Tiny bubbles...

[pslamp32]

So my last few coats of sprayed polyacrylic (WB poly) introduced hundreds of tiny bubbles in my topcoat. This seems odd because I sprayed probably 15 coats before this using the same poly with no issues. Anybody have any idea what might be causing this. It seems that everytime I feel like I'm close something comes up to make me take a step backwards. This morning I sanded back to 220 to get rid of some scratches I didn't see. Everything was nearly perfect 3 days ago, yet in my quest to find perfection, I keep making it worse! Frustrating to say the least. :tinysmile_cry_t: Thanks.

 

[DaveO]

Did you shake the finish before putting it in the gun, or agitate the gun before spraying? That could have introduced some air into the finish :dontknow:

Dave

 

[pslamp32]

Not anymore than in previous coats. I'm thinking that maybe some dried finish is accumulating in the gun. I've been pretty good about cleaning with water between coats but I definitely haven't taken it completely apart to do so. Mostly just changing the cup with one filled with water and spraying that through. This has been going on for over a week as I try to 'perfect' the topcoats. :BangHead:

 

[TracyP]

Could there have been any way something silicone based could have gotten to your project and is causing tiny fisheyes? Waxes or polishes sometimes include silicone which is an enemy of most finishes. Just a thought.

 

[pslamp32]

Not silicone but maybe a touch of dish soap as I did rinse things out a few times. I tried to get all the rinse water and soap but it is possible some trace amounts were left behind. If this is the problem I don't know what else to do really. Everyone says to clean water-base thoroughly but how do you do so without soap?

 

[Alan in Little Washington]

Get some gun cleaner from Binks or Graco. It is made to clean up after waterbased and oil based finishes.

 

[TracyP]

Could also be solvent pop, which is typically caused when the finish skins too fast for the solvents to be released. We find this quite often in automotive when the painter gets in too much of a hurry and buries the solvents in the finish. There is a lot of information on google as to the causes and cures.
Hope This Helps

 

[Travis Porter]

I use soap to clean my gun and haven't had any trouble. Did you clean the cap assemblies good and make sure none of the holes were blocked?

 

[FredP]

So my last few coats of sprayed polyacrylic (WB poly) introduced hundreds of tiny bubbles in my topcoat. This seems odd because I sprayed probably 15 coats before this using the same poly with no issues. Anybody have any idea what might be causing this. It seems that everytime I feel like I'm close something comes up to make me take a step backwards. This morning I sanded back to 220 to get rid of some scratches I didn't see. Everything was nearly perfect 3 days ago, yet in my quest to find perfection, I keep making it worse! Frustrating to say the least. :tinysmile_cry_t: Thanks.

are you spraying in a controled environment? temperature and humidity may have an effect. I dont use much waterborn finish so its just a guess.:eusa_thin

fred

 

[Howard Acheson]

Am I to understand that you have 15 coats on one project? If so, what are you trying to accomplish?

 

[pslamp32]

LOL. I'm trying to fill in the pores I guess.

 

[Howard Acheson]

That many coats of some waterborne finishes can be problematic. Most folks believe that the finish is "dry" when it no longer wet. However, when the water evaporates, the real curing process begins. Once the water has evaporated it allows other chemicals to come into contact and sort of melting (called coalescing) occurs and spreads out into a film. The film continues to cure and harden over a couple of weeks and it off-gases as it cures.

As many coats as you applied will have effectively inhibited this curing process and you may have continuing problems. The continuing off-gasing may be what are creating your problems.

If you want to fill the pores or grain of a wood, use a pore or grain filler. The job will be done in a day and you will end up with a much nicer job.

 

[pslamp32]

Yes sir, I know this now. Too late at this point. All in all it looks decent to the untrained eye. I'll probably start rubbing out tomorrow. We'll see how it goes. Another lesson learned! Thanks. :BangHead:

 

[John Reeves]

What did you sand it with? Norton claims that its sterated product will not leave anything on the surface but I have had the same problem too many times with many different finishes. Remember that the anti-load product that the abrasive manufacturers can do the same thing to what you are sanding or rubbing thus the lack of adhesion and surface tension of the finish wins the tug of war.

BTW, even the Klingspore product makes the same claim but I just purchased non sterated product. I am spraying Target coatings 8800 underlayment that I have in black today with my new ASTURO gun. I will let you know

(How do you spell sterated?)