2k urethane over bare steel.

R

Robbie mcmillian

Hi guys, I'm new to the fourm. Just wondering if any of you guys spray urethane primer directly over your very small bare metal cut- threw areas or do you take the time to spray a coat of epoxy over them before recoating?
 
Robbie mcmillian said:
Hi guys, I'm new to the fourm. Just wondering if any of you guys spray urethane primer directly over your very small bare metal cut- threw areas or do you take the time to spray a coat of epoxy over them before recoating?
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The size of a quarter or smaller? It's done every day on collision shops and they seem to get away with it, no come backs.

Not saying is the right thing to do, just speaking from what I see every week at the shops I do business with.
 
this is the only thing i use self etch for. if i have tiny cut throughs of bare metal showing anywhere i will grab a rattle can of it and quick just hit the spots before i 2k. this is assuming they are not all over the place. in which case i would just seal the whole panel with a quick thin coat of epoxy
 
It gets done all the time at Insurance shops. Not saying that's correct but it does. I work Collision Repair and I do what Jim does and use some SEM self etch on sand through's. If it was mine, or a high quality job (not Insurance type stuff) then I would take the time and shoot some epoxy.
 
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Thanks guys! What's your take on some of these other companies 2k that (claim) to have a high build DTM 2k? I've been hooked on spi clear for several years but I'm not real familiar with the spi 2k primers.
 
Robbie mcmillian said:
Thanks guys! What's your take on some of these other companies 2k that (claim) to have a high build DTM 2k? I've been hooked on spi clear for several years but I'm not real familiar with the spi 2k primers.
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Use SPI and don't look back everything SPI smokes the other companies products. You won't be disappointed with SPI primers in any way.
 
Robbie mcmillian said:
Thanks guys! What's your take on some of these other companies 2k that (claim) to have a high build DTM 2k? I've been hooked on spi clear for several years but I'm not real familiar with the spi 2k primers.
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What I've learned from Barry is that just because it's labeled "DTM" that doesn't really mean anything. You are going to get the best adhesion and corrosion protection using a epoxy primer like SPI And SPI's epoxy is probably the best on the market.
 
I never have seen a dtm 2k primer in the big companies premium lines that I have worked with in the past, I think it means something... Rattle can self etching for small burn through for peace of mind, I use ppg sxa1031. It has to go on thin, don't over do it, more is not better.
 
I used rattle can etch one time, and it wiped straight off with lacquer thinner after it was cured. Is there some "etch" effect left behind despite this or is it just garbage - not saying I used SEM, I can't remember what it was.
 
It remains a 1k product, and being in an aerosol can, it doesn't have the acid it has when in 2k form I have been told. I don't expect much from it, I use it when it is just a small burn thru, like an edge. One rattle can, can last for months in my shop.
 
I know in a perfect world it would get a coat of epoxy over cut through's but it's just time consuming on production work. Has anyone personally had 2k to turn loose over small areas? Haha, some of the guys I learned from 25 years ago would strip and prime a car allover with ol lacquer primer and the paint is still on them
 
While anyone that has paid attention on this site knows what is best, real life time & budgets don't always allow it. As said in small amounts, no one will likely ever know unless you let the bare metal spot sit there uncoated long enough to start rusting without resanding or something else stupid that goes against common sense.
Whole paint jobs are done these days with self etch & 2k over metal. Accepted practice by many, just not as good.
I still have much of the same paint on a vehicle I painted back in 98' that had a few minor sand throughs in the epoxy & never showed up, just wouldn't let any go if I could easily avoid it. On an absolute high dollar paint job a sand through really calls for another spray & sand session on the panel for the absolute straightest reflective finish anyways. Also most sand through spots end up occurring out on the main panel faces, not on the more critical areas where you want the absolute best rust protection the most
Cutting any corners is always a personal call, but when you have higher than normal standards you can get away with some.
 
What is the consensus on small rub-throughs and poly primer? For example, according to Evercoat, Super Build "eliminates the need for costly epoxy or self-etch primers over bare metal". Clearly this it would not be the absolute best way, but for a small spot in a non-corrosion prone area, is it really worth spraying epoxy and waiting 24 or more hours?

I think I would use poly on bare metal before I'd use a 1k self etch or urethane. Thoughts?
 
Old days you would never use poly primer on bare metal. G2 and Slick Sand are not recommended over bare metal. Evercoat rep was at our shop recently and he was touting the advantages of the 4:1 poly's which are "supposed" to eliminate the need for epoxy. I don't know if I believe that or not. Me I don't plan to use any poly over bare metal. Epoxy first. As for small sand throughs, it happens all the time in Collision repair and they get covered in either urethane or etch in a can. Most Collision Repair shops never even use Epoxy. Bare steel gets primed with urethanes all the time. Very few shops follow current OEM recomendations about using a epoxy on bare metal. I haven't seen many adhesion issues though at the various shops I've worked at(with comebacks) over the years. Some places were higher quality than others. If anything I've seen more issues with clearcoats than anything else. But if it's something you care about and have spent a lot of time take the time to spray some epoxy.
 
Man this is an awesome forum! I like everyone's input. Thanks guys!
 
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