What are your recommendations for restoration paint finishes for a Model A?
I have been using single stage polyurethane over epoxy primer on the body, fenders & aprons, POR-15 black on the frame & brake drums, powder coat on the wheels, Krylon primer & black paint on components & what the dealers sell for Engine Green.
I avoid using clear coat paint on the body because it complicates DIY touchup of chips & scratches.
This is a loaded question for sure...... Are you wanting answers to what is the easiest/cheapest? Are you wanting it to look aesthetically correct?? Are you asking what the latest products are???
I made a comment the other day to the effect that whatever you knew and did 5 years ago in the paint world is outdated technology, ...with some products not even available for purchase now. PPG's Concept (DCC line) is pretty much one of those.
Just a few short years ago, the wisdom was to spray the bare metal with a catalyzed Epoxy primer, then do the Filler work over the Epoxy, followed by using Hi-build Primers (-Featherfill, Slick-sand, etc.) then a Urethane surfacer followed by the Topcoat. In reality, all that has changed. Now the recommendations by the leading paint manufacturers is use any body fillers listed as DTM (-Direct To Metal) since much of the Epoxy would be sanded away as the fillers were leveled using the surrounding metal as the datum gauge. FWIW, the old Slick-Sand, Featherfill, etc. were not really DTM approved which is why there was a push for using Epoxy.
So now we prefer to use an Evercoat product that is called EverGlass because it is very flexible and acts much like fiberglass being waterproof and chip resistant. Although I don't necessarily recommend using it this thick, the manufacturer will allow it to be ¼" thick ...and survive. ( Try that with body fillers we all used a decade or so ago!! ) Once the filler work is completed, you are ready for a Primer/Surfacer that takes the place of filler skim coats of Rage Gold or Platinum Plus.
Our preferred High-Build Primer is EverCoat's Optex 4:1, ...and I feel this is a breakthrough for the home hobbyist restorer for several reasons. To begin with, it is DTM which saves in time & materials fo having to apply Epoxy. Secondly, it is waterproof which is a plus for those who watersand their surfaces. Also, being water proof is extremely nice for those who take long periods of time to finish their bodywork. Now a sheetmetal piece can be partially completed and then set for months/years without worry of the primer drawing moisture and setting up rust under the substrates as long as it is fully coated with Optex. Another thing that is a huge plus for Optex is that this product dries in a pinkish color. Once dried, as soon as the 'shell' of the primer has been sanded thru, the primer turns from pink to gray. For older, tired eyes, this is a huge help in ensuring you know where you have sanded, -and where you haven't. The final benefit which we like (-and something I feel is great for the home restorer) is we often roll it on instead of spraying it. We use a 4" wide foam roller to apply the freshly mixed Optex and it rolls on just like Latex paint from the big box store. Do as big, -or as small of an area as you like. And, what this means for the home restorer is they can mix smaller quantities yet actually apply more of the product because you are not losing a portion of the product in overspray during the application process. Cleanup is a piece of cake too since you throw the foam roller and the plastic paint tray away. (-once dried it is no longer considered hazardous waste) Also, the time savings of not having to clean a spray gun, nor spending the money on a dedicated primer gun with a 1.8 or 2.0 tip is a plus. Theoretically, you can now prime your pieces in the driveway with all your neighbor's kids watching without worrying about the popo being called. I have linked some literature below for those who want to study this a tad more.
The final thing I would recommend is using US Chemical's Icing putty at two different stages. This product is much akin to the old Nitro-stan putty that we used 50 years ago except the Icing has longevity built into it. While the Icing is not DTM so care must be used when applying it over the EverGlass, it is really good at filling 36 grit and 80 grit sand-scratches when the EverGlass as been sanded. With this product used to fill the deep sand-scratches, there is less chance of trapped air when the Optex is applied. Just apply a thin coating over the EverGlass and sand with 120 grit and you are ready for the Optex. Then, when you are nearing the 400-600 grit blocksanding phase, if you have any imperfections to correct, the Icing putty is perfect for this. Since it will be sanded, it can be topcoated with a 2K urethane paint -or you can add some Optex ove top to seal it in. The reason why the Icing can do this is that it is also a Polyester product that does not absorb water.
Probably the only other thing that we use that is worth speaking about is our production paper (a/k/a sandpaper.). We have pretty much phased out stickyback sandpaper on a roll. Instead, we are using a 'screen' product that looks like the stuff you work drywall mud with. The product we use is called
AutoNet, and comes in grits from 80 grit all the way to 600 grit. Click on the link to read more about that stuff if you are interested.
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Ohh, and for those who are frustrated that PPG dropped the Concept paint line, there are two options that we have found. One is PPG's product called Evolution that is in their DelFleet line. This is the product that most closely replaces the Concept. Another option is a paint called Imron. While many may remember when DuPont revolutionized the paint world when they invented the aircraft paint called Imron, -well that paint was phased out however when Axalta purchased DuPont, they brought out that line again formulated to compete against the properties of Concept. It has a higher solids content over what we are finding in the Evolution (-or Essential) lines, and so far we have been able to a very, very close to exact match when the Model-A Paint & Refinish Guide chips are scanned.
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