Can I do this with epoxy sealer?

MJM

MJM

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A little background first. I have followed SPI's standard operating procedure using SPI epoxy from bare metal through filler work up to today. Each material was sanded flat before the next material was used.

I feel I'm ready to move on to spraying a high build poly primer. Here is my epoxy sealer question......

I was thinking of spraying epoxy sealer reduced 10% over the entire car, waiting two days then spray the poly primer. I was thinking the reduced epoxy would lay down flatter over the already sanded and flat panels.

Would I be sacrificing adhesion spraying epoxy sealer (maybe two coats) vs spraying non reduced epoxy that will have uneven texture before the poly primer?

If I can spray epoxy sealer, it will also give me an opportunity to spray reduced sealer thru my Iwata LPH 400 for the first time. I haven't used this gun since I bought it six or so months ago. Need to get some practice with it.

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You will not sacrifice any adhesion, but at the same time there’s no need to reduce it. It still lays pretty slick unreduced and the poly primer is going to be blocked flat anyway. Any peel on your epoxy becomes irrelevant once you spray a high building primer over it.
 
Lizer said:
You will not sacrifice any adhesion, but at the same time there’s no need to reduce it. It still lays pretty slick unreduced and the poly primer is going to be blocked flat anyway. Any peel on your epoxy becomes irrelevant once you spray a high building primer over it.
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I've found that heating the epoxy to about 90 degrees helps laying it down.
 
Okay, majority rule wins by popular vote. One of my another thoughts for spraying sealer vs non reduced epoxy was to keep millage down.

I could probably spray two heavy coats of unreduced epoxy and block out to 400 grit for base. I think the panels are pretty flat and straight.

I'm spraying the poly as reassurance it blocks out straight and flat. I know the ploy won't be very thick (millage) when I'm done blocking it. Like I've already stated, I think the panels are pretty straight and flat when wet checking them.
 
MJM said:
One of my another thoughts for spraying sealer vs non reduced epoxy was to keep millage down.
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Mils of epoxy is pretty inconsequntial when compared to high build 2K or poly primer. And if you do your blocking right the millage will be the same whether you are using epoxy only, poly, or 2K. Now if you don't block enough, then apply more primer, don't block enough, apply some more, then you would have excessive millage that doesn't need to be there. How many mils needed is determined by how straight your car is in metal before you start priming/filler. After that all you can do is get it straight and the mils will be what they will be.
 
If it's that straight, skip the poly and keep going with epoxy. The massive build of poly can be problematic if accidentally left in an area where it shouldn't be. I personally reserve the use of poly to "problem panels" with lots of complex bodywork, never the whole vehicle except in extraordinary circumstances, partly because of how long it takes to make sure all the nooks and crannies are sanded down. Typically you need to go through a wide range of grits to get poly sanded properly. I have started with 100 and gone through 150, 220 and 320 with a single application of poly. It's thick.
 
MJM said:
Okay, majority rule wins by popular vote. One of my another thoughts for spraying sealer vs non reduced epoxy was to keep millage down.

I could probably spray two heavy coats of unreduced epoxy and block out to 400 grit for base. I think the panels are pretty flat and straight.

I'm spraying the poly as reassurance it blocks out straight and flat. I know the ploy won't be very thick (millage) when I'm done blocking it. Like I've already stated, I think the panels are pretty straight and flat when wet checking the
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thats what i do get all the filler work straight and epoxy blocked ou till no break throughs epoxy sanded in 180. couple coats non reduced block with 400 , seal with 20 percent reduced epoxy go to base. when i was using poly primer i would either block it out to 400 and seal. or do a final prime in epoxy and prep for paint.
 
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zachm said:
thats what i do get all the filler work straight and epoxy blocked ou till no break throughs epoxy sanded in 180. couple coats non reduced block with 400 , seal with 20 percent reduced epoxy go to base. when i was using poly primer i would either block it out to 400 and seal. or do a final prime in epoxy and prep for paint.
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i like the consistency of using just epoxy less materials to go wrong and its all the same primer throughout plus if youve ever done test with poly it is fairly brittle epoxy is very flexible and have not seen shrinkage with it
 
In my limited experience, if you are going to spray polyester primer reduce it to the max. Maybe the Evercoat Optex 4:1 I've sprayed was getting old, but I could hardly spray it without reducing as much as I could. (Per tech sheet).
 
MJM said:
Okay, majority rule wins by popular vote. One of my another thoughts for spraying sealer vs non reduced epoxy was to keep millage down.

I could probably spray two heavy coats of unreduced epoxy and block out to 400 grit for base. I think the panels are pretty flat and straight.

I'm spraying the poly as reassurance it blocks out straight and flat. I know the ploy won't be very thick (millage) when I'm done blocking it. Like I've already stated, I think the panels are pretty straight and flat when wet checking them.
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If there’s anything you DO want millage of it’s epoxy. More corrosion resistance and chip resistance.

If your panel is that straight there’s no point in poly.
 
crashtech said:
If it's that straight, skip the poly and keep going with epoxy. The massive build of poly can be problematic if accidentally left in an area where it shouldn't be. I personally reserve the use of poly to "problem panels" with lots of complex bodywork, never the whole vehicle except in extraordinary circumstances, partly because of how long it takes to make sure all the nooks and crannies are sanded down. Typically you need to go through a wide range of grits to get poly sanded properly. I have started with 100 and gone through 150, 220 and 320 with a single application of poly. It's thick.
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I'm basically modeling the paint job from this video, The only difference is I added the epoxy from bare metal thru filler work to get the body panels of the car straight. Now I will be using the poly to sharpen body lines and refine any blemishes. This is also pretty close if not exactly the same method as SPI member RoshronRooster used. I owe SPI member texasking much gratitude for teaching me how to get the car straight by building the body panels up with epoxy and skimmed coated body filler. It's also the way I see SPI member mopar jim get his cars straight.

This thread stems from knowing that every time paint is sprayed, you no longer have a flat panel until it's sanded again. I guess I became fixated with keeping the body panels flat all the way up to spraying polyester primer. Hence the reduced epoxy question because that paint application would be much flatter then un-reduced epoxy if not sanded. Could I spray the poly over sanded spi epoxy, sure but, it would only be a mechanical bond vs chemical and mechanical since I can't get the whole car sanded within two days of epoxy application before polyester.
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UAmember said:
In my limited experience, if you are going to spray polyester primer reduce it to the max. Maybe the Evercoat Optex 4:1 I've sprayed was getting old, but I could hardly spray it without reducing as much as I could. (Per tech sheet).
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I'll have to see how well the Clausen Rust Defender sprays thru my Iwata 2.0 tip primer gun. Worst case scenario, I'll reduce it 3 to 5% with acetone since I'm in the temperature range allowing for reduction.
 
zachm said:
i like the consistency of using just epoxy less materials to go wrong and its all the same primer throughout plus if youve ever done test with poly it is fairly brittle epoxy is very flexible and have not seen shrinkage with it
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I agree with you. I was hesitant about using polyester primer due to cracking and brittleness of the product if abused by excessive build millage left on the vehicle. I won't be abusing the polyester primer so the cons of the product don't concern me.
 
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MJM said:
I'll have to see how well the Clausen Rust Defender sprays thru my Iwata 2.0 tip primer gun. Worst case scenario, I'll reduce it 3 to 5% with acetone since I'm in the temperature range allowing for reduction.
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Check the tech sheet. I am not familiar with Claussen, I would like to try it after being on here. The tech sheet for Optex Super build says to use urethane reducer only.
 
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