My car has been painted in etching primer. I understand this was due to the fact that etching primer does a better job at sealing out moisture than regular primer such as DP-90. I was also told it does a better job at "biting" into bare metal. I have heard that precautions must be taken if I am to paint over this stuff. Can someone school me on etching primer? Truths/myths/what needs to be done to get ready for paint/etc..... Thanks in advance...
You will have to prime over etching primer. The etching primer (E/P) is a phosphating agent that actually 'bites' in the metal, a coat of regular primer will then adhere to the E/P. Block sand as usual. Re-prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand. Prime. Block sand and then paint...
etch primer is mostly used as a bond between the bare steel and a primer, if you do prime it with a filler primer, you will need to scuff the etch prime. I would not paint over the etch.Etch prime will not seal as good as a sealer primer(2K, epoxy,urathane) Jack
Ok, so I don't need to take it all off, just make sure I use a good sealer primer over it? How about filler adhesion?
You are not supposed to put filler over etching primer. Either take those areas down to bare metal, or use a primer that is compatible with fillers, ie: epoxy primer. I have seen filler applied over etching primer and it looled ok, but the directions say not to as the acids in the primer that cause the etching in the first place will eat at the filler. Also, etching primer WILL NOT seal the metal. You should use a sealer/primer over the metal etching primer before exposure to moisture, or you may have to take it down to bare metal again.
Let me toss my hat into the ring. The best paint-jobs are done when you 1)strip it all the way to bare metal 2)do ALL metal work 3)Do your bondo - filler work 4)etch prime the whole car 5)Filler prime the car 6)complete the finishing body work with any necessary filler. NOT bondo, but stuff called icing - it's much softer and is used sparingly - this is where the blocksand-primer-block-prime-block aforementioned comes in 7)seal prime the car and finish sand-prime-sand etc. to get rid of sanding marks with the high density grits 8)start painting process (paint systems vary slightly according to paint manufacture and desired paint effect - like candies and such) 9)clear 10)wet-sand 11)buff/wax Starting with a car that is already in etching primer will work just fine if the body work is minimal. But if you have areas that need attention you are going to have to re-etch the areas or you may (eventually) run into some kind of inadequate paint adhesion or other failure. I'm no expert though - I've just seen the process a hunnert(TM) times or so. I am the shop slave - I do the dirty work (aka block sanding and other shit work)...but I am pretty sure this is how it works. A lot of folks get put-off by the body work side of the hobby, but it really isn't all that bad of a job. My dad has a better "feel" for it than I do (when it comes to finding flaws that is) but I have learned a ton working with him and my brother complimented me on the good bodywork on the last project so I feel pretty good about it now. Someday I will be able to go from start to finish without any help at all......that's the goal anyways, right? A year ago primer was primer and paint was paint - they all looked like the same thing to me. I know better now. ...if I could go off on a tangent here..... I have come to the conclusion that I will ALWAYS choose to go the shiny paint route vs. the primered rod from now on. The thing about doing a primered rod is that you have to spend a ton of hours just to get the body work all finished (weeks on top of weeks of sanding your fingers to a nub) then you just quit on the final prime... ...and if you tried to sell that car (in primer) folks look at it like a project - in fact they wont trust your body work and will probably just sand it back down to metal....I know, I know - that's their problem. But if you are the guy who just spent months getting the fucking car all straight and some potential buyer looks at it as a project - you are not going to get paid what you are worth (all of those weeks go right down the drain). For that last little bit of extra work - a couple more hours in the paint booth - your car could be painted. And a painted car pulls a lot more dough on the market. (here's some bad news for my Buick buddies) I just sold my Buick this week for 5k. It was in primer. I loved the fucking thing and I loved driving it around. I really loved my primered paint too, it was cool. But when I went to sell it I started kicking myself in the ass because I could have doubled my money for just a few extra hours of work......fucking idiot...I had no intentions of ever selling it when I was building it. Hell I was falling in love with the damn thing - I was NEVER going to sell it (at least that's what I thought). Then life smacks you in the mouth one day and something's gotta go........the '34 will be shiny - eventually.
