[: Polishing is the process of creating a smooth and shiny
surface by rubbing it or using a chemical action, leaving a surface with significant
specular reflection and minimal diffuse reflection. When the surface is
magnified thousands of times, it usually looks like mountains and valleys. By
repeated abrasion, those "mountains" are worn down until they are
flat or just small "hills." The process of polishing with abrasives
starts with coarse ones and graduates to fine ones.]
I've spent many
hours meeting and speaking with Engineers, paint chemists, product formulators,
and abrasive manufacturers and polishing pad manufacturers and have gained
insights into paint surface polishing that has afforded me an understanding of
how all these things interact to form a process, on a scientific level paint
polishing is the sum of all these parts.
Polish a paint
surface correctly (regardless of the
machine we are using) the goal is leave
a series of scratching that is so fine that it becomes imperceptible to the
naked eye.
The following ingredients are formulated in a polish;
·
·
Water - the more water there is in a compound, the softer it
will be
·
Solvent - act as a carrier system and to make the other
ingredients soluble. By adjusting the type of solvent, you will determine how
long it takes the product to dry.
·
Abrasives - used to remove surface swirls and marring Abrasives
can be soft or hard; the most common abrasive used is silica however; many
formulators are also using aluminium oxide.
·
Diminishing abrasives - break-down due to friction and then go on to burnish the paint to a
bright shine
·
Non-diminishing abrasives - you polish until the defects are
removed, not until the polish has diminished
·
Surfactants - defined as a material that can greatly reduce the
surface tension of liquids
·
Colouring - is used strictly for customer appeal, traditionally
compounds are tan or olive in colour, so most manufacturers colour their
compounds accordingly.
·
Fragrance - is only for customer appeal
·
Waxes - a small amount is used to produce gloss and fill small
imperfections. And is sometimes used for surface lubrication
Emulsifiers - an oil/water emulsion is used to
stabilize the product and make it easier to useA polish or compound is a specially
formulated emulsion of materials designed to remove paint surface imperfections
such as scratches, oxidation, stains, and acid rain etching. Compounds are
formulated in both liquid and paste form, and generally contain more aggressive
abrasives than are found in polishes. The compound step is usually followed a
polish and then a polymer sealant, or a glaze, or and/or a Carnauba wax.
Whether liquids or
a paste, an apt description of a compound (800 -1500 grit); is ‘liquid
sandpaper’ they are formulated from a few basic components: water, oil, and
solvent, diminishing abrasives, surfactants, colouring and fragrance. Placing a
small amount between your finger tips will no longer give an indication of
compounds abrasiveness; this is due to the particles being emulsified in oil
and not released until subjected to friction
The main ingredient
in a polish or compound is the abrasive; wither diminishing or non-diminishing,
the type of abrasive, their size, hardness and shape. The abrasive ability of a
polish / compound is also affected by the type of lubrication (polymer, mineral
oil, etc) used Some very abrasive compound polishes don’t feel abrasive to the
touch because the particles are formulated in a water-in-oil emulsion for the
cooling-lubricating process and are not released without friction or pressure /
time.
These factors will
determine what that polish will ultimately do to the paint surface, the larger
the abrasive, the more aggressive it will be on the paint surface. The most
common abrasive used is silica, which is much, much harder than aluminium
oxide; however, many formulators are also using aluminium oxide.
Most good quality
compounds and polishes contain abrasives and are either silica or aluminium oxide, or a combination
of both. Think of them as liquid sandpaper, buffered or cushioned in
lubricating oils that are formulated with solvents, water and 0.3 –0.4µ
(micron) abrasive particles, in an
emulsion that enables both cooling and surface lubrication, that spreads and
tumbles the abrasives that diminishes with friction, or breakdown with
pressure.
The paint film
surface also requires occasional polishing to maintain a pristine paint film
surface and to ensure that any accumulated microscopic contamination in the
paint surface crevices does not cause paint staining and that this dirt is not
sealed into the paint by the application of wax or sealant.
The use of abrasive
type polish / cleaners should always be restricted to specific problems. Most
original paint finishes are tougher on the outer surface than the layers
underneath. The outer layer (which contains the paints UVR protection) should
be preserved as far as possible.
