Polish / Compound abasive abilities
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Polish / Compound Abrasive Abilities
* Always use the least aggressive product first, evaluate the surface, then only if necessary `step-up' to a more abrasive product and / or pad.
Compounds
A specially formulated emulsion of materials designed to remove paint surface imperfections such as scratches, oxidation, stains, and acid rain etching. Rubbing compounds are formulated in both liquid and paste form, and generally contain more aggressive abrasives than are found in polishes. The rubbing compound step is usually followed by glazing and/or waxing. 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 heated by friction
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.
Oils
Often in an oil/water emulsion; the most common oil used in compounds are mineral oil. The purpose of oils is to provide lubrication, the amount used will determine the working time of the compound.
Abrasives
A hard material, such as aluminum oxide or silicon carbide, that is powdered and carefully graded according to particle size, and used to shape or polish surfaces. these are the most important ingredients used in compounds because the abrasives determine the cutting ability of the product. Abrasives used in compounds come in many grit sizes, ranging from 800 -1500 grit. Abrasives can be soft or hard; the most common abrasive used is silica however; many formulators are also using aluminum oxide. Most good compounds are a combination of both silica and aluminium oxide.
Surfactants
Defined as a material that can greatly reduce the surface tension of liquids
Coloring
Is used strictly for customer appeal, traditionally compounds are tan or olive in color, so most manufacturers color their compounds accordingly.
Fragrance
Is only for customer appeal.
Fillers
Some polishes on the market ( and I emphasize some; but not all polishes) contain a small quantity of fillers, which help to mask imperfections, leaving what appears to be a defect-free surface prior to the application of a wax or sealant protection. The downside of this is that once these fillers are eroded, some of the remaining defects will reappear.
Polish
A specially formulated blend of components designed to remove minor paint surface imperfections, such as fine scratches, light oxidation, water spots, and swirl marks left by the use of rubbing compounds. Polishes may or may not contain waxes or silicones. Water-based polishes are actually an oil-in-water emulsion that is formulated with silicone or mineral oils that act as a lubricant. They remove surface imperfections and impurities; and are available with various levels of diminishing (by friction heat) abrasives of approx 0.3 Micron or less A polish is designed to remove scratches from the paint surface and create a high shine, while swirl remover is product designed to remove buffer swirls, smooth the paint and create a high shine. Although some companies market two products, a polish and a swirl mark remover (SMR) they are both scratch removers and with the right polish / foam pad combination you only need one polish.
The following ingredients are formulated in a polish;
Water
The more water there is in a compound, the softer it will be
====Solvents====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 aluminum oxide.
Diminishing abrasives
Break-down due to friction / heat and then go on to burnish the paint to a bright shine
Surfactants
Defined as a material that can greatly reduce the surface tension of liquids
Coloring
Is used strictly for customer appeal, traditionally compounds are tan or olive in color, so most manufacturers color their compounds accordingly.
Fragrance
Is only for customer appeal
Waxes
A small amount is used to produce gloss and fill small imperfections.
Emulsifiers
An oil/water emulsion is used to stabilize the product and make it easier to use.
Silicone oils
Provide the necessary lubrication for spread ability, replace any lost oils from the (paint) binder system to prevent the system from drying out and they also contribute to the depth of shine and affect the paint film surfaces optics by improving its light reflectance. Oils can be used to make the product easier to work with and leaves a gloss.
The abrasion or cutting ability of a polish on a 0-10 scale; least abrasive to most, a rating of 0 would constitute a functionally nonabrasive material (i.e. diatomaceous earth or Kaolin) a 10 rating would be 800 grit abrasive. The most common abrasive used is silica however; many formulators are also using aluminum oxide(9 on the Mohs scale of mineral hardness). Most good compounds and polishes contain diminishing abrasives and are a combination of both silica and aluminum oxide. Think of them as liquid sandpaper, they are formulated with a lubricant (polymer or solvents in a water-emulsion) and an abrasive size of approx. 0.3 –0.4 micron, (diminishing abrasives) are minerals that diminishes with friction heat, buffered or cushioned in a lubricating oil film, usually in a semi-liquid paste.
Most good quality compounds are a combination of both silica and aluminum oxide. Some very abrasive compound polishes don’t feel abrasive to the touch because the particles are formulated in a water-in-oil emulsion and are not released without friction-heat.
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. Bear in mind that a clear coat has a thickness of 1.5 – 2.0 Mils, removing more that 0.3 mil of clear coat will cause premature paint film failure.
