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  • Paint and Body tips

    OK, so I am just about finished with the metal repair on the cab. I am going to have the cab, doors, fenders, inner fenders, hood and other misc metal stuff sand blasted. I have absolutely no skill, knowledge, experience with body work so I am going to ask some stupid questions:

    There is a paint store (old carquest) that seems to have all the materials, I just worry that they are going to load me up with the most expensive or wrong stuff. So I am hoping to have a little knowledge before venturing down there.

    Assuming clean dry metal

    1. Self-etching primer or epoxy/sealer primer?
    My thoughts was that this stuff would keep stuff from rusting (Florida) while I work on body work (bondo). Any advise as to brand, kind, mix - anything. Assume a complete dumbass when it comes to this stuff.

    2. Bondo?
    I assume this is going to be similar to my welding where 90% of it ends up on the floor! I thinking a skim coat to help with the little dings and dents. Is there a preferred style/type that is durable for truck like activities.

    3. Do I need to re-primer between bondo coats?

    4. When I am done shaping/blocking it all down, do I use a different primer?

    5. Tools - long board, cheese grader, ???? - air vs manual

    6. Education - is there any good books or is it a jump in and figure it out as you go? I sure would hate for the bondo to fall out after I get it painted.

    Thanks for your input.

  • #2
    Probably you'd want to paint it with epoxy pimer, after scuffing it all with 150ish grit sand paper. Be sure to degrease it before the primer, using a prep-sol type cleaner, whatever the paint supply has. As far as brands, we don't know what they have--ppg? axalta? something else? so it's hard to recommend. As long as you use all the same brand stuff, you'll be fine. you can use different brand primer and topcoats, but you have to make sure to use only the same brand hardener/thinner/ reducer/activator with each. I've mostly been using Nason brand, which is the mid range quality from axalta, which used to be dupont. because that's what they have at the paint store here. It works.

    filler, get some medium priced so it works well, but doesn't cost a fortune. The cheap stuff sucks, the expensive stuff is indeed expensive. If you find that what you get doesn't work easily for you, you might move up in price. 50-75 bucks a gallon is reasonable to spend on filler, maybe more if that's what it takes to get some that works well. No primer between coats of filler. use a long board, probably hand powered for now, with 40 grit to knock it down if you put on too much filler, but 80 is preferable. You might also put on a skim coat after you think it's all straight, and use 150 on the long board and see how far off it is, and then keep working on it. The big thing is to not sand too much! if you can feel the edge between metal and filler, you sanded too far and need to fill again. Also, learn to use a bondo spreader (plastic things they sell at the paint store), and put the filler on only as thick as it needs to be, or just a bit thicker, so you don't have it all end up on the floor. It's an acquire skill, and I'm so-so at it, after 40 years of trying.

    When you are done with the filler, you'll want to use a urethane 2k type primer/surfacer, it will sand easily. use a short sanding block for this stage, 180 grit or 240 works well. I usually go through 3 coats of this-prime, sand, prime, sand, prime. If you find low spots (you will) where the sandpaper isn't contacting the primer, you can scuff the area with 80 grit, and add some more filler.

    The bondo won't fall out if you do the metal work well, and read the directions for surface prep and mixing, and don't put it on very thick. 1/8" thick is about the limit, preferably less than that over most of the surface.

    You will need to learn to use your hands to feel how flat the surface is. Some guys use a rag or paper towel between their hand and the surface to help feel the low spots.

    get in there and do it. You can read books and watch videos, but the best way to learn is to hang around a body shop and watch someone who knows what he's doing.
    Last edited by squirrel; July 22, 2020, 04:16 PM.
    oletrux4evr likes this.
    My fabulous web page

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    • #3
      Just gotta trust what they say. All Epoxies are not alike. We just tried to use Eastwoods black epoxy, we did the hood that was off the car, it was fine, did the quarters, trunk lid, rear filler panel, did not get hard. So thats all back on the floor. We have a Promax that has been close by I did not know about, they have this german MIPA paint, we went with their epoxy. I like the 1:1 blends anyway, but he said you can use it for all your filler coats during body work, which seemed good, but then find out you cant sand it for 8 hours. (regular filler primers or surfacers can be sanded in 15 minutes.to see your progress). Tinting primer is something we do between coats, so you can see when you are already breaking thru what you already thought was good, so getting lite gray and dark gray really helps you not need any guide coat .

