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The Body Shop TECH General questions that don't fit in any other forum |
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#1
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SPI primer problem
Today I shot some SPI epoxy primer on a fender, a very light coat followed by two wet coats 30 mins apart.
Looked fine for quite a while as it set outside and dried. Then a few hours later when I went to bring it in I noticed where the primer was over filler that it had a very fine layer of bubbles, like a rough satin finish. The fenders did get hit by the sun for a while, and being in the 80's outside, and being black I'm sure they got pretty freakin hot. Looks kind of like the filler outgassed under the primer or something. At the same time I primed an endura bumper, and hood. Both turned out nice but neither probably saw the sunshine that the fender did. Was planning to block sand and primer again anyway so no biggie ... but don't want it to happen again going forward. Any ideas?
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#2
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The air under the primer in the tiny pockets actually boiled some primer before it cured. The Epoxy primer doesn't dry.... it cures.. have seen the sun do this on a endura nose which had some 3m ez sand on it.
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
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#3
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Did you use waterborne wax and grease remover? How long did you allow before you applied the epoxy?
Don |
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#4
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As Don said, it’s imperative to use SPI Waterborne Wax and Grease Remover when using SPI primer. Their primer is not compatible with solvent based cleaners or acid cleaners. I don’t think heat has anything to do with it because the problem only appears where the filler is (shadow lines). Was the filler completely cured? Or the wax and grease remover you used wasn’t completely evaporated out of the filler when you applied the primer. Filler absorbs moisture, that’s why I think it’s a bad idea to put filler over bare metal. Yeah, it’s the way we did it in the old days, but filler adheres to epoxy primer better than to metal. When it’s really hot out, I reduce with high temp reducer to slow the cure time.
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Last edited by HoovDaddy; 06-24-2022 at 11:36 PM. |
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#5
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Bingo .... woke up in the middle of the night with the answer.
Sent to the wife out to clean the parts with SPI W&G remover .... fender was the last thing she wiped down, I came out of the shop and the fender was the first thing I painted. And she kinda lays the W&G remover pretty heavy Normally I would have done it myself and let them sit for at least 15 minutes ... didn't even think about it because she did the wipe down. Question now ... sand it right back down to filler and shoot again ... or just sand it smooth and shoot again?
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I'm World's Best Hyperbolist !! |
#6
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I need to teach my wife some new skills! Tke that area all the way down until those spots are gone. You'll destroy your filler job and create a big low spot. If it were mine, I'd take the filler out prime it. Then apply the filler over the primer. Applying filler directly to metal will cause corrosion down the road.
Print out the SPI data sheet so you can have a handy reference for the products you are using. You need to let the Waterborne set for 30 to 45 minutes. I always go beyond the mfr. specs.
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#7
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That's one of the most impressive things l've ever read on this forum.
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Greg Reid Palmetto, Georgia |
#8
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Hit it with 600 paper today and it smoothed out perfectly just like the primer on the adjacent bare metal. There weren't really pits, it was much more like a rough'ish satin finish, surface about the roughness of 180 grit paper but without the sharpness, it was slick on the surface. Doesn't appear that there are any adhesion problems.
Wife is my constant helper when it comes to painting, moving saw horses, mixing paint, watching me to make sure I don't drag a hose on something or miss any spots. She also sands and buffs.
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I'm World's Best Hyperbolist !! |
#9
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I have started letting the wax and grease remover sit overnight and I don’t pile it onto filler. Keep it light and blow it dry with compressed air after you have wiped it off. YMMV….
Don |
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#10
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SPI Barry is who to call, he runs the show at SPI, and can answer/help with any issue you have.
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
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#11
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Sounds like my wife...the extra set of hands.
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1970 GTO (Granada Gold) - 400 / TH400 |
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#12
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Take it off.
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#13
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#14
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Quote:
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#15
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I remember getting a rough orange peel type surface with the SPI. Was told it was because coats should be light. Too heavy and it starts to ripple and do strange things. But, it sands away okay.
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#16
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Yep the stuff is great that way, you can sand away just about any problem. These areas sanded away to be indistinguishable from the good areas. And yes I've run across the large frequency peel from going on too thick also.
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