Coping with an Anti-Silicone Snafu
How to clean up and start over when anti-silicone additives make an orange-peel problem worse. June 28, 2006
Question
I had a problem while working with opaques in the base coat. I saw here and there a silicone contamination on a mahogany interior door. I put anti-crater product on the top coat of 25% shine (anti-silicone material on opaque 25%) and when I sprayed it, the drying top coat got to be wavy as an orange peel. It is as if you sprayed the finish with not enough air. I thought that maybe it was the viscosity of the material or that I did not spray well, so I did another coat with the anti-silicone and this time it was a real catastrophe. I called the distributor and he came and checked and tried the spray in my booth. He told me he believed me, and afterwards he said that the two products should not be mixed. I called the company in Italy and asked them what and why. They said that the distributor sold me two products from two different companies and I should sand to the wood and begin the finish from the beginning. Any suggestions how can I do the finish without going to the beginning?
Forum Responses
(Finishing Forum)
From contributor A:
The best thing to do is to clean off the surface and start over. I think you will save time, and you will end up with a better job. It’s hard, and a lot more work to make a bad job look good.
From contributor B:
This is one of the reasons our shop only uses products from one company (ML Campbell in our case but I don't know if it's available where you are located if you're not in Uncle Sam's backyard). I've had this problem, often called "fish-eye" while refinishing the occasional item for a customer. We rarely do refinish jobs specifically for this reason. I have to add a product that ML Campbell makes called "Fish Eye Eliminator". One squirt to a quart of finish does the trick. Use it in every coat. It seems to cause the lacquer to cure more slowly.
From the original questioner:
We take money from Uncle Sam but don’t buy stuff from him. I am in Israel - we have European stuff, some from Italy. I will try something, I am doing a test piece and I will check it out.
From contributor D:
If you do sand you should wash your surface with TSP (tri-sodium phosphate) and water. If TSP is not available for you then spray the surfaces with a water mix of dissolved oxalic acid. Use a garden bug spraying container or a deck sprayer to spray this. This then needs to be rinsed off, preferably using a pressure washer set at between 500 psi - 700 psi. This pressure is enough to rinse the product off the wood without the water soaking into the wood too much (if at all) and also without so much pressure that the high pressure stream destroys the wood.
That gets rid of most of the source of silicones and contamination. Then I would spray on a thinned coat of dewaxed shellac just to make sure that everything is sealed in. The thin shellac coating will be your barrier coat. Scuff lightly with 320 on that and continue as normal. If none of those chemicals are available to you then a good washing and rinsing of the surface with xylene will help. Then do the shellac barrier coat (light applications to seal in the contamination and not have it float to your surface).
From the original questioner:
Thank you all. I have a piece I am testing.
From contributor E:
If you can get the current finish to sand flat you can use shellac as a separation coat to seal what is already on the table. Then you can spray several very light coats of finish. Let them dry for extra time between coats and then finish, but don’t get any of the following coats too thick in one spraying or you could be back to square one.
From the original questioner:
I did a test today, because the silicone is on the topcoat only from an anti-silicone material I added. So I did a test on a sample piece. I did dilute my base coat 1:6 to thinner and sprayed it in light coats, and for 5-6 times while waiting in between to dry, and then scuff sanded it and sprayed a real good coat of the base coat and then sand and topcoat and it got out good. I will check it out on the big door and hope it will be ok.
