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The Auto Painting Tips Newsletter
With Chris Curwen & Expert Auto Painter - Dave Gage (Car Cosmetics) November 27th, 2007 - Issue 31 In this issue:
There are indeed various types of paint removers that come in bulk and in aerosol form that are available to you for removing paint. Some of these paint removers will be more effective than others depending on the situation in which you are using them. Others may cause surface damage to the material being stripped if not used on a compatible surface. Always be willing to discuss your particular application with an expert at your nearest auto paint supply store in order to obtain the best product for your specific need. How is paint removed from the surface of a vehicle? Auto Paint is removed from vehicle bodies in one of three ways:
If the paint that has to be removed has been neglected at any time, there is a good chance that rust will have affected the surface of the vehicle. If this has happened, it will likely require media blasting to remove it. Both sanding and media blasting will remove not only the paint but also any undercoats and anything else attached to the bare metal. Chemical strippers, which will also remove paint down to the bare metal, work by loosening paint material so you can gently scrape it off with a plastic squeegee or a putty knife. Chemically stripping paint from a vehicle isn't a clean practice with wet lumps of paint simply falling onto the floor as they're scraped off the vehicle surface. Personal safety while using potent chemical strippers must be at the top of your list of priorities. Heavy-duty rubber gloves must be worn along with eye protection and a respirator as instructed by all product labels. Chemical strippers are commonly used when undertaking a complete new paint job rather than for repairing localized damage and touching up. Sanding An electric or pneumatic sander works very well on small projects or localized repairs. Using a sander makes it is very simple to remove paint from the immediate area that will require undercoat and paint application. You will want to use 36- to 80-grit sanding discs for speed and efficiency. If you wish, you can also use extra-coarse sanding discs to do a good job for you of removing all paint and/or body filler remnants from any tiny dents and other hard to reach places. Don't worry about the deep scratches that you leave behind on the surface of the metal as you sand away, these will serve as an excellent base for filler materials to bond onto. Please refer to Issue 06 for further details on the process of paint removal by sanding including the ideal sanding kit to aid you with your sanding progress. In addition, as part of our Auto Painting solution: How to Paint a Car - The System, we cover paint removal by sanding in four parts. For you benefit, we have included one of those parts on our homepage as part of our sample training video series. Go there now to see the professional demonstration of paint removal by sanding. Media Blasting Media blasting is one of the more ideal paint removers other than using a hand-held sander, if for example you were working on a small removable part from a vehicle or a full body-off restoration. Media blasting would indeed be a much more efficient way of removing paint and any underlying primers from a complete body shell or a chassis. There is a down side however to both media blasting and when using a hand held sander. Using either method, if you focus your attention within that area for too long, friction will cause an excess of heat to be generated causing the sheet metal to warp. You would then have to repair this area before you can continue preparing the vehicle for paint. One other drawback of media blasting is that on a car body or truck cab, it is virtually impossible to remove all of the blasting media that accumulates between panels and within crevices. Some of this blasting media will eventually fall into your paint or interior upholstery, but will never be completely removed from the vehicle. On the flip side, a benefit with media blasting is that when using the correct media and under the correct air pressure, it can be used on fiberglass or other non-sheet metal components. If you are planning on carrying out the media blasting yourself, double check with your nearest auto paint supply store on your intended equipment set-up to make sure you haven't made any miscalculations. If you aren't going to be the one who does the media blasting, then check to make sure that the one who is knows exactly what media there is available and the correct usage for it. Chemical Stripping Chemical paint removers work very well on vehicles in need of a complete new paint job with the body being in almost perfect condition. You would use chemical paint strippers when there is no reason to roughen sheet metal with a sanding disc or risk making a mistake with sand blasting equipment, causing panels to warp or otherwise be damaged due to high-pressure media blasting. Even though chemical strippers can easily damage non-metallic items such as rubber moldings or plastics, if you abide by the recommended application methods and adopt a gentle material removal approach, you should be left with a clean, shiny body surface without any ill effects. To reduce the possibility of further scratches or other scraping damage, you may wish to consider using a heavy-duty plastic squeegee to remove wrinkled paint from body surfaces, instead of a metal putty knife. In order to find out which brand of paint remover is best suited to your specific needs, seek the advice from an auto paint supply store salesperson. Stay Clean It is always in your best interest to keep your work area as clean as possible at all times. Therefore when using a chemical paint stripper, use a sheet of heavy-duty plastic or cardboard under the edges of your car while removing chemically impregnated paint residue. By doing this, once the body is stripped, you can remove and discard the scrapings safely according to any local hazardous waste control regulations in effect in your area. What form do chemical paint strippers come in? Chemical strippers are available in two basic forms:
When the full vehicle body will be removed from the chassis, dipping would be a practical way to remove all paint and primer. For the best results, everything to be dipped should be disassembled as completely as possible. This will permit the chemical stripper to get into all of the places where rust may be hiding. This process removes all rust, leaving only shiny metal. Bear in mind that if a band of rust is all that is holding the lower portion of a door for example onto its upper portion, the lower portion will very likely no longer be attached when the parts are lifted out of the rust removal chemical. Brushing Brushed-on chemical strippers should be reserved for relatively small jobs, such as a door. Doing an entire vehicle by hand would be more expensive than disassembling it and having the components dipped. ******************************************************************************** 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 cover the undercoat, Primer. Happy Painting! Chris Curwen & Dave Gage www.LearnAutoPainting.com © 2007 LearnAutoPainting.com
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