      Anyway, the differences with Epoxies are basically, can you spray them over old paint, or do they have to go over bare metal. So if you have repaint areas you want to pick one you can use again. Most Epoxies can eventually be mixed with thinner to create the sealer coat, the final coat after your body work is done that keeps anything from bleeding thru to the paint.

      So you gotta find your way. You cannot have an expert painter go in there and set up your gun because it wont look the same. You gotta be ready for trial and error and find your way.

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      • #4
        Assuming clean dry metal

        1. Self-etching primer or epoxy/sealer primer?
        My thoughts was that this stuff would keep stuff from rusting (Florida) while I work on body work (bondo). Any advise as to brand, kind, mix - anything. Assume a complete dumbass when it comes to this stuff.

        Yes to self-etching primer on the bare metal. There are several, different kinds depending on the desired result. My fj40, I shot the self-etching primer then painted it within a few weeks. That is different then the k2000 I used on the Buick. Wear a mask for all of this - it's nasty stuff

        2. Bondo?
        I assume this is going to be similar to my welding where 90% of it ends up on the floor! I thinking a skim coat to help with the little dings and dents. Is there a preferred style/type that is durable for truck like activities.

        Never use bondo brand. again, you have choices, if you're filling a seam, using a metal-based filler, if you're filling, use a skim-coat type filler (and if it's too thick for filler, get your hammer out), once you're to that point (you etched first, did body work over the etch), you will want to spot in the places where you sanded back to metal with etch again. Give a scuff coat then:

        3. Do I need to re-primer between bondo coats?

        no need between filler coats, but at some point you're going to block - then use k2000 or similar high-build primer.

        4. When I am done shaping/blocking it all down, do I use a different primer?

        why? I don't understand the question, when you're done blocking your next step is seal (so you have a uniform color) then paint

        5. Tools - long board, cheese grader, ???? - air vs manual

        I never use my cheese grater - 80 grit is usually enough for rough shaping

        6. Education - is there any good books or is it a jump in and figure it out as you go? I sure would hate for the bondo to fall out after I get it painted.

        cleanliness is everything, it won't fall off if there is nothing between each, successive layer.
        Wear a dust mask - I have one that looks like a neoprene ski mask that has filter inserts... I've found it to be the most comfortable dust mask I have.
        accept that it may not be perfect - but spend the time, I always figure that when I get to the paint portion, I'm 1/2 way to driving the car... the worst paint jobs are rushed ones, it's going to take time and there is no avoiding that....
        mitigate the dust - wives are not happy with a white handprint on their tush.... it is funny, though


        Finally, product.... buy from Summit racing and use their brand this time. I have a local paint supplier, and they can be equal in price to Summit - but it seems like occasionally they decide they need to make a house payment and that I get to make that for them.... they are useful when you want a special color... outside of that? good ones are valuable, bad ones are useless and there is no sign outside which tells you which is which.
        Also, use the big company phone tech... Eastwood (ugh), and Summit both have people who know what they're talking about... eastwood is ugh because they'll try to upsell you... Summit doesn't have that problem because it's all PPG basic stuff.
        Last edited by SuperBuickGuy; July 23, 2020, 11:40 AM.
        oletrux4evr likes this.
        Doing it all wrong since 1966

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        • #5
          and don't be afraid to PM questions... Dan is an excellent resource as is MP&C. I can hum a few bars, but I'm not them
          Doing it all wrong since 1966

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          • #6
            I made a mistake of joining a forum at Southern Polyurethanes. You say self etching primer on that forum and you just insulted everyones manhood and their collective mothers.