Water
The more water
there is in a compound, the softer it will be. That is the difference between a
liquid and a paste compound. Neither is better than the other in terms of
performance. It really comes down to what the detailer prefers.
Solvents
There are basically
three solvents that can be used: mineral
spirits; kerosene; and naphtha. Mineral spirits is usually a quick-drying
solvent that will make the compound dry quickly, speeding up the job. However,
it will also increase the possibility of burning the paint if used incorrectly.
Kerosene, on the other hand, is a slower-drying solvent that reduces the
tendency to burn paint. It will, however, increase the work time with the
compound.
What happens when
the solvents vaporise? Polish and many
surface protection products are formulated with oils to enhance the surface or
to nourish leather surfaces, neither of which is necessary
The purpose of oils
is to provide lubrication, the amount used will determine the working time of
the compound. Oils provide surface lubrication to help it spread; it is made
into an emulsion with solvents that make the product into a pliable liquid. The
emulsion of oil and its catalyst, a solvent, only require air to outgas as the
oil/solvent solution will vaporise, sometimes a very thin film of oil is left
on the surface, which is usually removed when the surface is wiped with
isopropyl alcohol (IPA) this is important if the following product is a polymer
as it won’t bond as an oil film acts as a buffer to the cross-linking process.
Oil-in-Water
Emulsion
[ : a dispersion of small globules of one liquid in a
second liquid with which the first will not mix, i.e. an emulsion of oil in
water]
Synthetic polymers manufacturers are getting away from using petroleum
distillate based silicones and are now using Polydimethylsiloxane silicones to
produce a mild oil-in-water emulsion. Being primarily water based these are
safe for all types of pant and are biodegradable.
Chemists also use these water-in-oil emulsions to reduce emulsion
particle size, to stabilize the emulsions, and to improve spreading and
coverage of the polymers products. Emulsion polymerisation takes place in an
emulsion typically incorporating water, monomer, and a surfactant. The most
common type of emulsion is an oil-in-water emulsion, in which droplets of
monomer (the oil) are emulsified (with surfactants) in a continuous phase of
water.
If the polymerisation is carried out in the absence of surfactants, it is
generally known as a suspension polymerisation. The advantages of emulsion
polymerisation include: more complete surface coverage to prevent contact
between unprotected areas, viscosity remains close to that of water and is not
dependent on Covalent (molecular) weight and the final product can be used as
is and does not generally need to be altered or processed.
Emulsions
Emulsifiers and
emulsions can seem like mysterious concepts but actually are very common. Milk
is an emulsion of milk fats and solids held in suspension by an emulsifier
called casein. Oils and polymers are often suspended in an emulsion and used as
a carrier system in waxes and polymer sealants.
Oil will not
spontaneously mix with water, but the presence of a surfactant provides a
decrease in surface tension that allows the formation of small droplets of oil
in the bulk of water (or vice versa)Compounds, polishes, waxes and sealants are
most commonly comprised of very tiny droplets (emulsion) of solvents, abrasives
and active ingredients held in suspension in a water solution by emulsifiers
Surface Filling /
Masking Abilities
Every polish that
uses oils or polymers for lubrication will
fill surface marks that are not removed and mask defects. If you don’t
remove the lubricating oils (Anhydrous Isopropyl (99%) Alcohol (AIPA) wipe-down
then you are by passing the post polish inspection and the oils left behind
will mask the defects.
Note – some polishes contain specific products (i.e. Kaolin
(China clay) or Diatomaceous earth) to mask surface marks, this type of filler
will also be removed by the IPA wipe-down process.
Polishing
Abrasives are made
from chromium oxide, aluminium silicate, zirconium silicate and carbides; their
abrasive ability depends on the shape of its particles, not necessarily its
size. A medium size, spiked abrasive will tumble and dig. However, a large
round crystal won't leave a deep scratch.
A large hard
abrasive may also be brittle. It will cut once and lose its edge, while a
softer small abrasive will hold its edge and keep on cutting. Many smaller
abrasives have wedge shaped edges protruding from triangular crystals. These
can easily slice through an oxidized layer of paint
Polishes are a very essential product
for the overall appearance and condition of the paint finish. There are
abrasive polishes formulated to remove paint finish issues such as oxidation or
other paint surface imperfections such as surface scratches. Light polishes
contain either mild abrasives and / or a chemical cleaner (solvent) most mild
abrasive polishes will remove medium scratches or surface imperfections,
whereas a strong abrasive compound polish
rely both on a chemical cleaner (solvent) l and mechanical abrasives to
rectify more serious paintwork issues.
