Polycrylic turns yellow over white paint

[ErnieM]

I had a new can of Minwax Polycrylic Satin and decided to try it on some scrap boards that I had painted off-white using Sherwin Williams Duration acrylic latex. A while back, I tried brushing the Polycrylic with less than satisfactory results, so I decided to try spraying it on. I sprayed it on some unfinished poplar and it went on smoothly and dried normally. Then I sprayed a coat onto the white painted wood. Again, it sprayed normally and dried to a rather pleasant satin sheen - just what I was hoping for. Unfortunately, the moment the Polycrylic hit the paint, it turned yellow. Not a tinge of yellow as you might expect from an oil based poly, but a real yellow. I did some searching on the internet and found that this is a problem that occurs frequently over white or off-white paint. I know that there are better products available to us (Target em6000 comes to mind) but I would love to understand why the Minwax Polycrylic acted this way. Any ideas?

 

[Endless Pursuit]

If you have anything else that's white, try putting some Poly over that. Some "off white" paints have yellow pigmentation and you might have liberated that out of the acrylic latex.

 

[ErnieM]

If you have anything else that's white, try putting some Poly over that. Some "off white" paints have yellow pigmentation and you might have liberated that out of the acrylic latex.

I'll try that but I don't think that's the cause. While the poly was still wet, I wiped some off with my finger and the wood underneath was the original off-white color. It appears it was the poly that turned yellow - not the painted wood underneath.

 

[Jeff]

but I would love to understand why the Minwax Polycrylic acted this way. Any ideas?

That's a tough nut to crack and you're not alone in the mystery.

I found a tidbit buried in this post. The OP used vinegar/water (1:10) and wiped it down to remove the yellow color so it appears to be a surface phenomenon. Maybe the yellowing is catalyzed by light reflected off of the underlying white surface. ???

http://funcycled.com/products/why-does-polycrylic-yellow/

1. Maybe try it with a wet rag or a Scotch-Brite ultra fine pad to clean the surface.

2. Let it dry. Respray the piece with Polycrylic. Does the surface yellowing reappear?

 

[ErnieM]

That's a tough nut to crack and you're not alone in the mystery.

I found a tidbit buried in this post. The OP used vinegar/water (1:10) and wiped it down to remove the yellow color so it appears to be a surface phenomenon. Maybe the yellowing is catalyzed by light reflected off of the underlying white surface. ???

http://funcycled.com/products/why-does-polycrylic-yellow/

1. Maybe try it with a wet rag or a Scotch-Brite ultra fine pad to clean the surface.

2. Let it dry. Respray the piece with Polycrylic. Does the surface yellowing reappear?

Jeff - I read the same article. Actually, you don't even need the vinegar - just wiping the wet finish with a wet rag removes the yellow polycrylic. The author said the piece retained its protective coating, but I doubt it. For the small piece I'm working on, I wanted to use the polycrylic to increase the sheen a little bit as the satin Duration paint was almost flat. The paint itself doesn't really need a topcoat for protection. In the end, I ended up spraying a single coat of oil based poly and all is fine. It would be nice to know what exactly caused the polycrylic to yellow, but that's a mystery that may never be solved.

 

[Howard Acheson]

Many manufacturers of waterborne clear finishes add an amber dye to their "clear" finish. This is done to mimic the color you get when you use an oil based clear finish. Oil based finishes contain linseed oil which will impart an amber cast when applied over a pure which waterborne finish. It used to be that a waterborne clear finish would overcoat a white without adding any amber. Many finishers wanted the amber color as it tends to highlight the grain in the wood.

If you want a totally clear finish, you will need to look around for a clear waterborne that contains no amber tint additive.

I also may be that the two finishes you are using are not compatable and an interaction between the two is causing the problem.

 

[Endless Pursuit]

Must be a mild amine blush.

 

[ErnieM]

Many manufacturers of waterborne clear finishes add an amber dye to their "clear" finish. This is done to mimic the color you get when you use an oil based clear finish. Oil based finishes contain linseed oil which will impart an amber cast when applied over a pure which waterborne finish. It used to be that a waterborne clear finish would overcoat a white without adding any amber. Many finishers wanted the amber color as it tends to highlight the grain in the wood.

If you want a totally clear finish, you will need to look around for a clear waterborne that contains no amber tint additive.

I also may be that the two finishes you are using are not compatable and an interaction between the two is causing the problem.

Howard - I'm thinking that incompatable finishes might be the answer. I'm very familiar with the yellow tinting that happens with oil based finishes over light wood. That's not what happened here. This yellowing wasn't a tint - it was a full blown and immediate color change. I'm sorry I didn't think to take a picture of it. When I get a little time, I'll try to duplicate the problem and photograph it.

 

[CrealBilly]

Could it be you applied poly(a)crylic over acrylic paint? the poly(a)crylic may have interacted with the acrylic paint.

Just kidding... try dabbing a little rubbing alcohol over the paint see if it yellows. Minwax polycrylic does contain 5% Isoporpanol (rubbing alcohol) and I suspect that may have caused your yellowing.

 

[ErnieM]

Could it be you applied poly(a)crylic over acrylic paint? the poly(a)crylic may have interacted with the acrylic paint.

Just kidding... try dabbing a little rubbing alcohol over the paint see if it yellows. Minwax polycrylic does contain 5% Isoporpanol (rubbing alcohol) and I suspect that may have caused your yellowing.

Just tried it Jeff - alcohol had no effect whatsoever. I guess it's the other 95% that's causing the problem.

 

[SubGuy]

I just don't use Minwax....They burned that bridge with me a long time ago.

 

[Jeff]

Jeff, I read the same article. Actually, you don't even need the vinegar - just wiping the wet finish with a wet rag removes the yellow polycrylic.

...and presumably the rest of the polycrylic too. :dontknow:

In the end, I ended up spraying a single coat of oil based poly and all is fine.

A good solution to a perplexing problem. ccasion1

So the oil based poly over the white base is not amber?

 

[ErnieM]

...and presumably the rest of the polycrylic too. :dontknow:



A good solution to a perplexing problem. ccasion1

So the oil based poly over the white base is not amber?

Yes, if you put enough oil based poly on light woods you will see an amber tint. I only sprayed a single coat and it's fine. The polycrylic didn't give the paint a tint - it actually changed the color significantly and immediately. I'm curious to know if this is a problem unique to Minwax Polycrylic or will any similar water based product cause the yellowing.