            Blasting, definitely epoxy, the etching is done by the blaster. The thing is, if you use one companies epoxy on that, they will just say shoot it right as you get it back. Others say wash it with dawn forever, even if the hard water deposits end up on the car that look like flash rust, the epoxy will take care of that. I dont think you have any cleaner metal than freshly blasted. You want to scratch with 80 grit, well, how long is that piece of paper 80 grit, I do a panel and swear the next one looks like 100 or 120. There is never an answer for that, but you will be wrong if you do follow their incomplete instructions.

            I am not welcome there because I do alot of military painting, airforce, marine, army tripods for drone strikes, so you are told there is only one way to paint, and that is follow manufacturers recommendations. You can have a great blasted surface and have an epoxy fail and they will say they recommend it over an 80 grit scratch coat, so that is why it failed. If God forbid you used etching primer, that was why it failed. So going wherever, you will choose an epoxy and follow those directions. Call those tech lines and see what they recommend over what you have. They call acid primer wash primer and I would trust anything over that stuff. New panels, we actually powdercoat first, no more complete coverage, block it and shoot with the sealer.

            We went 5 years following rules, had mis matched panels, more bondo, but it never cracked. We ended up doing full quarters on both sides when we did the tubs this winter/spring and ended up going to repair rust patches and remember everywhere we had too much z grip. You live and learn if you are lucky, so just commit to something and stick with it and see where you are in 5 years.

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            • #7
              Squirrel covered it well. I'll just add my $0.02. I always use self etching primer on bare metal. I figure there's nothing to lose by promoting adhesion which is what these were invented for. As SBG said, use a good filter mask, not just a dust mask. I use a 3M NIOSH mask and filters (I'll post a pic in a few.)

              Yes, cleanliness is everything. You can simulate a decent booth bu opening the shop windows and covering them with furnace filters and setting up a row of cheap box fans under the big door, opened enough to fit the fans in, then block the rest of the space under the door with cardboard and tape. The fans will eventually get plugged with paint and will have to visit the dumpster but I get mine at Big Lots and it's not a huge loss. I usually get several paint jobs/fan.

              After you're happy with the surface I always apply a sealer cost of epoxy primer (I use PPG DP series but there are many other excellent brands. In DP, the number after the DP indicates the color - for example DP 90 is black). There are differing theories as to whether to pick a sealer color close to the paint color so it's easier to cover or if you want a contrasting color so you can see that you have enough color coat to fully cover the sealer color. I tend to go with a sealer that's close to the color or maybe a tad lighter. Either way, the sealer color will have some effect of the final color which, as a practical matter, won't matter much if you're doing an over all paint job. Thin the epoxy primer with lacquer thinner (the good stuff, not the stuff you use to clean the gun) and it'll spray really well. With DP it gets thinned about 25% or so from my experience but different primers come in different thicknesses so you may need to try it on a non-critical panel before you shoot it on the truck. If you don't have any old body panels lying around you may want to go to Pick n Pull and grab an old hood or something that's easy to detach and use that as your test panel. That way you can try out whatever you're about to do and see if and how it works before you do your good pieces.

              You'll need the instruction sheets that come with your paint products. They will have the OSHA warnings (pay them some heed but for occasional use like we do you can bend them a bit) but they'll also have dilution info (paint to thinner to hardener info, etc.) and wait times. I usually try to get right on the color coats withing 24 hours of the sealer and some (like the DP series) will tell you to scuff the sealer if you wait too long before the color coat. I usually spray the sealer in the evening and come back in the AM to touch up my masking (paint products tend to shrink tape) then spray the color. If you're doing base/clear (which generally gives much better results) I retape following the color coat and before the clear.

