Spot shooting Epoxy

T

tmwoodall

All - I am trying my damndest to get this epoxy to work in my garage. I am using the firewall as a learning experience for body work, shooting, sanding, etc. I am probably on attempt 12-14 with 18-20 coats. Various reasons for the reshoots (filler showing through, pin holes, sanding scratches, etc).

I have the base in good shape and if I could get a clean coat of epoxy on I'd be done, as I am using the black as my finish coat. Problem on last two or three passes is tiny bits of trash here and there. It comes out great except those few dust spots.

My question is, can I sand those out with 400, and spot shoot just those and it blend in. Or with the epoxy is it a total coat or nothing, when using it as a finish coat? With the semi gloss nature I assume there is nothing I can use to just buff those out and maintain a uniform finish.

For the record, I know i need to setup a real booth at some point. Just hoping I can get the firewall done without one.
 
here is an image, I circled the spots in red. They are very small, in fact you have to be almost totally parallel with the firewall to see them at all. I sprayed the shop out, had a fan pulling for about an hour before shooting, wax and grease remover with time to dry, then tack cloth just before shooting.

I am sure it is just dust in the air. I made plans for a booth last night just hoping to avoid the cost just yet.

Gun - HF Purple, 1.4 tip. 120 PSI at the wall ~38 at the gun regulator. The texture with the slight bumpiness to it is what I want. It is just the damn specs getting under my skin.

Question remains can I spot shoot those blemishes after sanding or will it show up splotchy? markupfwall.jpg
 
hard to tell. from pic. need close ups. did you take that gun apart and clean it out real good, as well as the regulator with solvent after you bought it? it looks like assembly grease contamination but i cant tell unless we see a macro / close up shot. when i bought a gun regulator from hf it had so much grease in it i didnt even bother using it! i wont use a cheap gun anymore, unless its an undercoat that is going to get sanded
 
form406;20540 said:
hard to tell. from pic. need close ups. did you take that gun apart and clean it out real good, as well as the regulator with solvent after you bought it? it looks like assembly grease contamination but i cant tell unless we see a macro / close up shot. when i bought a gun regulator from hf it had so much grease in it i didnt even bother using it! i wont use a cheap gun anymore, unless its an undercoat that is going to get sanded
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You know, that may be it. I have been puzzled as the first several rounds had NO trash in them and the garage was waaay dirtier, with a worse ventilation setup in place.

I left the gun full of solvent sitting overnight once thinking I could clean it up next day, but some of it gummed up. I cleaned it up, I thought well, but I bet anything I didn't and that is my issue. Would certainly explain why now after ten coats and a cleaner garage, that I am starting to get trash in it, and why it is down in the paint, not on the surface.

Idiot.
 
youre not an idiot youre learning...most dust comes off of myself. i get very little from surroundings...
 
You know, I bet that is part of it too. Previously I was blasting myself with ~90PSI from the blow gun before tacking off the truck. I bet between the two I solve my issue. I'll scuff and give it one more shot before I setup a legit booth.
 
What I am spraying comes out with a bit of texture to it, which is how I want it. Smooth, but textured. It shows with a nice slight gloss but very lightly textured. I certainly am not one to be a model (See above, as I am on around coat 20). In that pic there I did also run out of paint just in that patch so it came out just a tiny bit drier than the rest.
 
Update: I built a booth, bought a tyvek suit, new tack cloths. I cleaned my gun for about three hours until it was absolutely spotless. Drained the inline filters, etc. Basically did everything possible to get a clean spray this time. I went out to spray, and set my pattern. I noticed a few spots like I have been getting in the finish. So I figured it was the gun.

Wrong. I opened it up and the epoxy in the cup had tiny particles here and there. Thinking it was the cup, I pulled a new disposable cup off the shelf, and put the epoxy through two paper cone filters to try and pull out whatever it is that keeps ruining my paint. Shot it and of course tiny bits of trash showed.

So now I have taken control of the environment, cleaned my equipment, and discovered the culprit is far earlier in the process.

