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The Auto Painting Tips Newsletter
With Chris Curwen & Expert Auto Painter - Dave Gage (Car Cosmetics) November 7th, 2007 - Issue 28 In this issue:
Clear Coat Clear coat is exactly what it says on the tin: Clear. You would spray automotive clear coat over the top of certain types of color coats. This would serve as a protective film which you could then polish to perfection without disturbing the underlying base coats of color, pearl or metallic. In the past, automotive clear coat was used almost exclusively over lacquer paint jobs. This was because polishing lacquer color coats could disturb the evenness of the color. Clear coat also added resistance to harmful sun rays and potential paint finish hazards. Today, automotive clear coat is commonly found on many stock factory paint jobs. Working with Clear Coat: Mixing You would mix automotive clear coat with an environmental specific reducer/thinner rendering it sprayable, and with a hardener to increase its durability and gloss. Using a MS (medium solid) system clear coat, mix using the ratios 2:1 = 2 parts clear coat : 1 part hardener plus depending on the environmental temperature anywhere between 5-10% of reducer/thinner. How to Spray Auto Clear Coat For a visual demonstration on how to spray auto clear coat, please refer to How to Paint a Car - The System - Parts 1 & 2 where we provide you with specific videos on how to spray auto clear coat. Drying Depending on your painting circumstances, you would be best using automotive clear coat products that are designed to be air-dried rather than products that are designed to be used in a downdraft professional spray booth. However, if you plan on renting time in a downdraft spray booth, you won't have any limitations over which product you can use. Custom Paint Jobs Custom paint jobs almost always call for protective coats of clear paint. This is so polishing and waxing will not directly touch or adversely affect the exotic color blends, metallic flakes, pearl additives or custom graphics. In addition, certain clear coat products contain chemical ingredients that are designed to reduce the harmful effects of ultraviolet sun rays and help color coats resist premature fading. If you are planning on customizing the paint finish on your vehicle (paint finish customization is a separate topic entirely that warrants its own section, meaning we cannot cover it right here) there is a vital rule that you must abide by. Let me explain, you see the compatibility of every product in the paint system is very important, whether in regard to the surface on which it will be applied to or among the different products used in the system. There are many individual products which were not designed as part of a single compatible paint system that can have adverse effects to the color, adhesion and surface flow of that combination. Therefore you will need to determine the type of material on the vehicle surface - enamel, lacquer or urethane, before you buy the paint for your vehicle. In the case of newer vehicles, all factory paint jobs are going to be urethane based, as enamels and lacquers are being left behind. To discover whether your vehicle has been painted with a base coat clear coat system for example, take the color code numbers from your factory painted car to your local auto paint supply store. The information that they have on file in their paint books or computer database will quickly tell you what system was applied. If your vehicle has been repainted since leaving the factory however, you will need to sand an inconspicuous spot with 600-grit or finer sandpaper. A white powder residue is an indication of clear paint in most cases. If however, your vehicle is white, this method will be somewhat more difficult. In How to Paint a Car - Part 1: Auto Scratch Repair - Part 1, you will see that soon after the paint technician begins sanding down the scratch, a white sanding residue begins to form on the area of repair. This is a clear indication that the vehicle has indeed been painted with a base coat clear coat paint system. Multi-stage Systems In the past, vehicles were primed and then painted with single-stage paints. There were no clear coats to protect the color, metallic or pearl additives. Plain, solid colors, offering little protection (other than manually applied wax) were the common way of doing things. For the majority of cases, automobile factories have gotten away from single-stage paint systems. By using multi-stage paint systems, they can provide a wider variety of color effects, whilst providing a more durable paint finish. It was simply a case of the auto paint industry moving forward. Base Coat Clear Coat Systems A base coat clear coat paint system is also sometimes referred to as a two-step paint system:
Base coat (the color) is mixed with a reducer/thinner appropriate for your painting area temperature, rendering it sprayable. As previously mentioned, clear coat is mixed with a reducer and a hardener to increase gloss and durability. How to Paint Base Coat Clear Coat. The best demonstration we can give you of a modern day base coat clear coat paint system being applied to a damaged area on a vehicle is by referring you to How to Paint a Car - Part 1, Sections 22-24 which cover 'Auto Scratch Repair' as a 3 part series. Check it out right now! In theory, base coat clear coat paint systems are the modern day equivalent of the old practice of spraying lacquer color coats and then coating them with additional coats of clear. The base coats of color are applied to achieve coverage (the number of coats necessary differs with each color.) After obtaining coverage, you would apply two to three coats of clear. You would then need to sand and buff the clear coats to achieve a superior shine. Why the need for Base Coat Clear Coat Paint Systems? There are two commonly referred to reasons why base coat clear coat finishes were introduced: 1. The application of clear paint over light-colored metallic paint finishes greatly increased their durability. 2. The process reduced the solvent requirements for the paint color applications which helped manufacturers meet the government's emission standards. In brief, base coat clear coat paint systems will permit you to apply only a 1 millimeter thickness of color, covering it with 2 millimeter's of clear. Conventional paint color applications normally call for thicker coverages of 2 to 3 millimeters. Base coat clear coat paint systems have clearly become the favorite of contemporary custom painters, and with their ease of use, they are highly recommended for auto painting beginners as well. If you can accurately mix the ingredients, urethane base coat clear coat paint systems are as easy to spray as lacquer and more durable than enamel. Tri-stage Paint Systems Some new colors may require three stages - a fact that can be determined by color code deciphering or paint chip selection at an auto paint supply store. How Tri-stage Paint Systems work? A base coat of gold, silver or white for example could be applied before toner's or another color is sprayed on top. The result is that the base coat will always show through at varying degrees depending on the number of layers of toner; toner's are a light mixture of color blended in with clear paint. The final semitransparent effect is described as translucent. The desired final finish color along with the paint system brand selected, will determine what base color must be applied to achieve the intended results. Application guides available at auto paint supply stores list recommended flash (dry) times between coats and any other critical information regarding the use of that particular paint system. The third and final stage of this paint system is the application of clear coat. With this type of system, wet sanding, rubbing out or polishing a color coat that has been applied over a base coat could remove enough color pigment to cause parts of the base coat to show through, thus creating a break in an otherwise uniform paint application. Therefore, coats of clear paint not only protect underlying color coats, but will allow you to buff and polish surfaces to a deep, lustrous shine without ever touching the color. Who should paint using tri-stage paint systems? Although base coat clear coat paint systems are highly recommended for novice auto painters, the use of a tri-stage paint system is not recommended. Tri-stage is an advanced auto painting technique, unsuitable for rookie auto painters. Why make life difficult when you're first starting out? With the number of variables associated with painting, such as mixing paint, application procedure and correct time between coats, the addition of a third stage variable would increase the chances for error quite dramatically. To Conclude... If your vehicle is scheduled to be stripped to bare metal and you are contemplating a complete paint job, you can use almost any paint system. This could be single stage urethane for relatively easy two- to three- coat coverage with no rubbing out or buffing requirements. Or a complete base coat clear coat system that will mean more spraying and rubbing out work, but a much more durable and bulletproof finish. Preparations will basically be the same. You'll have to treat bare metal to coats of epoxy primer and primer and then sand them to perfection before applying either a single-stage or multi-stage system. Always consider you safety first. Concerns over personal safety while using hardeners with isocyanate ingredients may prevent you therefore from using clear coats and opt for a single-stage product. If this is the case, since small specs of dirt or debris cannot be wet sanded smooth, you will have to apply paint in an extra-clean and dust-free environment. Extra help is available. By far, your best source for product information is from your local auto paint supply store member of staff. This person is trained to address concerns about your car's existing paint surface, any special mixing or application techniques unique to the new paint system you have chosen and any local climate and weather conditions. Prepare a list of questions before you visit, they will be able to help you in all areas. ******************************************************************************** That's all we have for you this week. Thank you very much for reading. We both hope this issue has been of valued interest to you. COMING NEXT ISSUE: We look into the importance of using Wax & Grease Remover and Tack Cloths. Happy Painting! Chris Curwen & Dave Gage www.LearnAutoPainting.com © 2007 LearnAutoPainting.com
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