Proper washing and
drying techniques are the best way to avoid the need for polishing. Using a
chemical paint cleanser versus polishing on a clean finish to simply remove old
wax/sealant is another. And always follow the rule of using the least abrasive
polish and pad combination (working smarter not harder)
Polish and Wax are
very different and should not be confused, although the retail industry has
blurred them together in marketing.
This is not
generally possible because the substances perform separate functions; in
general terms a wax is used for protection and a polish is abrasive and used
for surface correction. The word ‘polish’ is used because when you apply wax to
a vehicle you are ‘polishing the car’
[Detailers]
A polish is an abrasive product that
removes imperfections and levels a surface to enable the light to reflect
evenly.
[General
public] The word shine is
also used in the context "I polished with a wax to make it shine" hence the confusion between the two.
Paint Polishes and
Protective Coatings
·
Compound
– an aggressive grade of polish used to remove deeper scratches
and for paint renovation
·
Polish – an
abrasive compound that removes surface scratches and impurities, it provides
shine and prepares it for a wax or sealant protection.
·
Paint
Cleaner (pre-wax cleaner) – a chemical cleaner that contains mild
abrasives (i.e. Kaolin (China clay) or Diatomaceous earth ) that is used to
clean a paint surface but they will remove wax residues, embedded dirt and light stains from your paint , but they will not remove ingrained surface scratches. Use
paint cleaner after detailing clay and before waxing.
·
All in
One) – very
similar formulation to a paint cleaner, the main difference is that an AIO type
product provides limited surface protection
·
Glaze – used
by detailers for show car to obtain maximum light reflection. They produce a
“wet" look to the surface with oils to maximize surface gloss and may
contain fillers (Kaolin or China clay) to hide minor defects not removed by
polishing or for use when the paint is thin and you don't want to remove any
more, even if it is microns. A glaze is a very fine (usually) non-abrasive
polish. Some glazes are safe to use on fresh paint, as they allow fresh paint
to outgas. They will provide little if any surface protection.
·
Wax – an
organic or synthetic protective coating that is applied to the exterior surface
of an automobile to improve shine and prevent oxidation
·
Sealant – a
polymer sealant comprises an open linked molecule, which forms a bond with the
paint, this is the main reason for their durability; these open linked polymer
molecules join together to create an elongated mesh like effect that reflects
light efficiently due to their inherent flat surface. Because they are usually
very transparent they transmit the surface colour faithfully, but they have
very little depth resulting in what is perceived as a very bright, flat silver
glow
·
Quick
Detailer - Detailers spray (QD) have many uses; to aid in final drying to
remove water spots, used with Zaino (Z6) to help ‘smooth-out’ finish between
coats of sealants, it also removes smearing from the overuse of product. Use a
1:1 solution of a detailing spray and distilled water as it makes them easier
to apply and more economical. To remove heavy dust use Optimum No Rinse (ONR) a
waterless wash as it will provide a lubricant that a detail spray doesn’t.
Waxing or applying
a polymer sealant to a surface that has not been properly cleaned will only
result in a shiny layer over dull, dirty paint - not the deep smooth, optically
perfect crystalline shine that is obtainable.
Abrasives
The ability for a
polish to "cut" depends on the shape of its crystals or particles,
not necessarily its size. A medium size, spiked abrasive will tumble and dig.
However, a large round crystal won't leave a deep scratch.
Aluminium oxide has
a hardness factor MOHS 9 and will not break down during polishing. Rather the
larger clusters of aluminium oxide reduce in size.
A large hard abrasive
may also be brittle. It will cut once and lose its edge, while a softer small
abrasive will hold its edge and keep on cutting. Many smaller abrasives have
wedge shaped edges protruding from triangular crystals. These can easily slice
through an oxidized layer of paint
Types (Grades) of
Polishes
A surface scratch
that will `catch' your fingernail is approximately 0.04 Mil (1.0 µ Microns)
deep will usually require wet sanding and refinishing. Other than that >
1000 grit scratches can be removed with a polish/compound and a machine
polisher.
