Polishing by machine opens up more possibilities in comparison to polishing by hand, as products can be worked much harder and for much longer with ease. For example, many popular dual action machine polishers have a maximum working speed of approximately 6000 orbits per minute. It is impossible for a human being to replicate this work rate; just imagine trying to polish a panel in a circular motion 6000 times a minute for 5 minutes or more, all the time applying constant pressure! Because the work rate is also selectable, machine polishers can be used to safely tackle all forms of paint defects, ranging from minor swirl marks to very deep scratches. The only proviso is that the clearcoat must be intact before starting, and must not be reduced to less than 75% of its original thickness as a result of polishing. A further benefit of polishing by machine at high work rates is that painted surfaces can be burnished to an exceptionally high lustre prior to the application of sealant or wax protection; the same quality of finish is very hard to achieve when working by hand. Although machine polishing offers many advantages over working by hand, it also adds complexity to the polishing process. This is because additional choices have to be made with regard to machine type and pad selection. These choices are critical, because if you get them wrong it is very easy to damage your paint; machine polishers can remove paint surprisingly quickly if not used correctly. Let's start with the choice of machine type. Machine polishers fall into one of two camps; rotary or dual action. Rotary polishing machines are usually the choice of professional detailers. As the name suggests, the polishing head rotates evenly around a fixed point at speeds of up to 2500 revolutions per minute. This circular action creates a lot of friction that can be used to great advantage when correcting major paint defects. However, the downside of this is that is it also very easy to inflict damage in the form of burn marks, buffer trails and excessive paint removal. Mastering the art of rotary polishing takes a lot of practice and for this reason I do not recommend it unless you seek professional training first. Dual action machine polishers work very differently to rotary polishers, in that the polishing head oscillates randomly about a fixed point as the polishing head spins (hence the term dual action). What this means is that friction is vastly reduced at any given point of contact, limiting the effective work rate and greatly reducing the risk of burning the paint or removing too much of the clearcoat. Because of this, dual action machine polishers are ideal for enthusiasts who want to be able to safely correct their paint without the fear of inflicting further damage. A common myth is that dual action polishers are much less effective than rotary polishers. Whilst it is true that extremely serious paint defects can often only be fully corrected by rotary polishing, it is also true that dual action polishing can usually correct all but the most serious of defects on most paint types. The major difference is the time taken to perform the correction; a job that might take under an hour with a rotary polisher may take several hours or more with a dual action polisher due to the lower effective work rate, but in most cases the end result will be similar. Now we can see why it pays the professional detailer to master the art of rotary polishing, and why dual action polishing is the safe alternative for car care enthusiasts. Pad selection is another critical choice when polishing by machine. All pads designed for use with dual action machine polishers are made from varying grades of high quality flexible polyurethane foam. The firmness of the foam dictates its suitability for different polishing tasks (compounding, polishing, glazing) and is usually colour coded to make recognition easier, although manufacturers rarely use the same colour schemes, so always read product descriptions carefully. Compounding pads are made from the firmest foams and are usually non-reticulated, which means that the foam was not thermally expanded during manufacture and therefore remains very firm and dense. This allows such pads to cut into the surface of the paint quite easily, and they should therefore be used with care. Polishing pads are made from foams of intermediate firmness and are usually reticulated, meaning they are more flexible and adaptable than compounding pads. Such pads have a very slight cutting action that allows them to correct minor defects without removing too much paint. Glazing pads are made from much softer foams and are always fully reticulated. Such pads have no cutting action but are capable of burnishing paint to an exceptionally high lustre. Even softer foams are now available for applying liquid sealants and waxes too. In addition to the firmness of the foam, pad designs also vary in size and shape, ranging from small, flat pads to large, variably contoured pads. Small spot pads varying from 80 mm to 100 mm in size are designed to be used with 75-90 mm backing plates, and serve two main purposes. Firstly, they