My neighbor visits body/paint shops all the time. I could swear he did a 3-step of primer. 1)gray etching primer that bites the bare metal 2)puke-colored sealing primer (I think it was) 3)filler primer to get any imperfections out. Then paint on top. Please correct me if any of these layers are incompatible with the previous layer, and, if they are out of order. This is just what I seem to have remembered. Also-- this I know: If you lay one primer, and then you break through to what's underneath, then you must shoot again if the next planned coat is incompatible with what you just exposed. Each time of course, you are sanding, roughing up. I believe this is what the above said/paint/sand/paint/sand/paint/ad naseum comment was referring to. It is a tedious process to make a perfect paint job, if you are using shiny paint. Ever see the cars at a car show that look wavy and ripply as the ocean in the sun, or in lights at night? They didn't think it necessary to do all this painstaking work...
Oh yeah, this stuff can KILL YOU if you aren't wearing the proper OSHA-approved respirator for it. Some of these things have cyanates (like cyanide) in them.
Actually severl mistakes told in this thread. Look at Oversprays Tech pieces in the TechoMatic. Bondo and Spraying a TrackT
ok, i'm going to throw my 2 cents in, etch primer was used to provide adhesion between the top coat and the metal, without sanding, If you sand a piece of metal a good primer will have a mechanical adhesion. if you had say a car trailer made out of new steel, you would have to either sand the new metal or etch prime it, to get paint to stick to it. A trailer is to big to sand, etch primer is faster. I have been in the body paint business for 30 years, I no longer use any etch primer because of the acid used to etch the metal, paint dosen't like it. It soaks moisture, I epoxy prime everything, one thing for sure, you never, I mean never put epoxy primer over etch. primer, It will peel off. ppg dp-40 is epoxy and is made to be applied directly to metal. This is what every body was using a few years back but the product changed because of goverment reg, on the use of zinc phospate. and the primer is not as good any more, most paint companys have a primer that they call DTM, which is [direct to metal]. They guarantee the paint for lifetime if you use there product through out. from bare metal on up. this is what I would use, or epoxy 1st and them a filler primer like 2k urethane primer, then paint, obviously alot of sanding in between. one thing about the epoxy, it has no uv blockers so although it goes on super smooth and the black is real cool looking. the sun will make it chaulk up. it can also go over unsanded aluminum and is super durable. I worked on a aluminum bus and sprayed 5 gallons on the new unsanded aluminum panels inside and out, after it dryed you could not scrap it off, you can also put bondo over it, just scuff it up a little, hope this helps, I would sand the etch off, it soaks moisture anyway, and if the car has been sitting awhile it could have rust starting underneath, besides it sands off easy.
Really? The way I have it explained is based on what I can remember from just being around the shop, but I really tried to pay attention. We use the Dupont systems mostly, and occasionally the PPG. I knew I should have called dad to be sure. He is a GM certified painter - painted for over 20 years professionally. ....now, what'd I do wrong?.........
I hate to say it, and I'll get alot of flack on it but you said the word I didn't want to here, DUPONT, dupont never had and to my knowledge has an epoxy worth a damn. so they push there variprime, it's all they got for bare metal. there epoxy crolar or what ever the hell they call it is junk, besides I hate jeff gordon and don't like paying for the hood on his car. all I can say is read the label it will tell the you what to do. which ever peoduct you use, Ive painted hundreds of cars, I only want to paint a car once, and don't want any problems when there done. 99% of paint problems are the painter or the way the product was mixed or used or misused.
G Jammer---I agree, J Gordon is a phagg. Dupont, however, does have a pretty good product line. I think Veriprime is a good product. Dupont also has Prime N Seal 2640 that is vary versitile. It can be sprayed on bare metal or over body filler or body filler can be applied over it. It is not an etching primer but Dupont also has Kwik Prep 244s metal conditioner that can be wiped on first if you don't want to use Variprime. If you are a novice at paint and body work, go to your local paint jobber and get some product information data. There are many good paint companies today and 'all' will work with you to give you the advice to make their product line work for you.
I do remember that about the etching primer, if the car wasn't painted quickly, little rust spots started to show.
Dad hated Dupont, but it was what the dealership used and he had no choice (shop economics 101 - buy the cheapest shit you can to boost profit). He has since learned how to deal with it, and can use it to get good results. He cut his teeth on PPG and always favors it. He has only used HOK a few times - upon request. ...but I still want to know where in my reply I am wrong, not because I want to prove anything, just that I want to learn. So can someone tell me where I went wrong? I thought I had a pretty good grasp of things.....
I looked at the Tech-O.....I still don't see where I was wrong. Overspray? Tman? anyone....seriously, if I am going to learn from my mistakes, I am going to need to know what they are.
