Other Urethane Basecoat Problems

rashin

rashin

Location
Northwest Indiana
Ok, for all the paint experts:... Im attempting to spray std. basecoat, and having some problems. The paint forms small inclusions, bubbles, whatever you want to call it right after it comes out of the gun. I am using a cheap harbor freight hvlp gun. Air is very dry. Pressure at gun is around 10 psi. Paint is Martin Senour automotive bascoat from NAPA (Thinned 2:1).

Here is a video: (Disregard I am spraying on a bin. It does this on anything).
http://www.youtube.com/watch?v=2KwQHw8TGgU

Closeup picture:
IMG_20121120_182203.jpg
 
Brian_216

Brian_216

Location
Harveys Lake PA
From what I can tell by looking at the pic on my phone it looks like surface contamination. What did you prep the surface with as far as cleaners go? Try using rubbing alcohol in a sprayer and a lint free cloth then tack with a tack cloth. Did you wash the gun out with anything before you put the paint in it? I have seen this happen and most times there was something on the surface. One other thing, some compressors have a water trap on the outlet, and smaller ones for construction (air nailers etc) have oilers that add oil to the line. Just random thoughts..
 
Hogggman

Hogggman

Stock Sucks
Location
White Lake MI
Did you try spraying it on anything else those plastic bins could have some sort of mold release or the plastic itself could have some sort of oil in it. Try spraying it on some masking paper or news paper and see if it does the same thing. It's called a fisheye and is usually caused by a oil or silicone on the surface.
 
rashin

rashin

Location
Northwest Indiana
Like I said it does it on anything that it is sprayed to. Paper bag, piece of wood,... superjet hood! :)

Air is dry, I tried two different compressors and lines. I added an inline dryer as well.

Any other thoughts??
 
DarkWater

DarkWater

Down Side Up
Location
waterford, MI
Do you weigh your mixture or just use a cup?
Are you using the manufacturers suggested ratios?
I've used H.F. guns before with good results but you need to play with the settings. 10lbs seems low to me.
Moisture will accumulate in the hose itself. Its a great idea to have an inline filter and a regulator just at the base of the gun.
 
rashin

rashin

Location
Northwest Indiana
Ive used the harbor freight guns with much success. The guns have seen lacquer in the past (cleaned and dried out since). Could that be causing this? I am going to try a different gun later tonight.

Inline filter was at the base of the gun. A new hose was used.

Ratio was measured with a painter's cup. It was pretty accurate. The basecoat doesnt use a hardener, just reduced 2:1.
 
jetpilot808

jetpilot808

Location
USA
Same here, used the H. F. guns with sucess , super dry air. If I remember right the psi was around 30-40. Used a psi gauge at the gun for accurate reading. The guns are like $12 with coupon, never cleaned them up, just dispose of them and use a new one every time. Only time I got clumping of anykind, if there was some leftover residue on the material, but it happens for you everywhere....it's gotta be in the gun or the tank. Elimination process.
 
DarkWater

DarkWater

Down Side Up
Location
waterford, MI
Ive never had that bubbling happen to me. But it does seem like something chemical. If its happening on all surfaces, i suggest a new gun, then perhaps contacting The place you bought the paint.
 
Scraggly

Scraggly

Location
hhh
tear that gun down and clean with acetone, let it dry and reassemble wearing gloves or something clean.
looks like it could be oil left on the parts of the gun from manufacturing. or finger oils from assembly.

long shot, but all i got.
good luck
 
Zeon

Zeon

WNY Crew
Location
Buffalo, NY/ Crystal beach, Ontario
I spray EVERY day, I have seen this a few times...... It honestly Looks like oil/water in the lines (ive had it happen with my old compressor) im not sure what kind of Dryer/oil seprator you have but even with my $600 Desiccant dryer from devilbiss I have issues every so often if I do not change the desiccant. After putting in an oil trap/water seperator on the compressor, and put a desiccant dryer/charcoal filter by the paint booth, I am still only 95.7% pure dry clean air.

Try a tack coat before you lay the paint on heavy as well. Give her a medium/dry pass first, then give her a nice medium to wet coat

If your using Martin Senour (which I use in shop) did they give you TRS4 medium stabilizer to reduce it? If not, Which stabilizer did they give you to reduce?

Wax and grease remover (buy the real stuff), Wipe down , trying to not rub into the surface. Buy a few prep towels. No rags, no papertowels.
 
rashin

rashin

Location
Northwest Indiana
Maybe it is my compressor I'm not sure. I have had problems with my husky two stage compressor in the past, so I used my ridgid contractor compressor. I hooked up a cheap HF dessicant dryer, and new lines.... Im skeptical that there is any water or oil in the lines but im not going to rule it out.

The paint is a Martin Senour Cross/fire basecoat (not sure of exact paint), with CR732 reducer, mixed 2:1...

I'll see what a new gun does later....
 
rashin

rashin

Location
Northwest Indiana
The problem was there no matter what compressor or dryer I used btw..... So,... maybe gun??

Could temperature be an issue? My garage is heated but I only turn the heat on when Im in it. The paint still could have been cold from the night before... Maybe around 45-55 degs.
 
Zeon

Zeon

WNY Crew
Location
Buffalo, NY/ Crystal beach, Ontario
rashin said:
Maybe it is my compressor I'm not sure. I have had problems with my husky two stage compressor in the past, so I used my ridgid contractor compressor. I hooked up a cheap HF dessicant dryer, and new lines.... Im skeptical that there is any water or oil in the lines but im not going to rule it out.

The paint is a Martin Senour Cross/fire basecoat (not sure of exact paint), with CR732 reducer, mixed 2:1...

I'll see what a new gun does later....
Click to expand...

Ohhh ok, you are using Crossfire and Not Techbase. Reducer works perfectly fine on that application. (this wont solve your problem but if your crossfire paint seems thin, you can reduce it 4:1. On flourescents, yellows, and poor coverage colors, ill even spray it out straight)

As for your "contamination issue" how old is your compressor. If your using under a 60 gallon, id personally leave the petcock cracked just a bit to let minimal air out, and any thing on the bottom while you paint.

I just saw your video as of a few seconds ago as well.... Honestly it looks like moisture and oil coming out with your paint.
 
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