a conduit for moisture to the various paint layers, allowing it to continue generating corrosion damage) While clay products are useful for overspray and cleaning surface contaminants, it cannot permeate and deep clean the pores of the paint.  (See also Decontamination and acid Neutralization)

Zaino Z-PC Fusion Dual Action Paint Cleaner - a water-based formula with  tri-particulate, diminishing abrasive system (no fillers or oils) which allows you to use the oxidation you're removing as an abrasive that removes minor scratches, swirls, oxidation, wax build-up and other surface blemishes

b) Chemical (solvent) - formulated with solvents and/or very fine abrasives (Kaolin or China Clay) Most of their cleaning ability is provided by the cleaning solvents, not the polish. Used to remove old wax, embedded dirt and light stains from paint; they help to restore gloss and remove light surface imperfection (oxidation, paint stains, marks left from bird excrement, water ‘spots’, and etc). They are designed to be used as often as required without measurably reducing paint thickness. Some paintwork cleaner’s act as 'All in One' products, so not only do they clean and polish but also provide limited protection

P21S Paintwork Cleanse, a gloss-enhancing chemical cleanser that contains fillers (Kaolin or China clay) will remove old wax, light swirls and oxidation. It can be applied by hand or with an orbital polisher. Paint cleaners are designed to remove old wax, oxidation, embedded dirt and light stains from your paint surface. They can remove micro-marring of the surface (i.e. light towel marks) but typically will not remove imperfections that require leveling the clear coat but can remove some oxidation and mineral deposits.

Swissvax Cleaner Fluid Professional Finish - its cut and gloss characteristics make it ideal for removing wash marring and faint swirl marks on all paint types, and its filler-free formula also makes it a great choice for refining out machine holograms after heavy compounding. Add to the equation the fact that it's easy to use, generates no dust and laughs in the face of sticky paint, and it's easy to see why it is a must-have product for minor enhancement duties on all modern Porsches and Range Rovers.

Swissvax Cleaner Fluid Regular - advanced chemical cleaning agents strip away any residual grime and old protective layers, while kaolin clay particles and heavy glazing oils visually reduce the extent of wash marring and minor swirl marks by filling such defects and robbing sunlight of sharp edges off of which to reflect. In short, Swissvax Cleaner Fluid Regular is a great product that effortlessly cleans and transforms the appearance of well-maintained paint in no time at all, which makes it ideal for enthusiasts and professionals alike.

Chemical solvents paint cleaners are good to use if you want to prep the paint surface prior to applying a wax (without polishing). My preference would be to use an IPA or DuPont’s PrepSol as they don’t leave any (silicone/mineral) oils or etc behind, as these can cause problems when polishing if they are not removed

Swissvax Regular Cleaner Fluid - an advanced paint preserving solution containing heavy polishing oils that will refresh the paintwork and does not contain abrasives. Cleaner Fluid has to be applied before the first Wax application and easily removes swirl marks, light scratches, tar spots and tree sap as well as old wax and other residues and provides a smooth and perfect surface as an essential basis for the wax application.

c) Chemical (acid) - decontamination and acid neutralization system, ValuGard is the most recognized and one of the few OEM approved chemical neutralization system in the industry.
While clay and chemical cleaners are useful for cleaning the paint surface they cannot deep clean the pores of the paint, or neutralize rust spots. This can be accomplished with a chemical cleaning acid and neutralization system.

Schedule: every three or four months (dependent upon environmental conditions and vehicle exposure) more often on light colour paint. To optimize the reflective properties and appearance of the paint surface, it is best to regularly remove both embedded and surface contaminants and dirt.

Test Panel Area
Diagnosis is the key; not guesswork; as differing density (hardness) of paints react differently to correction, so before beginning to polish measure the paint thickness (PTG) panel by panel to ensure that you do not select an aggressive polish that will remove too much clear coat

The key to the polishing process is to know how the paint will react with each pad/polish combination you consider using. You must know your product and what its capabilities are before using it. This is why a ‘test’ spot is so important.  

The factors that affect the outcome -speed, friction (kinetic energy) applied pressure, foam pad actual surface contact area, pad grit number (abrasive ability) amount of surface lubrication available, the surface area and heat conductivity of material

Select a ‘typical’ panel; one that represents the type of defects that you want to remove and the finish level required. Select an area of 18 x 18-inches and tape it off with painter’s tape, as this is an optimal working section to perform a product test spot; this will help establish a polish – pad combination that will produce the best possible finish that corresponds to your detailing goals for the vehicle. Pay attention to how the paint is responding to your inputs. Stop and evaluate your progress, once this is established; repeat the process over the entire paint surface, adjusting abrasiveness for any low paint thickness.

There may be some areas that have deeper scratches, which will necessitate a more abrasive polish. This is known a ‘spot-correction’. Once this area(s) are completed revert to the original polish/pad combination, there is no need to remove any more clear coat than is necessary 

IPA Wipe down
Courtesy of Dr. David Ghodoussi, Optimum Polymer Technologies

There is a lot of confusing information about solvents in general and IPA in particular. Let's limit our scope to cross-linked (enamel) clear coat finishes since that is the paint system on the majority of the cars we are talking about. Although there are many different paint systems being used, in all cases with this type of paint, IPA or other solvents will penetrate the paint and cause some swelling. Depending on the solvent, the degree of swelling varies and in some cases like with methylene chloride (within seconds) and MEK (within minutes), it can swell it to the point of delamination. IPA and mineral spirits do swell the paint but not to the same level of course.

As the paint swells and expands, it also becomes softer. Since there are many different types of paints being used, some paints might soften to the point that even a gentle wipe down might cause micro marring while others may not mar even at much higher solvent concentrations. That might explain the variations in some of the observations different people have reported.

While fast solvents such as IPA may fully evaporate at higher temperatures (e.g. 90 F) within hours, slower solvents like MS may take several days before they reach levels below 1%. But the notion that the solvents may be trapped in the paint forever or that the paint will soften permanently is absurd since clear coat paints start off with anywhere from 20-70% solvents and if this theory had any validity, then all paints should stay soft and/or some of the solvents should be trapped within the paint forever.

After this brief introduction, let me respond to your specific questions:

1) Is IPA safe for paint and in what dilution?
I would follow the recommendations of 10-25% IPA in water as a safe cleaning solution. The reason for this wide range is due to the variations in the clear coat paint systems. Therefore, when dealing with a soft clear coat or for those who notice a great deal of softening the effect, they should stay at the lower end of the range while others can use the upper limit. Of course, the greater the percentage of IPA, the faster it will remove the oils.

2) Does it soften the paint either temporarily or permanently?
While straight IPA or even 70% IPA can soften the paint excessively, as you increase the water level, the softening effect drops exponentially. In any case, as I explained earlier the softening effect is temporary.

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