allow access to awkward areas, such as around grills and wing mirrors. Secondly, they allow specific defects, such as scratches, to be worked harder, as their size means that all of the polishing effort is focused on a smaller area. As an additional benefit, their size also means that less surrounding paint is affected during the process of scratch removal. Larger pads typically varying in size from 135 mm to 165 mm are designed to be used with 125 mm backing plates, and are ideal for general polishing tasks and working on larger panels. In the past, pads were always flat, but recent advances in design and technology have resulted in the release of shaped pads onto the market, which are sometimes easier to control. The most advanced pads currently available feature variable contour and constant pressure technologies, which provide greater flexibility in the form of multiple polishing faces and additional safety in the form of foam layers that help to keep the polisher level during use. Now that we have examined all of the choices surrounding machine polishing, we should be able to determine safe approaches to defect correction. In all cases, the first thing you should do is ensure that your paint is spotlessly clean and dry; wash your car first and then decontaminate it if surface contamination is evident. In order to correct serious paint defects, such as severe swirl marks and acid etching, we recommend that you first try using a polishing pad in conjunction with a medium abrasive polish (the exact choice should be made with due consideration given to the hardness of the paint being polished; this topic is covered in detail in our guide entitled "What polish should I use?"). This combination can be worked hard at high speed without fear of removing too much of the clearcoat. If after several applications the defects still persist, you may want to consider swapping over to a cutting pad and a heavier polishing compound. However, such action should not be taken lightly and ideally only if you are experienced at machine polishing or have sought advice from an experienced person first. If you decide to proceed, always work in a well lit area, check your progress after every attempt, and keep the working speed below 5000 orbits per minute. Once you have removed the defects, check the quality of the finish. If you can see any marring you will need to conduct another polishing step, this time using a polishing pad in conjunction with a finishing polish. We recommend that the same combination is used to tackle less severe paint defects such as minor swirl marks and fine scratches. If after several applications the defects still persist, you can then try a medium abrasive polish (applied using a fresh polishing pad; you should never mix products on the same pad). The pattern you should see emerging here is very simple; always use the least aggressive product you can to get the job done, and always match your choice of pad to the task in hand. The process becomes even more straightforward if your aim is to simply mask any remaining defects or burnish the finish in preparation for sealant or wax protection; simply use a glazing pad to apply a suitable choice of glaze. When it comes to the actual polishing process, the technique is similar whether working large areas or specific defects. In the case of the former, the first thing you should do is mask off all trims using low tack masking tape. This is because it is hard to avoid running onto trims when using large pads, and failure to cover them often results in staining that is subsequently time consuming to remove. The second task is to choose a suitable pad and product combination for the task in hand. Then you should fit the backing plate to your polisher, press the pad in place (making sure you centre it on the backing plate) and connect the electricity supply. We recommend using an RCD safety device and an extension cable, so as to allow all panels to be easily and safely reached. Now you are ready to start polishing. Before you do, you should prime the pad; this means adding a little lubricant to the pad, so that dry buffing is avoided before the polish has time to spread. The easiest way to prime a pad is to mist it once with a quick detailer. The next thing to do is apply three to four drops of product to the pad; this is more than sufficient in most cases. With the pad primed and loaded with polish, the next thing you should do before switching your machine on is spread the product across the work area by pressing it repeatedly against the panel; this subsequently helps to ensure that all parts of the work area are evenly polished. Try to work 2 ft x 2 ft sections at a time, starting on a panel clearly featuring defects you want to correct (this allows you to quickly determine if your choice of pad and product is going to achieve the desired result). With the pad held against the paint, you can now switch the machine on. I recommend that you read the instructions supplied with the machine before you first use it, paying particular attention to the section on safe working practices. When you start polishing, you should