The ability for a polish to
"cut" depends on the shape of its crystals or particles, not
necessarily its size. A medium size, spiked abrasive will tumble and dig.
However, a large round crystal won't leave a deep scratch.
A large hard abrasive may also be
brittle. It will cut once and lose its edge, while a softer small abrasive will
hold its edge and keep on cutting. Many smaller abrasives have wedge shaped
edges protruding from triangular crystals. These can easily slice through an
oxidized layer of metal.
Liquid polishes tend to perform
better than pastes because they allow you to use the oxidation you're removing
as an abrasive. The oxidation will be no coarser than the abrasive in the
polish, and since aluminium oxide is second only to a diamond abrasive, it
makes an ideal cutting compound.
1.
Compounds
- are the most aggressive,
most abrasive type of polish and will remove the largest amount of clear coat
in the shortest period of time. Compounds are commonly used on severely
neglected vehicles and to clean up wet sanding marks. Compounds will almost
always leave behind some marring, hazing, or holograms and should always be
followed up with a finer polish or multiple polishes.
2.
Abrasive
Polishes – the most polishes that correct moderate paint imperfections fall
into the category of an abrasive polish. They are a step below compounds in
terms of aggressiveness and usually do not finish down as well as a finishing
polish. On most paints, it is recommended to follow up an abrasive polish with
a finishing polish to remove any micro-marring, hazing or holograms as well as
increase the depth and gloss. Some abrasive polishes are capable of finishing
on certain paint.
Diminishing Polishes - will remove very minor imperfections in the paint, such as
micro-marring, hazing and holograms. A finishing polish is formulated with a
very mild abrasive that finely polishes the paint surface and effectively
enhances light refraction and reflectivity. They are also used to burnish
(jewelling) the paint to achieve an exceptional level of gloss and depth.
4.
Paint
Cleaners - are designed to enhance the depth and gloss while properly
preparing the paint for a sealant or wax. Sometimes paint cleaners can have
micro abrasives or they can be non-abrasive. They typically will not remove
imperfections that require levelling the clear coat, but can remove some
oxidation and mineral deposits.
Always choose the least intrusive product, it is preferable to
polish 2-3 times to restore the paint film surface than to use an unnecessarily
abrasive machine polish / foam pad combination. Before commencing polishing do
a test panel on the car, once you have achieved the desired results with the
chosen polish / pad combination proceed
Difference between
Diminishing and Standard Abrasive Polishes
Diminishing Abrasives Technology
A non-linear
abrasive that require kinetic (or dynamic) friction - while the majority of
polishes on the market use a form of diminishing (non- linear) abrasive, which
you polish to a ‘haze’ (when a polish "flashes" from a liquid paste
to a light semi-dry haze, much like a coating of Vaseline®) the diminishing
polish has then broken down and is ready for removal. Diminishing abrasives, as
the name suggests; t he abrasives become smaller with friction, and therefore
go from removing paint defects to polishing the paint, which produces the
shine.
If you don't break
them down sufficiently, you are just grinding those abrasive particles into
your paint, without polishing it, which can leave behind marring and other
paint surface imperfections. So it’s important to know when a polish has broken
down because if you take it too far you will re-introduce surface marring.
During the polishing process, trace amounts of paint and / or oxidation is
removed; this can cause the debris and the polish to “clump” together. This can
cause a haze to the paint surface, a wipe-down or a paint cleaning product will
eliminate this.
Pros - Menzerna diminishing abrasive polishes are formulated with a
long lasting lubricant. The abrasives break down before the lubricating oils
dry out, thereby giving polish a longer working time and producing less
abrasive dust and avoiding dry buffing.
Cons - Menzerna lubrication oils can be really resistant to removal;
it may take 2-3 IPA wipe-downs.
Non- Diminishing Abrasives Technology
A linear abrasive
that require time and pressure - unlike diminishing abrasives, which require
kinetic (or dynamic) friction to enable the abrasives to 'break-down to obtain
the best possible finish (and avoid holograms) non-diminishing abrasives react
very differently. It will be as abrasive as you want it to be, time and
pressure applied (linear abrasive) being its working criteria.
