I have a problem with my Minwax Polycrylic finish - Woodworking Talk - Woodworkers Forum
 
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post #1 of 8 Old 10-05-2019, 06:10 PM Thread Starter
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I have a problem with my Minwax Polycrylic finish

Hi everyone, I have been lurking here for awhile to try and find a answer to my specific issue, but I couldn't really get a good feel for what I am doing wrong so I thought I would make a post to try and ask the experts here for help. First let me say I am in no way a expert, I know enough to get by but thats about it.. so any help would be really appreciated.. OK here goes..

My hobby is restoring old pinball machines from the 60s and 70s. My process is to strip them to bare wood then sand, bondo, sand more, etc etc till smooth, then prime, paint base coat, add a coat of polycrylic, then stencil first color, then polycrylic again, then stencil second color then polycrylic to finish up.

The reason why I lay polycrylic after the base coat and then between stencil colors is that the paint I use is a flat paint and I have found that the stencils do not adhere to the flat very well if at all. Its like trying to make a piece of tape stick to sand paper. So if it wont stick very well I will get runs and not very sharp edges in the stencils. So by adding a base of Minwax semi gloss polycrylic over the base paint, the stencils will have something to stick to. I have had good success with this method for awhile now, however the last cabinet I just restored had issues. after painting my first color stencil, the stencil tack (as I would pull it up) would pull up the polycrylic with it. For some reason my polycrylic would not adhere to the cabinet at all in certain areas. I should say that the stencils I use are a vinyl type stencil with a low tack on the underside.

So this is the first cabinet that has had this issue. The paint I am using is a rattle can graffiti paint called 94. The reason why I use it is that the base coat white is a exact match to the original factory colors and they are of the low pressure variety so it really reduces the chance for runs and such.

So anyway... The only thing I have done differently with the polycrylic this time as opposed to previous times is that I used foam brushes this time to apply it. I am wondering if anyone thinks that maybe a foam brush might be the culprit here to my adhesion problems? Also At first I thought it might be the Minwax brand of Poly so I went and bought a better brand and I had the exact same issues. I really dont want to strip this cabinet again for a third time only to have the same issues arise. not to mention that the stencils are rather expensive and they are of a one time use only. So if anyone has any advice or would know why the polycrylic is not adhering to my base I would love to know. Thanks again for any help you can give..

PS.. for reference, this is the brand of paint I use.
https://www.sprayplanet.com/collecti...94-malta-white


T
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post #2 of 8 Old 10-05-2019, 11:58 PM
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I don't know about advice but I can relate my experience, of sorts.

I painted a router cabinet with a gloss latex, white. In a discussion with tech support at Minwax I was told that putting any polyurethane over the latex is not recommended. I am enclosing in quotes what I was told, "Some professionals have been known to use Polycrylic over latex." The router table has been relatively bullet proof and it has been at least 15 years.

I don't know how old you are but flat paints have changed since my childhood. (1940s and 1950s) Flat paint used to have a rough surface when dry and intended to make the top coat adhere better. Today flat paint is the same as gloss EXCEPT there are additives intended disperse the light reflected thereby giving the illusion of a flat paint surface. This is why flat, semi-gloss and egg shell paints must be stirred frequently to keep the additives in suspension.

Rich
Just a dumb old paper boy from Brooklyn, NY
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post #3 of 8 Old 10-06-2019, 06:08 PM Thread Starter
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tscottn

hi and thank you for the reply. Like I mentioned in my post, I have done a few cabinets using Poly over my pained surface with the exact same paint each time.. This is the first time I am having this issue which is kind of weird. The only thing I can even think of that may have been different about this application is the use of a foam brush instead of a bristle brush applicator. I wonder if the foam may introduce air into the poly as it is put on or something to this effect that would cause it to not adhere to the surface.

I understand what you mean about flat paints now a days instead of way back. It could be a combination of not enough grit and the foam as well.. I am going to try again using a bristle as my previous restores and see how it goes. Thanks for the info.

PS.. by the lack of replies I can only assume not any people have come across this issue..
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post #4 of 8 Old 10-07-2019, 12:30 AM
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Limited experience here, but Iíve had issues with reused foam brushes in the past that still has soap residue inside the brush head.

Also, maybe consider a light hand scuff on a test piece thatís painted and see how if it goes once you apply the polycrylic.


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post #5 of 8 Old 10-07-2019, 08:06 AM
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No personal experience, but a suggestion...

Probably stating the obvious here, but since the only difference is the brushes, you might try an experiment with a couple of pieces of scrap - one with foam brush, the other with bristle brush over the same base.

Jim

"I've learned the hard way that I can't afford to buy cheap tools"
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post #6 of 8 Old 10-07-2019, 10:05 AM
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Its obviously not adhering. To my knowledge PA requires sanding before and between coats.



If there is enough "grip" in the paint texture you may get away without sanding, in which case, I would give it a wipedown with DNA to remove any possible paint contaminants.



Maybe you've just gotten away with it so far?
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post #7 of 8 Old 10-07-2019, 06:00 PM
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A real pinball expert is Steve Young at The Pinball Resource. www.pbresource.com and he is a former partner of mine.

I prefer not stripping and re-sanding, but rather "touching up" the damaged areas. Steve not only has the expertise you are looking for, but he likely has all of the replacement parts that you will need to restore your pinball machines to new. If I had to do this, I think I would use a clear dewaxed shellac rather than polycrylic for all but the finish coat, and I would NOT use foam brushes. Some really good artist brushes would be my choice.

Contact Steve. I'm certain that he can help you. He is located in LaGrange, NY, which is near Poughkeepsie, NY, so East Coast Time Zone.

Charley

Last edited by CharleyL; 10-07-2019 at 06:06 PM.
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post #8 of 8 Old 10-07-2019, 06:27 PM Thread Starter
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Quote:
Originally Posted by CharleyL View Post
A real pinball expert is Steve Young at The Pinball Resource. www.pbresource.com and he is a former partner of mine.

I prefer not stripping and re-sanding, but rather "touching up" the damaged areas. Steve not only has the expertise you are looking for, but he likely has all of the replacement parts that you will need to restore your pinball machines to new. If I had to do this, I think I would use a clear dewaxed shellac rather than polycrylic for all but the finish coat, and I would NOT use foam brushes. Some really good artist brushes would be my choice.

Contact Steve. I'm certain that he can help you. He is located in LaGrange, NY, which is near Poughkeepsie, NY, so East Coast Time Zone.

Charley
I know Steve well.. been in the hobby for a long time .. just looking for some wood working expertise..
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