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#1
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"Sandblasting and Restoration" Going to bare metal
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Quote:
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#3
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Don't sandblast your car, it is too hard on the metal. You can get it blasted with little plastic beeds, this will remove the paint but will not harm the metal.
Brg, Karsten |
#4
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I have heard meny say that you can not sandblast the body panels of contemporary cars as it will/can bend, heat, warp the metal. is that always the case, or just in the inexperienced hands of a green operator, with to much air pressure being used. (btw I would qualify as the above stated 'green' operator) Yet the question remains as to how else to remove rust from the under body, rear fender wells, bottom inner lip of doors, with out spending a fortune at the body shop...? And still be sure that all the rust was removed??
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46 WDX Power Wagon 84 300TDT daily driver |
#5
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Hi Folks,
Sandblasing the undercarriage, wheel wells, door jambs, etc. is fine, but blasting the exterior panels of any vehicle, regardless of whether it's vintage metal, which is normally a heavier guage, or the newer stuff sh0ould always be avoided. Heat is not the problem. That's a myth. It takes very close to 600 degress F in a localized area to create distortion from heat. What happens in this instance is that the heat causes the metal to expandand since it has no place to go, the forces involved of the expanding localized area of metal pushes itself into the surrounding cooler metal. When it all cools to the same temperature the heat affected zone had in effect become shrunken (less surface area than what it was originally. Sandblasting does not create that amount of heat. The trouble lies in the amount of pressure being applied by the millions of particles of sand peening the surface of the low crown panels. There isn't enough strength to withstand the abuse and the metal looses the battle and begins to stretch as a result of the peening action. Even high crown panels of vintage automobiles can be affected by this, although not normally as noticable, nor as critical. I've seen many body panels absolutely ruined as a result of sandblasting and would not advise it, even if the operator "claims" to know what he's doing. As I said, it's fine for areas where there is sufficient strength to withstand it, as it will cut down on several hours of cleanup time in those hard to get to areas. As for the plastic media blasting, I've seen it stretch low crown panels as well. For the most part, it seems to be more forgiving than sandblasing, but still a risk involved. Soda blasting is also a popular method, but be very careful toi cleanup the residue left behind before refinishing. This residue will prohibit your primer from bonding to the metal ans you will have a real mess on your hands when the paint starts blowing off in large sheets. It's always a good idea to sand all area to be repainted with 80 grit sandpaper where possible and a red scotchbrite pad in those hard to sand areas. For optimum corrosion resistance and adhesion, a high quality epoxy primer is the best coating available for use on bare metal. I've been a professional painter for nearly 20 years and the best I've found is available from Southern Polyurethanes Inc. www.southernpolyurethanes.com John, My recommendation would be to remove all the trim, door handles, lights, bumpers, etc. Wash the body thoroghly with hot soapy water (Joy dishwashing detergent works great) Get everything you can, door jambs, underside of hood & decklid, etc. This will remove water based contaminates that Wax and Grease remover will not get. The next step will be to use a good wax and grease remover to kill any remaining contaminates. Follow manufacurers directions for application and clean-up. Any areas that need aggresive sanding, such as rock chips, scratches, etc. should be feather-edged with 180 grit paper on a DA sander. If you have dents that need repaired, those should be taken care of as well and if you need to use body filler, make sure to prime those areas before going on to the next step. It's best to use epoxy primer over bare metal areas prior to applying body filler as well as applying two coats of epoxy over the top of filler. I prefer to metalfinish everything, so filler is not needed, but it takes several years of practice to master that, so I understand is you need to use filler. Once you have the repairs made, get a fresh bucket of hot soapy water and 600 grit wet/dry sandpaper and sand the entire area you plan to refinish. You do not need to remove the original paint. In fact, it's the best base you could hope for. You will remove most of the oem finish as you sand with the 600 grit anyway, as there will only be a very thin layer of it left at best. The oem primer is what you really don't want to go through as it has a great adhesion to the metal and has great corrosion resistance. After sanding the car completely with 600 grit, get another fresh bucket of hot soapy water and use a good amount of Ajax with a red scotchbrite pad. This will get any area's you may have missed with the sandpaper and will have the body ready for a fresh paint job. Make sure to rinse the body several times to get rid of any sanding sludge that may be lodged in hard to reach areas. This will have the car ready for the painter or if you decide to do it yourself at this point, you can simply mask it off and go over it one time with a final wash solvent prior to painting. A good wipe down with a tack cloth and you'll be ready to paint!! Good luck with it. Randy Ferguson Ferguson Coachbuilding Robinson, IL. Last edited by Randy Ferguson; 05-15-2006 at 07:33 PM. |
#6
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Wow, thanks Randy. I will print that page and take it to into the shop with me for refrence.