              Tack cloths are a good thing! I buy them by the box and use them on everything including woodworking projects. Most people don't use them properly. OPEN them all the way out until they are just one layer of gauze thick then sort of wad them up and turn frequently. The goal is to use as much of the surface as possible. Along that line, there will be times that you'll be hand sanding. Try to always use some sort of block or pad as sanding with your fingers can quickly leave troughs where your fingers are. There are places where you HAVE to use your fingers but aware that you don't want finger grooves.

              If I think of anything else I'll post it.

              GOOD LUCK and have fun. I really enjoy body work in a Zen sort of way. Don't get in a hurry and enjoy the process.

              Dan

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              • #8
                Here's the mask I use. I actually have several that I've accumulated over the years. I bring them in the house when not in use and the carbon filters will outgas over time and reactivate. 3M doesn't tell you that but when you can no longer smell the solvents I figure they're OK to use. I haven't bought one in a while but they were about $35 IIRC - a cheap investment to save your lungs (mine are compromised from spraying w/o a mask when I was young and immortal).

                Click image for larger version

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                The fiber pre-filters (just behind the outer piece of plastic) are cheap and easily changed. If it gets difficult to breathe in you can either try to blow them out or just change them. Also be sure that the exhaust valves are working - otherwise the mask isn't doing anything as your incoming breaths will not go thru the filter (had that happen once on an old mask).

                Dan

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                • #9
                  I keep my mask in the bag it came in, which has a double row zip lock. I also mark on it how many hours I used it for each time I use it, so I know when it's reached the end of it's life (the filters are good for 40(?) hours,

                  I haven't ever used epoxy primer, and I've never had any issues with adhesion or anything. Maybe I'm lucky, maybe it's because I live where the humidity is usually low (except for this time of year). 2k urethane primer is good stuff... and my standards for a finished car may be lower than some other folks. Plus, I'm a cheapskate.

                  Carry on...body work and painting is fun, for a little while.

                  langleylad likes this.
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                  "If it don't go, chrome it!" --Stroker McGurk

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                  • #10
                    This is all great info - thanks for sharing!
                    There's always something new to learn.

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                    • #11
                      Originally posted by squirrel View Post
                      I keep my mask in the bag it came in, which has a double row zip lock.
                      Just toss it in the microwave,
                      Doing it all wrong since 1966

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                      • #12
                        OK, so I will leave the microwave discussion for another group.

                        I do have some follow-up on gear/tools
                        Mask
                        3M 37078 vs 07178. These seem pretty much the same with one exception. The 37078 has an Organic Vapor Cartridge
                        Opinions on which to buy? I am old and most likely won't paint much beyond the truck and probably will only spray the primer and sealer, leaving the final coat to a professional.

                        Long boards
                        Solid or flexible? My truck is not flat or square (has subtle curves on a lot of the panels).
                        Dura block sells a long board/block but it doesn't have handles so I am not sure if it will work as well

                        Sanding blocks
                        I have a sanding block (Holy Terror 5 x 2 1/2) with holes on one side and solid on the other. I noticed that Dura Block sells an assortment of these things (including a long board)

                        Spray guns
                        I have a cheapie Harbor Freight gun that I was thinking would be a throw-away when done with the primer.

                        I have a home made water separator (bunch of copper tubing on the wall). Do I need a better water separator at the gun for primer?

                        I am making a list of tools/supplies so that when I get closer to being ready, I will have what I need to proceed quickly.

                        Again, thank you all for your input.

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                        • #13
                          I dont think there is much difference with the respirators, one might be completely disposable and the other with filters that can change. I think we paid 25 or so on amazon for the one time 3M deal since the straps slack and you might get one change before wanting to dump it anyway.

                          I like the durablock different length blocks., I did just get a durablock flat line sander from a guy supposedly in Colorado for like 76 on ebay. brand new, it was here in less than 2 days. Really nice flat line air sander to do the heavy stuff. 2 3/4 by about 16 long you can use the sticky rolls on.

