Bumps in epoxy primer... what am I doing wrong?

black is the only one i have any trouble with. i use a mixer blade in my screw gun to stir with. then do the fat man shake on it .
that hf gun at 50 lbs is blowing a lot of dry spray out while your painting. northern tools sells vaper guns cheap. they are much better than the hf purple junk .
The HF (Harbor Freight) purple series spray guns are now being replaced with HF #68843 gun of which is superior to purple guns, I have expensive Tekna Pro-Lite guns but use the HF 6884 3gun for a workhorse for primers, the HF 68843 only comes with a 1.4mm tip so wont work for primer surfacers UNLESS you precisely machine the cap to 1.8mm for surfacers. I save my Tekna for clears or metal or peral base coats. I did a YOU TUBE video showing how to marry a HF 68843 gun with Devilbiss Dekups system. Im able t o spray as low as 20 PSI (in some cases) with this HF gun, most important criteria is 3/8" min ID of air hose 25 feet length best max, and use 3/8" air coupler or 1/4 inch "high flow" air couplers made all the difference for the HF gun
 
Bringing this thread back from the dead...

Since posting this thread we've moved houses. So I had to tear the garage down and I'm now rebuilding my setup in the new house. In doing so I took a closer look at the Kobalt filter / water separator. I found that it was contaminated with oil. When I blew through it (backwards), oil was pushed out of the filter element. Then when I inspected the air path on the other side (out direction) of the filter and through the regulator, there was oil coating everything.

So I think my issue was oil contamination.

I'm running new copper lines in the new house and I've got a Devilbiss QC3 filter/dryer/regulator. I'll let you know how it turns out.

I'll still run the old water separator and regulator setup for tools and keep the QC3 just for paint.
 
What are you going to do with the compressor before it contaminates your new system?

I was going to use a M60 (it's cheaper than the M30 on Amazon!) toilet paper filter in the air line and then have the QC3 on the air branch that is for paint. I'm not super worried about my air tools... they've lasted this long without any problems. I will be sure to use the clean air line when blowing off the dust before paint.

Is there anything I can do short of getting a new compressor? That's not really an option right now.

I was just happy that I think I found the source of my paint issues since the cheap Kobalt filter/dryer was passing oil through it. I figured the M60 + QC3 would provide clean air even if my compressor is spitting a little oil into the lines. Is that an incorrect assumption?
 
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Stay tuned, some of the guys here have done a lot of work on their compressors and can give you some suggestions, but I would want to get it repaired before starting it up again.
 
Stay tuned, some of the guys here have done a lot of work on their compressors and can give you some suggestions, but I would want to get it repaired before starting it up again.

I've had my compressor for about 10 years and I don't remember ever putting any oil in it. I even have a bottle of compressor oil I bought a bunch of years ago and it is still sealed at the cap. And when I check the dip stick, it is still up to max. The oil looks pretty clean too.

I was thinking the residue in the filter and regulator was normal and that the filter was doing a poor job of filtering it out.
 
Couple comments:

50 psi is way too high imho. 30 psi or so....
Don’t spray your first coat thick. Nice thin coat or it will crater....
Wait at least 30 minutes after wax and grease remover
Lint free cloths usually are not when used over rough bare metal, especially blasted metal
Don’t get aggressive with your tack cloth. Gently roll it, don’t rub it in...

Don
Agree with 30psi max
most likely spraying too slow and too heavy.
Cheap guns, cheap compressor, inadequate dryer not helping anything.
 
I know this is an old thread, but did you find a solution? I have the same problem with tiny bubbles as I'm spraying. If I use a paint brush, I get the same issue. Approx 20 deg Celsius in paint booth.
 
I know this is an old thread, but did you find a solution? I have the same problem with tiny bubbles as I'm spraying. If I use a paint brush, I get the same issue. Approx 20 deg Celsius in paint booth.

The only way I know of getting bubbles (on the first coat spraying) is if wax and grease remover looks dry but still in the pours?
Brushing this is common if the second coat is applied too soon as it moves the first coat, brushing I do very often in small areas and I do a coat and second coat 2 to 4 hours later because brushing doe not blow out the flash solvents like a paint gun does and slows everything down.
We need a little more facts to help out.
 
I shoot epoxy with my iWata LPH 400 1.4 tip at 22 psi. 3 turns out on the fluid.
Shot two coat of white yesterday to seal this hood unit:
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The white is much more difficult to spray IMHO because it doesn't cover as well as the black, thus my tendency is to spray it too heavy by going back over an area that I didn't think covered well enough. If I just trust my spraying technique everything works fine but going too heavy produces fish eyes.

I spray the black with the same gun and settings:
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It's hard to get a photo of the bubbles, but they cover entire area. Photos are of Imron 3.5 but I got am getting the same issue with the epoxy primer. One of the photos shows the plastic cup of paint with bubbles. When I paint over primer or primer over bare metal, with or without cleaning solvents, same issue. It appears better if I thin the paint and place very thin coats, but they are so thin that the surface gets patchy with variable sheen.

Using a pro-tek gun with 30 to 40 psi. I've seem other posts where painters say that there are less bubbles on vertical than on horizontal panels. I'm going to try placing panels upright today to see if I can improve my results. And try with more thinner in the Imron. Imron says up to 25%, maybe I'll try 35%.
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Also what are your cleaning steps and times?
Some are solvent pop and some are gassing so two different issues here.
 
Waaaaaaaaay, waaaaaaaaaaay too heavy. Without changing technique setting them upright will just make runs.

First like Barry wanted to know your cleaning steps and the time you wait between cleaning and shooting are critical. Read this for how to wipe down a vehicle: http://www.spiuserforum.com/index.p...ay-to-wipe-down-a-vehicle-prior-to-paint.6622
If you are using a waterbased W&G remover like SPI 700 you have to give it enough time to dry. 30 minutes minimum but you would be better off waiting 60 minutes.

Now you need to adjust your gun. Here are some general guidelines: https://www.southernpolyurethanes.com/general-gun-adjusting
I'll try to give you a little more guidance on gun setup. Take a piece of masking paper tape it to the wall. Set your pressure at 30psi to start. Turn your fluid knob all the way in (closed). Open your fan knob all the way (full open). Open your fluid knob 2 full turns and pull the trigger. Observe what your pattern on the paper looks like. Adjust till you have an even and medium wet pattern.

Applying the product. You need to take whatever you are spraying and make imaginary straight lines across/through it. Then when you are spraying you need to spray in those straightlines. That is called tracking. Your gun will probably shoot best 4-6 inches off the surface (that is up to you to find out though) As you are spraying as you complete a pass you then want to overlap the first pass approximately 50-75%. With the epoxy start at 50% and get closer if you need too. This is very important. Remember straight passes and consistent overlap. Never double coat or spray more on an area you just sprayed.

After you have shot your first coat of epoxy. Observe the proper flash time. Minimum 30 minutes, but for this exercise until you start seeing positive results give it 60 minutes between coats. Do not rush another coat on. If you don't have the time wait until you do.

Watch what the product is doing as you are spraying. Move your gun faster (passes) than what you have been. Dryer is better than wetter when spraying epoxy. Realize it takes time and practice to become proficient. Keep asking questions here if you need to.:)
 
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