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Texture in Reduced Epoxy Primer

Hello, I recently shot some gray SPI epoxy primer reduced (slow reducer) 1:1:1 as a sealer over some gray SPI 2k. I am getting a slight texture that is slightly larger than overspray, but can't be seen from a few feet back. I am confident in my air setup running a refrigerated dryer and a 1 gallon desiccant separator in my booth. Unreduced epoxy sprayed fine, as well as some Euro clear the same day with no indications of water contamination. Should the reduced epoxy lay out totally flat? Did I add too much reducer? Could this be overspray from an improper gun setup? On this particular project I'm spraying a gray color with huge amounts of metallic flakes, terrible coverage and you can see everywhere the metallics fall differently. Its crucial that the sealer be 100% uniform. I can sand down the reduced epoxy, but that defeats the purpose. Any tips or thoughts on using SPI epoxy primer as a sealer? You can see the small imperfections in the image below.
I'm not sure what we're seeing there, but if you need a smoother surface, you might put a couple coats of base on and sand that a bit (if it's allowed) or spray a wet coat of less reduced epoxy, sand that, and paint it within the 7 day window when it is still acting as an adhesion promoter for the base.

The reason I'm saying all this and not trying to suggest how to lay the reduced epoxy flatter is that there are too many different things that affect it. But maybe you are putting it on a bit too heavy, it should be like a coat of basecoat, just enough to stick well to the primer and have base stick well to it. It doesn't need to be a full, wet coat.
Thanks for the responses. I was hoping this was something common I was doing wrong and could be identified quickly. I attached another picture showing what I was talking about. It was shot with a HVLP 1.3 Devilbiss SLG that I use for epoxy, just never used it reduced as a sealer. I realize thats a terrible gun, but still never had issues when spraying unreduced epoxy. I am spraying HOK Galaxy Gray which as stated above, covers terrible and shows literally any inconsistent colors in the primer no matter how many coats of base I apply. I usually don't have issues spraying directly over wetsanded 2K. I did end up wetsanding these little nibs out of the epoxy, just was hoping I could put the base right over the sealer, but with this many metallics I knew those little buggers would show up.

What am I giving up the more the epoxy is reduced? What would be the problem with reducing more than 50%?
With Euro on top, final product came out nice, plus I found a great use for those white SPI boxes :cool:.

I also get those little bumps with epoxy. Though I have never got to the step of base/clear, so I don't know what would happen if you leave them. I also spray epoxy with a cheap Devilbis gun. I have come to the conclusion that this gun dry sprays at the outer edges of the fan. I think it is either dry spray globs, or the epoxy not strained fine enough. Since this is for primer coats only, I'm not going to worry about it. For the final sealer coat I will use my base/clear gun. Or for the final coat of epoxy, don't reduce and wetsand 600.
Had to revive this thread. I again used unreduced epoxy with no problems and tried to mix some up as a sealer and ran into similar issues as described before. I paid particular attention to the particulates ;) in the strainer this time. Here's what I found. Why would the epoxy be reacting this way? All 3 parts 1:1:1 came from "sealed" containers. The epoxy is a little older date code 09/16. The strainers I had been using were 125, but clearly this gunk is getting through, and or forming in the paint gun. You can see a bubble in the bottom of the paint cup seemingly as a chemical reaction.

2 years old, looks like sitting for so long the pigment had started to clump together. as with any paint it settles over time. this looks like it just hasnt redissolved all the way. if epoxy gets old it is still good as a primer but i prob wouldnt be using it for sealer on something that needed to be a flawless finish. in any case what you do here is seal with 1 coat, put on 2 coats of base. let sit an hr then go in with some 600 or 800, denib it then do the last 1 or 2 coats. honestly, for something that had to be really perfect then this is what you should be doing anyway.
Thanks for the response. I actually am thinking it may be a combination of the two responses above. Lets say all things equal if I used a paint stick with dried epoxy on it the added reducer may help break that down off the paint stick when a standard mix of epoxy may not? I don't recall if the stir stick had dried epoxy on it or not. Obviously I wouldn't mix base or clear without using a new stick. It is also the bottom quarter of the can and could have had air contamination over time? Even when sealed wouldn't that mean 3/4 of the can is full of air? Frustrating, I love the epoxy just never got it to work right as a sealer, so far.


Paint Fanatic
Staff member
It is savable if you have not used too much of it that way.
First this is why we say if not using part A for a while every 60 to 90 day flip the can over, this stops the pigments from clumping at the bottom.
The fix! scrap with paint stick the bottom and mix with stick and than and only then put on shaker for 10 mins.

However what i see in the cup is not pigment, pigment will go though a strainer as average size is 6 micron, its trash from like said, a paint stick or dirty container introduced after strainer.

There is nothing in it that can cause a reaction.

Also i don't care if clear, an SS or epoxy bubbles in cup mean nothing.
We made a 300 gallon batch of something yesterday and the 16" blade speed was about 8000 rpm, I dipped out 1/2 a quart while blade was running and it was full of bubbles to spray and no way a bubble is going through a gun.
I do this same thing 2 to 3 times a day.
Thanks Barry, always makes me feel better to hear from the expert! This sounds like it should be a simple fix. If it's not a chemical reaction then extra care mixing and straining should solve my issue. Got a lot of time into this current project and have been fighting coverage issues with the House of Kolor paint chosen. That's why the sealer is so important this time around. Just have to finish the tailgate on this Toyota.
yes but epoxy is slow and cant be sanded for quite awhile. this would put a complete halt to your spraying process. what should be done is epoxy sealer then a couple coats of base, denib the base and spray the last coat or two then your ready for clear.
Waited 24 hours and wetsanded with 1500, then shot the base. The epoxy was still not completely "dry", but the water allowed me to sand. The nibs were small enough that the base covered just fine. Took more time to make this thread than it did to sand on this small part. Finished with Euro and looking good :cool: