What did I do wrong with this batch of epoxy

[jtfx6552]

I've been using the black epoxy for awhile on this project with the occasional hiccup. last time i sprayed it, my Finishline 3 kept dripping from the tip and I couldn't figure out why so I shot that coat with my detail gun.

I took apart the finshline, and thought I had everything squared away, except this coat went on real weird. I'm not sure if it was a problem with the gun, the settings on the gun, the epoxy, or the moron applying it?

I first noticed it was laying all orange peely, no matter how wet I tryed to lay it on. I played with the fluid knob, raised the air pressure at the inlet from 23 to 25+ psi, and everything still seemed weird. occasionally, it seemed to "lay" right but for the most part I couldn't figure out what was going on. It has cured for about 6 hours, and in spots it dried totally flat. In other spots it dried almost normal, and in a third spot, it is shiny like usual, but it looks like it has sand in it. I am 99% sure that the area with what appears to be sand is not really particulate contamination.

Here are two pictures, the first shows the flat area and the shinny areas adjacent, this was the same batch of epoxy, induced at the same time, sprayed continuously.

Here are the bumps from the other side of the car:

Once I figure out what was wrong so i don't do it again, can I just sand out the flaws and recoat?

 

[ryan1]

couple of thoughts, gun is probably dripping because the needle is not seating in the fluid nozzle ,probably due to being dirty.or faulty return spring.

as far as the epoxy goes,did you reduce at all ? strain the epoxy , stir thouroughly in a solvent resistant container?
the picture is hard to see but it looks like it could be solvent popping(over applied no flash time),contaminated air,dry spray from being unreduced,contaminated surface or a combination of all.

once it is dry you can sand it out and give it another shot,just make sure none of the above is plaugeing you

 

['68 Coronet R/T]

Once you start sanding it see if it turns into little pits when you break the tops of those bubbles off. Looks like solvent pop to me but hard to tell for sure.

 

[jtfx6552]

Solvent pop makes sense since I kept adding more and more material to try and get it to flow out. The question in my mind is, why wouldn't flow out?

The two thoughts that come to mind are, I was out of mixing cups, so I mixed and induced in my dekups liners, then I just picked them up put the gun on and sprayed, I didn't re-stir or pour or anything, induction time (or separation or settling time, lol) was about an hour and 20 minutes.

The other is something wrong with the gun. the reason it was leaking from the tip was there was gunk on the needle behind the packing nut, which kept the spring from pushing the needle in against the seat. I took the needle out and let it sit in lacquer thinner for a few days, and eventually the gunk came off. I only scraped with my finger nail to do it, so I think the needle is fine. I didn't re oil the needle where it goes through the packing, and I think I forgot to tighten the packing nut when I put the gun back together. Not sure what if anything that would do to make the gun spray poorly?

 

[PatG]

My gun spits when I fail to tighten the packing nut on the needle. I now leave the packing nut in place and clean the gun without removing it. Pros told me I didn't need to remove it after every spray session. Hope this helps.

 

[toofast415]

I'm no pro by all means, but I had a similar situation. I later found out that my cheapo desiccant bag tore in my air line dryer.