Clear-Coat Yellowing Problem in Cabinet Interiors

      Many oil-based clear-coats turn yellow when kept in the dark. The severity may depend on the type of oil used. Here's a case example, with comments from the pros. February 12, 2007

Question
Just finished a large job and having big problems on site. Clear maple and birch, sprayed with water borne, oil modified, acrylic fortified, cross linking polyurethane satin finish. I used $13000.00 of product for this job. All cabinet and millwork is installed and the building is ready for testing, but all my cabinets are discoloring inside (yellow) where the light doesn't hit. The outside of cabinets and doors have nice clear finish, slightly amber because the oil modified over time, the supplier says. But when you open the cabinet, it's bright yellow - not nice, and not passing code. The owner and chemist came down to site and are puzzled. What was missed in the making of this product or what can fix it?

Forum Responses
(Finishing Forum)
From contributor W:
You're saying that the owner of the product manufacturing plant and the chemist are puzzled? How many coats were applied to inside where it is yellowing?



From contributor S:
Oil-based coatings yellow more in the dark than in the light. Traditional linoleum manufacturers, such as Marmoleum, recommend that you move objects around regularly to prevent yellow patches developing on pale coloured lino. As to how to prevent it happening in a cupboard, I can't say, other than use a non-oil coating.


From contributor J:
The manufacturers of the raw resin used in oil modified urethanes (waterborne) rarely disclose the identity of the oil used in the manufacture of their resins. As contributor S said, many drying oils (linseed being the worst culprit) yellow more in the absence of light. The chemist from the coatings company (if he is indeed a chemist) should know that, as it is general knowledge found in all coatings manuals.

Oil based alkyds have been known to do this for decades. Unfortunately, I know of no solution for you other than to remove the finish or paint over it. Just curious, though - is the finish touted as being "water-clear and non-yellowing"? If so, you have a case against the manufacturer of the finish.



From contributor W:
You can't get any better advice than from the above two... it's now how, if possible, to correct what's there, without stripping which will be a disaster. The old timers in painting used a method for controlling the yellowing on oil based white paint. And that is add a little white tint to the clear coat and apply that on top of white paint. I don't know if that could be done here or not. I think it would be worth a try to see what it would look like instead of redoing the whole thing... Just my opinion... 'cause stripping isn't any fun. Been there, done that.


From the original questioner:
2 coats on the inside of door and cabinet and 3 on the finish edges and door front. The product says it's slightly amber, but this is day and night yellow and clear. The resin supplier came down to the site today, and another technical rep, and I got the same reply. This product can not be stacked. When 2 doors are put on top of each other, the 2 faces that are together go bright yellow. Even months later. All reps have said something went wrong with the chemicals or the mixture.


From contributor G:
I was in a similar situation a number of years ago. I worked for a distributor for a major industrial coatings manufacturer and we sent pail after pail of the wrong color (salesman's error) to a job, and then we paid for the job to be redone in the correct color using a competitor's product. The point of this story is that the coatings supplier/manufacturer has to make good on this one.


From contributor B:
I had the exact same thing happen to me on a kitchen paint job. I used Sherwin Williams Water White lacquer over a light colored lacquer paint. It yellowed on the inside of all the cabs and around the door edges where the light does not get to. SW refused to help in any way and I ended up repainting the whole kitchen, this time with no clear coat.


From contributor I:
I have almost 20 years of finishing, and it's a bad batch. Whoever was making that batch missed something or didn't put in enough of something. The manufacturer needs to make good.


From contributor R:
It's quite common for a coating to yellow in an interior situation faster than an exterior application. Blame it on the type of oil being used, most likely a soy oil. Years ago my friend who owned the original US Cellulose company in San Jose California advised me to add just a hair of white UTC to my coating, even if I was doing a clear coat finish. This would help cut down the yellowing a bit, but... the yellowing of a coating was inevitable.

Water based coatings can leave a blue or green or yellow cast once they dry, which is one reason I won't use them. Even the metals in the water can affect the color of the coating once it's dry. Here in California they decided to add ammonia to the water and we all know what ammonia does to wood. How long had your cabinets been finished and installed before they had the grand opening?



From contributor O:
I suspect the questioner has heard all she wants to. "The coating was bad." Period, call the lawyer.

There is so much information that we do not have to come to any conclusions. I will say that for $13,000 of business, you should be getting answers. That's approximately 500 gallons! Was that all made and delivered in one batch?

I'm still curious about the time lapse before the discoloring was noticed. Also, has anyone tried to replicate this or can it not be made to happen again? The description you give for the coating makes me think that it is a "higher end" formulation. Why would the manufacturer choose to use a third rate resin on a cabinet job of this nature when the yellowing issue is common knowledge? If they are that irresponsible, why did you choose them to provide your coatings anyway? Didn't you make some samples? Have they yellowed too? There must be more to this story.



From the original questioner:
The company is pretty new, about 8 years old, but so is LEED in Canada. So we are learning together. And yes, samples were done, but they have always been in the light. We did notice same yellow in the shop when stacking the doors, but this wasn't brought to my attention until now. The owner has called me to say they can and will fix the problem with ultraviolet lights on the job site. They will be there for a few days moving the light around. We will see, but it is in their hands now. I will have to say we all learn, and I did research the new product, just not enough, and I used what is signed off and given to me. I wish I did have more control on what is used or chosen. But the customer service is great, was great, and the company is working hard to fix their problem. Thanks for all the replies.

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