                          I have bought quite a few Neiko spray guns on amazon as well, usually about 30 - 40.00 depending on tips. Far nicer than the harbor freight purple guns.. If you are going base clear you are going to want closer to a 1.4, for sealer as well,,the 1,8 harbor freight size is good for the build type primers, if you are going with slicksand or featherlight primer with filler (just used it on the camaro this time, saved alot of time with the tiny imperfections) the 2.5 worked nicely. it usually costs more to just find different air caps than another gun..

                          Water separator is dependent on your compressor. If you are not on constantly or on for 10 minutes, off for 2 deal you should be ok, If its running alot and you are getting hot air then definitely should do some more. Motorguard has some of the colored desiccant you can put on your gun if you are borderline. I prefer one on the wall and one at the gun. At least you can see what those are doing. I guess I just spent another 200.00 for you, but eventually you get there if you end up sanding and respraying more paint.
                          oletrux4evr likes this.

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                          • #14

                            I do have some follow-up on gear/tools
                            Mask
                            3M 37078 vs 07178. These seem pretty much the same with one exception. The 37078 has an Organic Vapor Cartridge
                            Opinions on which to buy? I am old and most likely won't paint much beyond the truck and probably will only spray the primer and sealer, leaving the final coat to a professional.
                            buy the best you can, yes to the Organic vapor, but there's also a dust cover for the cartridge that really isn't necessary - by the time dust would plug up the cannister, you should have already thrown the cartridges away.

                            Long boards
                            Solid or flexible? My truck is not flat or square (has subtle curves on a lot of the panels).
                            Dura block sells a long board/block but it doesn't have handles so I am not sure if it will work as well

                            there are various hardnesses. it really, really depends on your preference. I don't like hard boards because they sand radii flat - but I use mine occasionally. My most used 'block' is the soft pad that is the size of most dishwashing sponges. About preference, I used to build stainless, kitchen equipment - there is only hard/flat available for that - so I've learned how to do radius with them.... thus when I do any kind of fill coat or whatever, I use pretty aggressive methods then jump to soft/220 paper to refine


                            Sanding blocks
                            I have a sanding block (Holy Terror 5 x 2 1/2) with holes on one side and solid on the other. I noticed that Dura Block sells an assortment of these things (including a long board)

                            durablock was first, but not necessarily the best anymore. people seem to like the holes because it allows them to cut flat surfaces faster (because all those holes really do is create voids and those voids mean you're putting more pressure on the surface because you have less, sanding, surface area.

                            use what is comfortable with you. if you break rocks in a sandbox, get a pad that will sand all the primer off the radius equally when pressing on the ends of the block - if you're Michelangelo and you can do fine detail with a chisel, then the hardest block will make it go faster.

                            Spray guns
                            I have a cheapie Harbor Freight gun that I was thinking would be a throw-away when done with the primer.

                            been recommending this for years - that said, I usually clean the inner surfaces so I only have to use one gun for all the primering....

                            I have a home made water separator (bunch of copper tubing on the wall). Do I need a better water separator at the gun for primer?

                            water (and oil) is your enemy - the finest droplet can utterly ruin a paint job. I use a separator on the compressor, two separators then a drier (uses desiccant) then the hose, then a reusable seperator on the gun. Where I live, humidity is usually below 40% - and I still get water all the way to the gun.... the copper radiator is good, but you will want better for painting. That said, I don't run air through the seperator when I'm not painting or using my plasma torch



                            Doing it all wrong since 1966

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                            • #15
                              I have plumbing running around the top of the walls of my shop, with several drops, each drop has a drain below the fitting that I plug an air hose into. When I am painting, I use the last drop, so the air has a chance to cool and the water condense out, before it gets there. The air path is over 100 feet long, plus the 50' hose that connects to the fixed plumbing. It works.

                              Be creative with sanding blocks/long boards. I end up using all kinds of things...paint sticks, radiator hoses, etc for different conditions. But mostly I use a solid long board, and a mostly solid sanding block, for the flatter surfaces.

                              My fabulous web page

                              "If it don't go, chrome it!" --Stroker McGurk

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