RE: Bubbles?

> The only thing that I can think of is contamination from the upholstery
> machine. What do ya'll think? Any place else I should check?
> Chap



Hi Chap,

I was in a rush to get a top stripped a couple of months ago and I used a 
consumer stripper.  After I stripped it, I rinsed it with Acetone to take any 
residue away.  Then I did my usual sanding, staining, and topcoat.
After I sprayed it with a top coat and it dried, I noticed bubbles through my
topcoat.  What I later learned is with this stripper, you have to wait a day
after you strip to proceed forward.  

So my guess is, if you are doing everything the same with the same 
products, it is probably some type of contamination(upholstry cleaner)
you are getting under the top coat.

Dave B.


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Chap,
    
Do they do any type of fabric protection near your booth?  
I had a similar problem with scotchgard getting in my stuff.

Ty Faragothe

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Chap,

if it looks like solvent bubbles you may want to try adding some retarder 
to slow the drying time down so that the surface doesn't dry before the 
solvent has time to flash out.  Had there been any increase in temperature 
in your area what would make the surface dry faster than usual?

This may be too simple an explanation but may be worth a shot.

Hope that helps,

TonyA


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Chap, 

What about the air movement and temperature in front of the booth?  
If (under certain conditions) warm dry air is pulled too rapidly over the 
wet surface of the lacquer, the very top surface can be partially dried 
too rapidly, trapping solvents in the film.  As those solvents attempt 
to leave the film, they may form bubbles, and if those bubbles pop 
right at the surface, pinholes.

The solvent mix, thickness of film, and the lacquer itself can be factors.

Consider, and measure these also, as appropriate. 

Greg Williams

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Chap,

The bubbles are forming because the coating you are putting down is flashing 
off too fast and trapping gases from the wood.  The air movement in the booth 
is making the difference.  Try adding some flow improver or retarder, or even 
thinner.  Putting on a lighter coat might help, but stick in the 4 Mil wet range, 
if you can, and try not to reduce more than 10 - 15% overall.

Michael R
KC

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Chap

I have run into this before. First what type of finish are you using?
The majority of the time when I have had this happen it has been with 
pre-cat/lac. If you are using lacquer, the odds are your coating was too 
heavy. ML Campbell's Magnalac requires no more than a 5 mil thickness 
wet. If you exceeed that, you create bubbles, fisheye, or the likes. 

The cure for this is to sand down the finish as you usually would and 
re-apply a light, thinned coat again. All you want is just enough to 
create the "wet" look again.

Hope that helps - if you were using pre-cat that is.

Bruce Chadima

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Possibly just too high humidity in the immediate area from the items 
drying. But I think you definitely found the source of your problem. 

BrianMc




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