Diminishing Abrasives

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Diminishing Abrasives:

Orbital and dual-action polishers can be safely used by the weekend enthusiast, show car owner or professional detailer without fear of damaging the finish. If you're experienced in machine polishing, our professional rotary polishers will allow you to remove deeper scratches, swirls and paint defects. If you've been detailing your car by hand, consider stepping up to a machine polisher. You can not duplicate the friction required to adequatley break-down diminishing abrasives unless you use a machine polisher that has sufficient torque.

Diminishing abrasives require friction, not heat (that is just a by-product of friction) to activate and progressively reduce there size until they become a finite milled dust; they are buffered or cushioned in a lubricating water-based oil film emulsion, usually in a semi-liquid paste. Wet polishes eliminate the heat caused by buffing; heat causes gloss loss. Some very abrasive compound polishes don’t feel abrasive to the touch because the particles are formulated in a solvent or polymer oils in a water-based emulsion and are not released without friction. The abrasive start off as large particles, which removes the most paint, they are then reduced in size into finer and finer particles, removing progressively less of the paint surface, by the friction caused by the foam pads contact with the paint surface. By varying the size of the abrasive a differing cut is obtained, so the more the abrasives are reduced in size the finer the resultant finish until the particles are reduced to a very fine powder, which in turn produces a burnished surface shine.

The amount of size reduction (diminishing) can be adjusted by the type of abrasive material used (silica and /or aluminium oxide) allowing some polishes to used for the removal of surface scratches only, but if required can then followed up with a finishing type polish that contains smaller abrasives. Were as some polishes will remove surface scratches and by changing the abrasive ability of the foam pad will then go on to buff the surface to a shine ready for the application of a last step product (LSP)

• Difference between Diminishing and Standard Abrasive Polishes - While the majority of polishes on the market use a form of diminishing abrasive, which you polish to a ‘haze’ (when a polish "flashes" from a liquid paste to a light semi-dry haze) the diminishing polish has then broken down and is ready for removal. It is important to know when a polish has broken down because if you take it too far you will re-introduce surface marring. Some products use standard cutting abrasive that provides a constant cutting action throughout the polishing process. Unlike diminishing abrasives, which require time and friction to enable the abrasives to 'break-down to obtain the best possible finish (and avoid holograms) standard abrasive polishes should be used with a cutting foam or wool pad until the defects are removed (1200 – 1500 RPM) but do not allow the polish to completely dry (as this will also produce holograms)

Heat - the temperature of a paint surface should be monitored when using a high-speed polisher, as friction heat can cause a rapid spot temperature rise (i.e. initial surface temp 80oF, heat attained by applying a cutting foam pad machine polish at 1,100 RPM for approx. ten seconds, 104oF) the paint temperature should be limited to 100oF (115oF <) in accordance with the Society of Automotive Engineers (SAE) Temperature at this level cause the urethane clear coat to soften and the foam pad will cause scratching that is forced deep into the clear coat

Polishing - can be cutting (an abrasive process) or polishing, (a burnishing process), since the polyurethane is a thermo plastic, generation of excessive heat may cause the molecular structure to soften or expand driving the defect deeper into the substrate

Menzerna Professional polishes will not finish up dry, but will always have a hazy film to them. Polish to a ‘haze’ - when a polish "flashes" from a liquid paste to a light semi-dry haze; its colour changes from the polish colour to almost transparent; the polish has then broken down and is ready for removal. The point at which a polish is fully broken down comes with experience but a good yard stick is when the polish has become clear and can easily be wiped off.

It is important to know when a polish has broken down because if you take it too far it will dust and you will re-introduce surface marring, conversely if you don’t work diminishing abrasives sufficiently they will cause surface marring; this is due to the size of the abrasive and its cutting ability, were as once an abrasive has broken down it will burnish the surface as opposed to cutting it

Menzerna have been producing this type of abrasive for use by OEM’s and has the most experience with this technology. They mill there own abrasives to ensure quality control within a size range of approx. 0.3 –0.4 µ (micron). The most common abrasive used is silica however; many formulators are also using aluminium oxide. Most good compounds and polishes contain diminishing abrasives and are a combination of both silica and aluminium oxide. Think of them as liquid grit finishing paper, they are formulated with a lubricant (polymer or solvent / oils in a water-based emulsion)

Most good compounds are a combination of both silica and aluminium oxide. The abrading ability of these compounds can be changed by their application method (i.e. machine speed and/or pressure used, using wet or dry and/or type of foam (different foam compositions have a differing abrading ability) Allow sufficient time for the polish to work, with a more aggressive polish a longer time period is required (approx 3 – 6 minutes)

The speed at which the foam pad travels across a paint surface is also important, moving too fast won’t allow the micro-abrasive to ‘beak down’, Machine linier speed; machine left to right movement shown as inches per second (IPS) apply polish at an MLS of 3-inchs per second with a rotary polisher (1.0 to 1.5-inch per second random orbital buffer).

Product specific-Menzerna Professional Polishes- are foam pad ‘dependant’ as far as its paint correction abilities are concerned and they appear to work better when the foam pad is ‘primed’ (Priming a pad - a light misting with distilled water) I would recommend a two level foam pad / polish system to really heighten the paints finish shine.

These polishes were designed to work in the controlled temperature / humidity environment of a vehicle manufacturer’s paint shop finishing line, so be aware that working outside you may have issues like excess humidity, heat, cold, etc that will affect there performance especially with the Nano polish (105FF) as it uses wax as a lubricant (colder temps may cause the wax to harden) 3M Ultrafina is a good back-up in colder temperatures

Information resource -

• "Automotive Detailing Inside & Out, A Knowledge Base for the Perfectionist"– by Jon Miller