The Bondo 101 post is a lot of reading. I went to a swap meet this weekend and just got back, otherwise I would have added to the thread. Every one was on the right track, but some specifics pertinent to the information given were left out. Doing your own research is the best way. Then ask questions to clear up things you don't understand about the information you recieve. Otto- If your car is rusting under the primer and you want to redo it "right", then you should remove the primer-probably a panel at a time-then re-etchprime with a specific primer system in mind. There are 2 basic etch primers- VINYL WASH primer-has more etching capability but no film thickness or build. It needs to be topcoated with a fill primer or sealer and then paint. This type of etch primer should NOT be put over Bondo. It is for bare metal only. MILD ETCH PRIMER WITH SOLIDS-has a milder etch and some fill. It CAN be applied over Bondo. Vari-prime (DUPONT),Wash primer EM (SIKKENS AKSO/NOBEL) are a couple of names that come to mind. This can also be topcoated with a filler primer or primer sealer or directly with paint (industrial application.) You have to check and see what system/brand you are going to use and then get the technical info on the application requirements and read and follow the manufacturers instructions. DO NOT use metal prep before applying etch primer-it needs just a microscopic amount of oxidation to bond with. The phosphoric acid in the etch primer is usually less than 1% but that bonds with Iron oxide (rust) to form Iron phosphate which is the etching/phosphatiing process. Removing all the rust with metal prep/conditioner (phosphoric acid) will leave nothing for the primer to bond to and can lead to peeling. These systems usually go as follows: Vinyl wash primer-1 medium wet coat (.5 mil) over clean, dry, sanded/sandblasted bare metal. You can see through this coat-its very transparent. This followed-probably within 30 minutes (wet on wet-no sanding) by a good catalyzed 2 part filler primer for filling and sanding (5-20 mils). Or in straight refinish (trailers/industrial) applications-vinyl wash primer followed wet on wet by a non-sanding primer sealer(1.5-3 mils)-followed by paint. With the milder etch primer you prepare the metal the same-do your bondo work then clean and apply the milder etchprimer (1-2 mils) followed wet on wet/no sanding (probably within 30 minutes) by a good catalyzed 2 part filler primer for sanding and blocking. For project cars I usually rough out the metal-do my filler work on the large areas then use the mild etch primer followed by 2 part filler primer. Then for smaller areas I can use the spot filler/ catalyzed glazing putty over the sanded filler primer to smooth out small imperfections. I will probably reprime areas that need more fill and block sanding-then on to paint. If it is going to sit for as while, I prep the steel-then etch prime (either one) followed by good 2 part filler primer. Then when I'm ready for bondo work, I just hit the repair area with a grinder to bare metal and do my bondo work followed by the filler primer. Epoxy primers DO NOT etch the metal. They bond by mechanical adhesion. There are many different epoxies for specific applications. You need to reasearch what will do the job for your intended purpose for which ever primer/paint system you are going to use. The acid in etching primers can cause the epoxy primer catalyst/hardner to change chemically and not cure or possibly fail/peel. The acid in etch primers slows down the catalytic reaction of the hardner in Bondo/body filler (polyester resin-catalyst MEK peroxide). If you put bondo over etch primer and there is still a minute amount of residual acid-you could have a failure/loss of adhesion etc. The amount of acid is very minimal in these primers. It is mixed with a solvent to reduce/thin the primer. If the etch primer is not fully dry and cured there COULD BE be residual acid/solvent in the primer film which could cause the reactions described above. Also-PLEASE be careful about posting "I used this and it didn't work for crap!" There are and have been some "CRAP" products out there. I probably have a lot more experience in "screwing up" paint and body work than most. Early on I learned that finding answers and good information for solving problems and correcting mistakes saved me a lot of time and money. If the stuff is "CRAP" find out why-or is it possibly an application/technical error. If learning from mistakes is good-then I must be KING. That's why I'm heavy into this technical stuff. I've asked a lot of the questions you all have and I tried to find most of the answers. I'm still working on it- it's a never ending process-and I don't know everything. overspray
Broman, I was referring to Acid Etch over Sandblasted parts. My PPG rep passed along the information that the acids in the acid etch can pool in the "pores" left by blasting and cause problems later on. Thats why we Use the BlackScotchbrite pisks after blasting to prep the metal.
OK. I was trying to be terse in my reply. A long winded response would get glassed over pretty quick. I tried to put it into a 10 step and your ready kind of connotation, but in retrospect that's not possible in a good paint job. It's more like a 100 step program......With variables. Now I am going to re-read Oversprays reply, I skimmed it too quickly......
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