Cleaning Off White Dusted Surfaces Caused by Over-Catalyzed Conversion Varnish
Advice on cleaning off finished surfaces that are experiencing white dust from overcatalyzation. September 8, 2014
Question
I asked this before, but I'm hoping new eyes will see and help. We did two big projects last year, both clear conversion varnish without stain. Both jobs got covered with white dust all over. We wipe down with Windex, but the dust returned after two to three months. This has been going on for over a year. I assume both were over catalyzed. I was thinking that wiping with Windex may be causing static electricity with the friction, so I will try Endust, which I heard that it has anti-static properties. Any help will be greatly appreciated.
Forum Responses
(Finishing Forum)
From contributor A:
I believe Endust has silicone in it. Not a good idea if someone ever has re-finish.
From the original questioner:
I always thought Endust did not contain silicone, and the way it behaves compared to Pledge (no slick residue) I still think it does not. I just did a Google search and some say it does, but most say it does not. I'm still in the does not way of thinking.
From Contributor B:
Wipe them down with alcohol, which should relieve the static charge. If the dust still returns, you have a greater problem than static charge.
From contributor T:
Are you saying white dust but meaning haze instead? If not, then sometimes you have to call it what it is - dust. Every three months or so a flat surface will gather dust and have to be wiped. The way this thread reads, it sounds like you are going to the client's location to clean their cabinetry. You think the finish is over-catalyzed because it gets dusty every three months?
From the original questioner:
The issue is literally a white dust appearing on the surface. This is not a hazy or cloudy finish. When clean the finish looks bright and clear, then after two to three months the surface gets a white dusty covering. I was told that if CV is over-catalyzed, then the catalyst works its way out through the coating. I have been hoping that it will stop one day, but I just checked my records and one job was finished two years ago and it’s getting the dust on a regular basis. The idea of using Endust came to me because I read on the can that it contains an anti-static property. I thought the friction from wiping may be causing static electricity. I'm stuck, and don't know what else to do or try.
From contributor F:
If you have catalyst leaching to the surface of your finish because of over-catalization then you should wash it down with one part baking soda and nine parts water. That will neutralize the acid but if it is in a powder form than I'm not sure what it could be.
From contributor O:
Your client wouldn't happen to be using an ultrasonic humidifier? I can't explain the chemistry but some do generate a lot of white dust over two or three months use.
From Paul Snyder, forum technical advisor::
The problem you're describing is not caused by over-catalyzation. The amino resins in conversion varnish are catalyzed with a strong acid, typically p-toluenesulfonic acid (pTSA). Using too much catalyst does cause some problems though. The easiest way to spot a CV that’s been over-catalyzed is by the smell. The additional catalyst causes a reaction that forms butyric acid which smells like cat urine.
The problem you’re describing sounds like bloom. Bloom is a surface haze that develops over time and can be removed with a solvent wipe. The haze is caused by something exuding through the coating to the surface of the film. The exudate is often a component of the coating such as a plasticizer, cross-linker or other additive that did not react in. With acid cured coatings, a strong candidate for the source of the problem a sanding sealer that contains zinc stearate - the acid reacts with the zinc.
From the original questioner:
Answers to some of the questions: I've had my rep look, and he questioned my finisher and discovered he was over-catalyzing because he was trying to reuse yesterday's mix, and re catalyzed the next day. We are in California. We use a local company's conversion varnish, no sanding sealer. We self-seal with CV. This happened on two jobs only. Paul, there was no funny smell. When you say solvent wipe, what solvent?
From Paul Snyder, forum technical advisor::
What is the pot life of the CV you are using?
From the original questioner:
Pot life is 12 to 14 hours. Again, what solvent to use to wipe the cabinets?
From Paul Snyder, forum technical advisor::
You already gave it a solvent wipe - using Windex. I looked up the ingredients for Windex Original glass cleaner and it contains water, alcohol, and some cleaning agents. So, simple polar solvents (water and iso alcohol) and some cleaning agents are all you need to remove the contaminate you have.
Typically the next step would be to wipe the exudate from the surface, seal the towel in a bag, and send it to a lab to have it tested to find out what is. Wiping it off the surface doesn't stop it from coming back. It will continue as long as some of the ingredient that is migrating out of the finish is still there. The fact that the finish was past its pot life when it was used would be my biggest concern. Most of the durability will be missing and the extra acid will only serve to weaken the coating further. What's your plan to remedy the situation?
From contributor F:
It is not an uncommon practice to reuse yesterday’s product if it was handled properly for overnight storage. If you add an equal amount of what is leftover and let it sit for the next day, you can then catalyze what is required plus a little extra for the old material. This is done with many conversion varnishes but may not work with every ones.
From Paul Snyder, forum technical advisor::
Sherwin Williams recommends diluting the catalyzed left-over with three-four times un-catalyzed CV. Then the next day you only add enough catalyst for the amount of finish you added. You can also refrigerate the CV to extend its pot life.
From the original questioner:
Paul, that's exactly what we were doing, except my finisher screwed up on these two jobs - he took left over material from the day before, added new CV the next day and catalyzed for the entire amount, not just the new.
From Contributor D:
Endust has no silicone in it. It does have petroleum distillates in it, unlike Guardsman. Guardsman has no silicone and no petroleum distillates in it. Pledge has silicone, wax, and petroleum distillates.
