I'll be getting my fenders and trunk/hood lids back from the media blaster this week, and I have questions on what to do first re getting them prepped for paint correctly. I've been told to hit them with etching primer first, then again I've been told to use an epoxy primer first. Which is correct? Can I use body filler over the top of the primer, or should the panels be smoothed first and then primed? I've heard that you cannot use body filler on top of etching primer, but you can over epoxy primers. Can someone out there set me straight? I'd like to spend the winter getting the entire body smooth and straight and ready for paint in the spring, and I sure would like to know I'm doing it right. I know I can screw it up once or twice and still spend a ton less than I would if I took the car to a pro, but I'd love to get it right the first time. Thanks for the help.
I would recomend the epoxy one light coat. to keep them from developping surface rust while storeing or working on them. After the primer has dried (at least over night) I would then lightly block sand to find any areas to be fixed try to get it as straight as your abilities will allow. then you can use the filler of your choise. Epoxy is very compatible with plastic fillers.
one light coat might not cut it. each company has a spec on how much film mil thickness needs to be applied. ppg i think is 1.5 mils. so one wet coat. or 2. if not u need an etch then epoxy from ppg.
Hey, If your intent is to primer these parts the day they return from the media blaster, as you should, than I'g go with a top brand epoxy primer for now. You've been told correctly, that some etching primers ARE NOT compatable with plastic fillers over them. The acids in the primer are reactive with the fillers' hardner and will lift and peel the plastic. I'm not a big plastic filler over primer fan, but it would be far worse to leave these panels unprotected until you repair them, by not primering them. I'd suggest two full wet coats of primer over the freshly blasted panels. S****ey Devils C.C. "Meanwhile, back aboard The Tainted Pork"
Keep your bare hands off the panels, handle them with rubber gloves. If you are going to apply filler over epoxy use 80 grit to scuff up the epoxy. If you go filler over bare steel, sand it with 40 grit.
you need to ask the guy who sells you the paint. you'll end up with 5 answers for 5 different kinds of paint. seems like everytime I go buy paint the stuff I bought last time is no longer available. bondo? I go into all my projects thinking I can do this without bondo. of course it rarely happens, but it would never happen if I didn't go in trying to not use any.
I usually don't disagree with pimpin paint...but I use filler over epoxy a lot. BUT, I use House of Kolor epoxy, which is different from most major brands. Etch...no filler over it, or under it. You need to put a urethane primer surfacer on top of it, too. I believe most epoxies are NOT recommended for use with etch primer..again, check your tech sheets carefully! Epoxy...maybe, you really need to get tech sheets for whichever product you plan on using....different epoxies, from different companies, have different characteristics. Some are adhesion coats, others are sealers, few are surfacers, as well....there IS a difference! Be sure to sand the newly blasted panels before priming. you need to remove any stray bits of media that may be caught in the metal's pores befpore priming. A light "go-over' with 80 grit is good enough. All the other posters' advice is good, handle with care.
i own my own resto shop ive painted so much stuff its retarted .. get your panels back if its not humid dont worry about rust run 80 grip over the parts on a da this will also show you your dents and flaws do your filler work i dont know how good you are at it but i like to have it super close so i dont have to waste alot of primer $$$ i have the filler finshed in 150 grit when your ready to prime it use a acid etch sealer then prime it remeber when blocken that if you break thru to bare steel you will have to reseal that spot before your next coat of primer ..they offer a direct to metal primer but i dont trust it i dont use epoxy to me its alwas kida gummy plus they took all the good stuff out of it and they did away with dp so i dont use it ....ill be glad to help you any time..brett
We've got one place here that you DO NOT ask the guy selling the paint. He has no clue, he just sells the paint... Regardless of what anyone says read the sheet... It's North Carolina, of course it's humid...
Self etch primers are lac. primers with acid in them to bite into the steel but are very porse and water will go right through them like they weren't blasted at all. Use epoxy cover all bare metal, once dry, sand, fill, paint, do anything over it you want. NEVER USE PLASTIC OVER SELF ETCH. I was Factory rep. for BASF for 30 years so read your tech sheets, a few minutes of reading can save you a week of redoing a job. Don
some companies epoxies recommend etch if the mil thickness is not enuff, say when using a epoxy as sealer over baremetal.
Does anyone else find this completely wrong? I know that certain epoxies are compatible with certain etches, but an acid etch over filler? What?!?!?!???!!?? Mark (Chopolds) beat me to it. I too use HOK Epoxy exclusively just as he does and for the exact same reasons.
Dont leave any flaws cuz ones you can find will stick out like a sore thumb and the ones you cant will be there too
been doing it for 20 years and never had a come back .and i got tons of **** you can look at .....its like ford / chevy every one has there own way of doing **** so do what the **** ya want im done helpen any one ..im not here to fight .
You might find this link interesting, you might have to scroll down a bit to find the article: http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=2331682&page=0&fpart=1&vc=1
Not trying to start a fight there tough guy. Acid over a filler? Am I reading this wrong, understanding it wrong, or what? A special product we don't know about? I'm being serious, please enlighten.