As a point of reference two sheets of Saran wrap placed on top of each other measure 1.5Mil a surface scratch that will `catch' your fingernail is approximately 0.04 Mils deep will usually require wet sanding and refinishing. But there comes a point when you must judge wither removing a scratch will compromise the clear cot and if so you’ll have to ‘live’ with the imperfection (these can be aesthetically masked by using a Glaze)
Compound Polishing Surface Temperature
The temperature of a paint surface should be monitored when using a high-speed polisher, friction heat can cause a rapid temperature rise in the order of 20oF (i.e. initial surface temp 80oF, heat attained with a cutting foam pad at 1,100 RPM for approx. ten seconds is approx. 104oF) the localized paint temperature should be limited to 110 oF. In accordance with the Society of Automotive Engineers (SAE) a temperature of 115 oF will cause the urethane clear coat to soften and the foam pad will cause scratching that is forced deep into the clear coat.
Polish I (compound)
(800 -1000 grit Heavy) levels and removes heavy defects; compound polish removes severe paint flaws and wet sanding marks with suspended abrasives in a mix of oils/solvents/water, which also provides the pad with a lubricant to work it across the paint surface. This will leave behind surface marring or haze. CAS = 8/10
Polish II
(1200 grit Heavy - Medium) levels moderate to heavy defects; polish is again a mixture of abrasives and oils/solvents/water which also provides the pad with a lubricant to work it across the paint surface. This will remove the surface marring, hazed or swirls in the paint surface and restore full depth of shine and surface clarity. CAS = 7/10
Polish III
(1500 grit Medium) levels light to moderate defects CAS = 6/10
Polish IV
(2000 grit Light) levels light defects and removes hazing CAS = 5/10
Polish V
(3000 grit Fine - Finish) has very minor corrective ability and burnishes paint to high gloss CAS = 3/10
Glaze
Very sleight abrasive (Kaolin) usually with oils and wax to fill and add warmth/depth CAS = 2/10
Scratch / Grit Abrasive Comparison
KEY
1.Surface Imperfection
2.Grit Abrasives Equivalent
3.Polish Type
4.Pad Selection Use - Color
1. Very Fine Scratch
2. 2000 Grit Abrasive<
3. Fine Polish
4. Polish / Waxing Pad - White
1. Light Oxidation
2. >2000 Grit Abrasive
3. Machine Polish 1 or 2
4. Polish / Waxing Pad - White or Light Cutting Pad - Orange
1. Medium Scratches / Medium Oxidation / Water Spots
2. 1500 Grit Abrasive
3. Machine Polish 2
4.Polishing / Light Cutting Pad - Orange
1.Deep Scratches / Heavy Oxidation / Orange Peel / Acid Rain Etching
2. 1200 Grit Abrasive
3. Machine Polish 3 or Compound
4. Polish / Cutting Pad - Yellow
1. Deep Scratches / Heavy Oxidation / Acid Rain Damage
2. >1000 Grit Abrasive
3. Heavy Cut Compound
4. Leveling Pad - Wool
1. The abrasive ability is approximately distributed, 60% abrasive ability of the product (grit number) 30% foam composition and 10% pressure applied and/or speed of rotation or oscillation.
2. Increase the aggressiveness of the product rather than go to a very aggressive pad
3. Always finish with the next lower level of abrasive i.e. after using a compound polish #1(800 -1000 grit) continue with polish # II (1200 grit) and then polish # III (1500 grit) and finally a IV 2000 grit or # V 2500 grit polish, whatever grade you start with always finish with a the least abrasive polish
4. Changing the diameter / size (surface area) of the pad increases its abrasiveness by concentrating pressure
5. Using a rotary polisher and 800 -1200 grit removal polish / compound; after two such processes restrict future polishes to 2000 – 3500 finishing polishes and perhaps start using a glaze rather than polishing.
6. Polishing; friction heat is required to breakdown diminishing abrasives, heat (a by-product of friction) is required to outgas (flash) the solvents, best practice dictates a wipe-down of the paint surface to remove any residue oils from the surface to ensure that they are not filling any micro marring, and to inspect the paint surface to ascertain if further correction is required. (See also Comparative Abrasive Scale (CAS), Machine Polish / Foam Pad Combinations, Polish)
7. (Loading) the build-up of sanding debris between the abrasive particles on finishing paper or sanding discs during use; this reduces the cutting effectiveness of the abrasive.
Information resource
- "Automotive Detailing Inside & Out, A Knowledge Base for the Perfectionist"– by Jon Miller
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