make an initial pass over the whole work area at a low speed setting (2-3 on the dial of most dual action machine polishers) in order to allow the product to spread out evenly across the pad and the panel. Time to tackle the deeper scratches left in the bonnet Only a few drops of a medium abrasive polish are required per 2 ft x 2 ft area The polish should be dabbed onto the panel and then spread at low speed After completing this initial pass at a coverage rate of 4 - 6 inches per second, you should turn the speed up (4-5 on the dial of most dual action polishers) and then move systematically across the panel, applying light to moderate downward pressure. Slow, overlapping passes are ideal; there is absolutely no need to move the machine rapidly backwards and forwards or side to side. Different products need different amounts of work before they are ready to be removed, and knowing when this is the case only comes with practice (although a good rule of thumb is that most allow you to go over a 2 ft x 2 ft work area at least three dozen times before they are ready to be buffed off). A good indication is a change in the appearance of the polish residue; many appear to become transparent when they have been properly worked and broken down. You should always stop the machine with the pad held against the paint. Many product residues are a little bit stiff, and their removal often necessitates firm but careful buffing with a microfibre towel. Plush towels with a short nap are ideal for this, as they are kind to the finish yet have sufficient bite to lift polish residues with ease. Once the residue is removed you should inspect the panel and repeat the process if defects still persist. The polish should be worked methodically in an overlapping pattern at high speed After a few dozen passes the polish will start to turn clear as the abrasives breakdown The result; complete removal of the scratches, leaving a perfect high gloss finish When polishing out specific defects, such as serious scratches, the technique is essentially the same, but the choice of pad will differ. To remove a specific defect like a deep scratch, it is better to use a spot pad, as they concentrate the polishing effort and affect less surrounding paint. In this case the scratch wasn't deep enough to catch a fingernail, so we were confident that we could safely remove it by lowering the level of the surrounding clearcoat. After setting the machine up and fitting a smaller sized backing plate, I primed the pad with a shot of quick detailing spray and then loaded it with a medium abrasive polish. I then spread the polish evenly over the work area by pressing the pad against the panel repeatedly. This scratch came free with our shopping one week at our local supermarket Polishing pads should be primed before use with a quick mist of quick detailer A little bit more polish than usual is used when focusing on deep localised defects Now ready to start polishing, I held the pad against the paint and turned the machine on, using a low speed setting (2 on the dial). I moved the pad over the work area applying only light pressure for a minute or so, in order to allow the product to spread out evenly across the pad and the work area. Then I increased the speed (4-5 on the dial) and began to move systematically back and forth across the work area, applying moderate pressure. After a few minutes the product started to turn transparent, so I switched the unit off with the pad held against the paint and then buffed off the residue with a plush microfibre towel. Whilst this first application greatly lessened the severity of the scratch, it was still clearly visible. I then repeated the process, this time applying firm pressure and using the machine at high speed (5 on the dial). After the product once again began to turn clear, I turned the machine off and buffed off the residue. A close inspection revealed that only the faintest trace of the scratch remained, so instead of repeating the process I decided to apply a glaze and then apply multiple layers of sealant protection. The polish should be dabbed on and then initially spread at low speed .photobucket.com/albums/pp234/b0dyr0ck2006/washing%20technique/b64b90f2.jpg" alt="" /> Once spread, the polish should be worked at high speed with moderate pressure After two attempts, a coat of glaze and a topcoat of sealant and the scratch is gone The final step in the polishing process is to pack away all of the tools you have used, making sure everything is clean and ready for next use. All towels and applicator pads should be washed in a washing machine at a low temperature using a non-biological liquid detergent (avoid soap powders and detergents containing bleach or fabric softeners) before being allowed to dry out naturally. All polishing pads should be scraped off using a blunt plastic edge and then rinsed out thoroughly under the tap before being left to soak for 10 - 15 minutes in a bucket of pad cleaning solution. After 10 - 15 minutes is up, the pads should be rinsed out thoroughly and then left to dry out naturally. On to Waxing: http://thelatebay.com/index.php?topic=11709.0
