Update on etching primer for the new frame. NAPA had it on the shelf. $8.99 per can. Bought the three cans they had. Ran out. Went to PEP Boys. Same brand and all that...$4.99 a can..It is Duplicolor brand name. It worked great for us. I had to work hard to get the runs in it. Thanks for the advice from all of you.
Sorry, guy, but I think you're thinking of a different product. Vinyl etching wash, or primer, as it's sometimes called, is what you're describing. I use Dupont Vari-Prime, which is a true primer that uses an acid for it's etching abilities. Different product, similar name, though. I have been painting directly over it, and my stuff has been around for MANY years. I only do this when the part is clean, not needing any additional filling/smoothing/sanding. Just a prime coat and paint. Do it a lot on steel wheels, and such.
Mark is right. There are basically 2 kinds of etch primer. Vinyl wash primer: very little film build (fill) and it is slightly more aggressive, acid wise, because it has only a vinyl resin as the film. You can usually see thru it. It is translucent (very thin) and care should be taken not to apply heavy thick coats. THIS etch primer should be coated with either a primer sealer or primer surfacer (filling primer) before a topcoat/paint is applied usually with a wet on wet system after the etch primer has flashed for 1/2 to 2 hours. In industrial/fleet applications this is usually applied to sandblasted steel or aluminum then sealed with a primer sealer and painted. For restorations it is usually applied to bare sandblasted steel or aluminum and primed with a filler primer so it can be blocked sanded or leveled before painting. This type of etch primer should not be used over body filler. Some examples---PPG 1791 etch primer or 171-172 etch primer---Sikkens wash primer CR. Mild etching primer: this has some build or fill but is less agressive acidwise because of the solids or filler in the primer. This can be painted over with some single stage paints without other primers (check the tech info for the brand). It is usually applied to sandblasted steel or aluminum and can be coated with primer surfacer (filling primer) or sealer wet on wet after about 30 minutes up to 72 hours (or longer) with some brands. This type of etch primer is OK over body filler (not heavy wet coats). Some examples--Sikkens Wash primer EM---Sherwin Williams GBP---Dupont Variprime Most companies use the same activator/reducer for both etch primers, which is a solvent blend with about 5% phosphoric acid. The phosphoric acid in the reducer is the "etch" and converts iron oxide to iron phosphate. This my preferred primer for sand or media blasted panels. I usually follow it with some 2K urethane high build primer surfacer (wet on wet). I've used this mild etch on bare engine blocks followed by a good quality single stage urethane color with excellent long lasting results and lots of steel or aluminum wheels like Mark does. I'm not sure where the spray can/aerosol etch primers fall in here, but I'm guessing more like a thinner version of the milder etch primer. I like them for small parts or touch up on welds, etc. Automotive panels new from the factory have a phosphate coating on the bare steel. When you sandblast or sand the metal on a car you usually remove all or some of this coating. You can replace this factory corrosion protection (phosphating) with a 2 part metal prep acid wash which is messy and time consuming. Although not quite as good, using an etch primer on old sandblasted or sanded steel panels is the closest you can get to replacing the phosphate coating. If you use the metal prep and converting system to phosphate coat panels, you should NOT use an etch primer. It will probably fail and peel off. Several automotive refinish companies require using an etch primer when repairing new car finishes in order for the paint and repair to be warrantied at the bodyshop. Polyester based primers (featherfill-morton eliminator-etc) usually cannot be applied over etch primers, because the acid will slow down the catalyst (MEKP) in the polyester primer and cause the cure to be longer. I did read in the new Evercoat Easy Sand tech sheet, for that brand of polyester primer surfacer, it can be applied over etch primer but it extends the cure time of the primer. You should not use epoxy primers over self etching primers as the acid does affect the activator of the epoxy and can change it chemically so the epoxy may not cure correctly or at all. Epoxy primers DO NOT etch or convert rust/iron oxide. AS always, read the tech info. Most of these companies have good information available on the web or at their local distributor's store, and you can always email or 1-800 a question to their tech dept. As with all good priming systems (epoxy-etch-urethane-polyester-etc) , if you read the tech info,it always says: "The bare steel should be clean of grease, oil, and dirt and free from rust." overspray
pcl also recommends their etch under their polyprimer. some brands are just different. i could have sworn that if ppg dp is used under the recommend film thickness that etch primer should be used. dplf. like they didnt say it at first then changed the tech sheet.
According to the TDS: If DPLF epoxy is applied at less than 1.2 to 1.5 mills, the metal must be treated with metal conditioner or they reccommend their DX 1791 etch primer. It shows that it is OK to put DPLF over the etch primer, but no time frame. https://buyat.ppg.com/refinishProdu...?BrandID=5d7b4ed7-f83a-4469-b68c-04551702a5df Also for those of you buying Brookville bodies, they are cold rolled steel with NO phosphate coating. I talked to the shop manager about their bodies that are primed, and he said they use the cheapest lacquer primer they can buy for a transport coating. That's why a lot of their customers order them bare steel so they can clean the metal and use an etch primer or other good system on the new bodies, so they don't have to deal with removing the lacquer primer which is not compatible under some of the new paint systems. overspray
Well then go to "school" and read about the real good stuff. New School? Maybe, but here is where a lot of our American Refinish Technology came from. The Europeans have been ahead of us for quite a while. That's why most of our American Automotive paint companies alligned themselves with european companies and their products back in the 1980's. That's when Base coat/Clear coat started on OEM vehicles. American Technology struggled with BC/CC until European paint technology was accepted. Before you can have a good topcoat finish with base coat/clear coat, you have to have a very good undercoat/primer system and the European technology was leading the way. Etch primer is still a part of most Paint companies warranty system for collision repairing OEM finishes. Lacquer primer under alkyd enamel or lacquer topcoats is "Old School". http://www.glasurit.com/Products/ Here's some good systems. Glasurit has very good products. They have very good epoxy primers, etch primers and high build. You will see that etch primers are reccommended on large bare metal areas for best corrosion protection in the restoration systems. http://www.glasurit.com/COLOR/ClassicCarColors/ClassicCarColors.html Here's the Sikkens wash primer and color build urethane primer on a Porsche 911 restoration. This is a very good system also. http://wilsonkirksrodshop.com/PorschePage.html
i've used the nappa brand to protect bare metal spots while working on them. never had a problem. also the duplicolor self etch has been really good. put real primer over both with no problems, and that was at least a year ago. the difference is that self etch hence it's name etches and bonds to bare metal, regular primers aren't made for bare metal. other then epoxy of course.
Im using SEM on my truck, here's a few pic of my front fender after we laid the primer down. I'm spraying high build over the etch primer to fill in where the paint cracked and pitted.
go to school? been there. learned it, shot it. when do u have large bare metal spots on a resto? a proper resto would get atleast a skim. it has its place, but i will use epoxy more then i will etch. im not into sikkens, so i dont pay attetion to there system. to euro for me. same with glasurit. etch is faster then epoxy. it has its place in bodyshops. there are different kinds of etch. some are closer to dtm primers then just a transparent piss coat etch. nitro laq over laq primer is old school. with lead as your filler,or the first mud mixed as a powder, but hey whatever. just cuz i denfined old school as the past 20 years, doesnt mean its the oldest. alot of the etch primers ive used rust if u leave them uncovered without a coat of epoxy or 2k primer over it. dont base all etch primers on like 2 good ones that act more like other shit.
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