Bill--you and Mark use one of the better and very versatile epoxy primers (HOK) that is on the refinish market today. Good film build, good sandability, good holdout. Now read this little text I posted on the DIFFERENT TYPES of etch primers and where they fit in as a priming system. The mild etch primer is OK over filler. The BASF rep should remember that Glasurit had (maybe still do) a great warranty reccommended 2 part system using either of ther etch primers followed by their hi-build urethane. There are basically 2 kinds of etch primer. VINYL WASH SELF ETCHING 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 SELF 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
Ok so I had it backwards? The milder etches are OK over filler but none are OK over epoxy? I thought that any acid would lift the edges of the filler? I've honestly never used etch primers in great abundance, so I really don't know all of the specs on them. For what I do, I find it easiest and best to just stick with the HOK. As far as the phosphate coating, we talked before about Picklex. I remember you were saying to be careful about using it with the HOK. Well Mark and I both have had good results paring the 2 and it acts as a metal wash and replaces the phosphate coating. I'm blasting my own car panel by panel, maybe I'll try some mild etch on it instead. We'll see.
Acid is NOT the issue with lifting edges. It's the solvents that lift edges where the material is thin and the solvent can penetrate the film of the primer, or paint, or even filler edge. ANY primer or solvent based coating can lift an edge if applied to heavy. Etch primers are usually reduced 1 to 1 with the reducer which is 5%; acid. That means the total mixed primer is only 2 1/2% acid. The vinyl wash primers have almost no filler material so the acid is more aggressive simply because by volume there is slightly more acid to filler material ratio. These primers only need to be applied in very thin coats and the film is translucent. They also need to be primed or sealed before paint. I would not put epoxy wet on wet over etch primer, especially vinyl wash primer. I have put epoxy over mild etch primer after it was dry and scuffed, and I was pretty confident there was no significant acid left to react with the epoxy hardner. Acid doesn't linger forever because it is converting with another material and changing chemically so it's not an acid anymore. Even straight metal prep is diluted down to 10 or 15 % acid. Also when you use picklex or another acid prep, it is usually rinsed with water and diluted to the max as it rinses off. Usually, there is no acid left after rinsing, or in the case of spraying etch primer on metal, it converts with the iron oxide or in the mild etch, also with the filler part (chromate for instance)of the primer so it (the acid)is usually gone (converted or diluted or rinsed away) after the film dries. That's why etch primers have a "pot life". After mixing, the acid starts to convert with the components of the primer and after a period of time (effective pot life) loses it's capability to "etch". The biggest problem with etch primers is misuse by applying too thick a film and trapping solvents, which contain some acid. Proper application for the job is the key. My favorite system for sandblasted rusty old car bodies is, sand the sandblasted steel with 80# DA--clean with wax and grease remover-- 1 or 2 medium wet coats of mild etch primer---and after the proper flash time--- followed by 2 coats of compatible hibuild urethane 2K primer. That system has been holding up for me. I'm not against good epoxy primers (and I DO mean the good ones), but I like the idea of converting the hidden rust left in the pores of the sandblasted steel to iron phosphate. overspray
Beginners at bodywork and paint should be required (by LAW) to read all of overspray's posts here. I've NEVER read anything he said that seemed wrong, misinformed, or even slightly "off". He has the best technical explanations, easily understood, and totally correct. A lot of us "veterans" tend to leave out details, important small things, because we are so used to doing it, we don't think about them any more. Overspray doesn't miss a trick!
i guess i could have got more tech ..i dont spray it over all the filler just up to were it is feathered out .ive used dupounts variprime for years you cant fill over it but ive never had any problem with doing it this way thanks ..
That works OK, too. I just have all this info collected over the years, stuck in my head. Every once in a while it leaks out. I was fortunate enough to pick the brains of some really talented and knowledgeable individuals, and I asked a lot of very pertinent questions just as these euro based systems were hitting the US markets. I especially liked picking the brains of the guys that made the stuff. They tell it exactly as it is without all the sales ********. I can see where I might have to put in another call to the "King" and see if he will do another tech video. Also, it's great (the HAMB) to have guys put in their comments and experience to help new guys like "billsat", who want to learn and give it a try themselves. Keep it flowing. overspray
Absolutely. I love getting "schooled" by Overspray. I especially love to learn new methods from him that are different from what I have come to know and love. He doesn't just tell you; he tells why, how, when, if. Anyone can spat the "right way" to do it.
and his videos are the ****... everyone that's thinking of painting should watch them.... ttp://www.jalopyjournal.com/forum/showthread.php?t=296506 .
hey overspay ive used so many clears ..and still havent found one i like yet .what have you used that will work good with out a bake booth and can be cut and polished with ease ? oh and wont break the bank ?
Since this thread is going so well, any of you guys have experience with TCP Global Kustom Shop paints, primers, epoxies?
The Jalopy Journal