So I can only think of four things that could cause this: Mixing cups, I re-use sherwin william cups, that are cleaned perfectly the sprayed out with 125 PSI blow gun. Possible but not likely that is the problem. Could be cup on the gun, but same there I clean it the same and blow out. I use a blade type mixer to both mix the epoxy before I pour it from the can and again when I add the activator. Could be the HF paper cone filters I am using. None of these seem that likely, but i guess the filters is the most likely.

Anything else I could be missing, that would cause very tiny specs of something in the epoxy before it hits the gun tip? Planning to buy new mixing cups, and some cone filters from paint supply.

I also am looking at moving over to a Razor Sharpe 1.8 Primer gun instead of the 1.4 HF gun, as I know it is in perfect shape and a far nicer gun than the $30 HF junker.
 
The inside of you air hose is breaking down and sending particles through the gun. Put a gun filter on to verify-you can cut it open later and inspect the paper filter, use the fine waterbase paint strainers-some strainers are just to coarse.
 
Bob, not to say you are wrong, as I clearly have a LOT to learn (which for the record is why I am so hell bent on getting my firewall flawless, so when I get to actual base/clear on the body I'll understand what I am doing). But, if it was the hose, why would the paint in the hopper be showing the particles? Seems if it was the hose, that would be happening when the paint is epoxy shot and the air atomizes the epoxy, no?

I now realize, I had the in gun filter upside down (image attached, I had it the opposite of this), likely not doing a thing for me.

I have an air/oil separator attached to the end of the hose just before the gun, and now realize this may be a mistake. http://www.harborfreight.com/air-tools/air-tool-accessories/oilwater-separator-68246.html

I'll pick up some better strainers, and a disposable inline filter today and try again. The advice an patience of you all is fantastic. I appreciate it very much.

Anyone have thoughts on me jumping up to the real gun despite it is a 1.8 tip and I am just trying to lay a finish coat? I have more than enough epoxy on the firewall, plus some; now I just need a clean finish coat. I've read through other posts and it looks like I can bump the pressure and spray with the 1.8 just fine, especially if I let it induce for a few hours.filter.jpg
 
Someone correct me if I'm wrong but doesn't Barry recommend to ditch the inline gun filters? I don't recall the reason other than it causes issues with flow. I bought the same HF gun for shooting epoxy and a Grizzly for base/clear. I hope you get it figured out and am looking forward to seeing what you find is the culprit. Good luck!
 
Also, for the record, they are so small that in the wet paint I can't really feel the particles between my fingers. And Even in the finished paint 1 in 2 or 3 you can't feel. They show up when looking with a light via refections. So whatever it is is really small.
 
spray some clear on white paper and see what happens... the spi csi spray detectives will work on this!
 
I totally would, but all I have at this point is the epoxy. I'm switching to the Graco-Sharpe Razor gun tomorrow. Bought better paper filters, new mixing pails, and an inline water/dirt disposable filter. I'll snap some high res shots of the paint cup if I get the same junk in it this time.
 
Rustbuster77;20725 said:
Someone correct me if I'm wrong but doesn't Barry recommend to ditch the inline gun filters? I don't recall the reason other than it causes issues with flow. I bought the same HF gun for shooting epoxy and a Grizzly for base/clear. I hope you get it figured out and am looking forward to seeing what you find is the culprit. Good luck!
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Yup the inline will work but it does restrict flow but if the air system is contaminated it would show up in the filter, the little cup screen should also be tossed-if you're filtering the paint there's no reason to have it in there.
 
i had the same issue with the small particles on my sheet metal. so after i waited 30+ minutes after applying the grease and wax remover i blew off the panels with air and with a gloved hand went over the metal. that aleviated about 90% of the trash. but i really dont know anything i just started painting myself
 
Mccann, sounds like you need a tack cloth. That will take care of the dust and junk you can see (and some you can't). I changed to the nicer gun, that and the new filters did the trick. I got a total of three pieces of trash in the last coat as compared to ~20-40 little dots of dust in previous runs. I also covered the whole rest of the cab in plastic in case it was little bits breaking free from around the area as I painted. I am wetsanding and reshooting today.

Man what a difference a nice gun makes, I can't say I am displeased with the HF gun, and for shooting base layer of Epoxy it will be my go to. However that Sharpe Razor is way nicer. It puts the paint only where you lay it down. It is far more precise and sprays better.
 
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