Jason
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46 WDX Power Wagon 84 300TDT daily driver |
#7
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Hi Guys,
Here's a little more reading material for you if you need a more in depth approch to the process. A friend of mine, Kerry Pinkerton, wrote this on the Imperial Club forum a few years ago. He had sent me an e-mail asking for advice, and after several messages between us, he added our question and answer sessions to his saga, so rather than re-writing most of it, you may refer to it here: http://www.imperialclub.com/Repair/Body/Painting101/index.htm I think between the both of us, we pretty well covered everything. If anyone has any questions, feel free to ask. Randy Ferguson Ferguson Coachbuilding Last edited by Randy Ferguson; 05-15-2006 at 07:38 PM. |
#8
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There are a LOT of other materials to blast with now other than "sand", including some manufactured materials. Some are absolutely safe for a car body and will not even remove rust (baking soda, for example).
__________________
86 560SL With homebrew first gear start! 85 380SL Daily Driver Project http://juliepalooza.8m.com/sl/mercedes.htm |
#9
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Saw a note praising Mercedes own brand of body filler. I need to know what is a good filler to work with on my 69 280 SE. If anyone can recommend a brand of filler for some fairly rusty spots, please post here or drop me an email at bbfloor@gmail.com.
Thanks, Bill Banks in nY |
#10
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Thanks for all the info, Randy. I have no intention of ever doing all that myself, but it's great to know for when I'm looking for a shop to repaint my car.
__________________
" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century ![]() OBK #55 1998 Lincoln Continental - Sold Max 1984 300TD 285,000 miles - Sold The Dee8gonator 1987 560SEC 196,000 miles - Sold Orgasmatron - 2006 CLS500 90,000 miles 2002 C320 Wagon 122,000 miles 2016 AMG GTS 12,000 miles |
#11
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I've heard of blasting bronze sculptures with things like pecan and walnut shells and other things like that. Are there materials like these that are using in cleaning paint off of car bodies other that sand or plastic beads? How hard is it to do this type of work?
__________________
" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century ![]() OBK #55 1998 Lincoln Continental - Sold Max 1984 300TD 285,000 miles - Sold The Dee8gonator 1987 560SEC 196,000 miles - Sold Orgasmatron - 2006 CLS500 90,000 miles 2002 C320 Wagon 122,000 miles 2016 AMG GTS 12,000 miles |
#12
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Take a look at this thread
Welcome to the forum, John It will talk about the disadvantages of removing all the paint when repainting--both from a quality and safety standpoint. Except in extreme cases, you never want to remove all of the original paint.
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___________________________________________ 2010 Toyota matrix '93 500 SEL A bad addiction. Takes all of my cash. '12 Volvo S80 T6 Needed something that wasn't as hard to deal with as my bad addiction '18 Mazda Miata No more boring cars for everyday transport! |
#13
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Also keep in mind that for non-trivial blasting, regardless of the media used (entire panels and not small spots), it takes a LOT of air. You need a heck of a compressor to do this - And it makes a LOT of noise.
__________________
86 560SL With homebrew first gear start! 85 380SL Daily Driver Project http://juliepalooza.8m.com/sl/mercedes.htm |
#14
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IMHO I would leave the OG paint as a good base if it's not rusted. Rust areas I would get down to bare metal then treat with Phosphate and Etch or a similar product the kill any cancer.
I have blasted a lot of stuff with both a pressurized blaster and the blaster in a bucket type blaster. I personally hate the mess. Seems like you never get rid of all the sand, beads, or what ever you use. It's great for wheels and small parts, especially in a blast cabinet. Aircraft Stripper is the best I've found for stripping paint. Just make sure you clean the metal well after the paint is gone. |
#15
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Makes sense to me that, if possible and indicated by the condition, it would be better to save the underlying factory primer, because of quality, adhesion, etc, and remove some/as much as necessary/all of the top paint layers, then repaint. Seems to me it would be nearly impossible to duplicate the electrophoretic primer applied by dipping the body, then the primer applied in a near-surgical environment, just to replace aged and sun-damaged top layers. To each his own, though. Whatever satisfies you.
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