Linear abrasive
polishes / compounds provides a constant cutting abrasive, as the
abrasives remains uniform in size
throughout the polishing process, so you need to check the surface often. They
should be used with a cutting foam or wool pad until the defects are removed
(1200 – 1500 RPM) but do not allow the polish too completely dry (as this will
also produce holograms) and ensure that pad surface is cleaned by removing
paint / polish debris regularly This type of compound / polish process usually
requires subsequent polishing step(s) to further refine the finish and to
produce a shine
Cons - the lubricating oils dry out, thereby providing a shorter
working time, producing more abrasive dust and the possibility of dry buffing
Amount of Polish
Place a small
amount (approx 3 x 1/16th-inch diameter or a 1 ½ x 1 ½ -inch X) of polish onto
the centre of a clean primed pad. Approximately 1.5 – 2 oz for a mid-sized
vehicle
Polish / Compound
Application
If you were to
apply polish to a body panel, and then place a pad on the surface and turn the
machine on, it would be very difficult to control and will produce hazing. This
is due to most of the pad being "dry". Polishes and compounds appear
to work better when the foam pad is ‘primed’ some things to note about pad
priming: the cutting ability is increased, a better finish is obtained, it
reduces any product ‘flashing’ problems, it produces a more even finish and the
polishing machine is less likely to hop.
Use a very slightly
distilled water dampened pad, not too wet (otherwise the polish will clump);
then spread the polish / compound over the pad evenly and ensure it is absorbed
into the foam, apply some pressure to the surface and scrape any excess product
from the pad
Apply the compound
or polish to the surface and spread the polish using the foam pad with the
(Orbital Polisher) machine off. This coats the pad and the surface being
polished with product to prevent scratching or hazing the finish, then place
the foam pad flat on the surface and turn the machine on. Do not, under any
circumstances, turn the polisher on with any portion of the foam pad dry as
this will produce hazing.
Most polishes are
formulated by emulsifying a powdered abrasive in a carrier system (oil /
solvent) the right amount of pressure / friction heat is vital to allow the
polish / compound abrasives to level the paint surface and remove surface
scratches / marring
Dry buffing
Dry buffing
(polishing) refers to when the polishes lubricants run out; non-diminishing
abrasives will start to emits a white dust, diminishing abrasives start to
become translucent (similar to Vaseline on a paint surface). Once you polish
much beyond these points is when friction from dry-buffing can lead to you
creating fine scratches and dullness or even burning the paint.
Polish Methodology (polishes
and pad selection)
Diagnosis is the
key; not guesswork; examine the vehicles bodywork, a ‘bag-test will ascertain the
need for detailer’s clay, and a 3M Sun Gun or a Brinkman light will help you
find any evidence of surface blemishes i.e. swirl marks and scratches.
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. The paintwork should be evaluated with a paint
thickness gauge to see what thickness of clear coat remains before you decide
how much paint renovation can be safely carried or wither paint preservation
would be the appropriate option, before you proceed, measuring with a paint
thickness gauge will dictate the choice and abrasiveness of polish / compound
for correction or renovation level required or indeed possible
Always follow the
rule of starting with the least abrasive combination, i.e. a machine polish and
the least aggressive foam or wool pad (working smarter not harder) 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 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
When removing defects
from the paint surface, consider not only which polish / compound you'll be
using, but how you'll be using it. You choice of machine speed, pad
construction, pad size and applied pressure will all impact the abrasive
abilities of the polishing liquid.
Decide on a one,
two or three step polishing routine and select a suitable pad. After testing a
section to confirm this method, 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 process that will produce the best
possible finish, once this is established repeat the process over the entire
paint surface.
Select a
‘typical’ area - (one that represents the type of defects that you want to remove)
and starting with the least abrasive polish and / pad combination and then
proceed until the defects are removed. This is the polish / pad combination
you’ll need to use
Relevant
Articles
1.
3.
“Polishing
machine backing plates” -http://www.autopia.org/forum/autopia-detailing-wiki/144681-backing-plates.html
4.
“Strikethrough
“-http://www.autopia.org/forum/autopia-detailing-wiki/142220-clear-coat-strikethrough-breakthrough.html
