Refinishing contamination problem
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Is contamination at fault for the appearance of fisheye when refinishing furniture? August 29, 2001
Question
Sometimes when we strip and refinish a piece of furniture, we run into a contamination problem. Usually the problem shows up in the top surface. I am assuming that is because the top of the piece was cleaned with a polish. Especially on deep grain woods like oak, the contamination shows up in alligatoring, crawling and fisheye, sometimes to the point that it almost looks like you put stripper on it. We used a chemical stripper to get the old finish off and followed it with a thorough cleaning with lacquer thinner, which usually seems to get the job done. We let the piece sit a couple of days to flash off and yet we still have the problem. I have used fisheye eliminator in the past and don't want to go that route again, as it contaminates everything. How can we get rid of this problem?
Forum Responses
We don't do much refinishing, but we have had the same problem. The only solution we have found is to wash the top down with naptha or Prep-sol, let it dry and then stain. The only way we have found to get the topcoat to go on well (we use cv) is to use smoothie fisheye eliminator. I know it contaminates the whole system, but thinner seems to clean it out with no problem. Just don't save the thinner you used to clean out your system.
I use a product called Purge All as a wash after stripping. It's a powder concentrate that you mix with water. It has worked well for me by removing all sources of possible silicone contamination. It's available at Hood Products.
From contributor J:
Xylol works a little better then naptha. I have used an automotive wax and grease remover made by Krona that works okay, but still had to use fisheye eliminator. I get this still called "glossy" that comes in a little 4 or 8 ounce bottle, I think. Only have to use it on projects I refinish at home.
It would be best to sand and finish in a different area to keep from cross contaminating everything. I used to work for a dining room furniture company that made solid oak tables and chairs. I hated it when they would run returned tops through the polisher to remove the old conversion varnish, as the sanding dust loaded with contamination would mess up my whole line. I have never had any success completely removing all contamination and refinishing without using a fisheye eliminator.
Fisheye is caused by silicone contamination and to eliminate it on re-spraying, if you suspect it's there, add smoothie (fisheye eliminator). This is nothing but silicone in itself and once you start using it in your guns, you'll probably have to keep using it. What's been happening is, after you strip old finish off, the proper cleaning of wood is not accomplished to completely remove the contamination of old finish and stripper. As suggested, a product like Purge All would help. But after this cleaning and before a new finish is applied, a light coat of shellac is recommended to cover any possible contamination still there. Then proceed with your new finish.
What topcoat are you using? NC, CV, water based?
Doesn't matter! They all do it when the pore is full of silicone.
From the original questioner:
We are using MLC Magnalac Precat. But it's true--it doesn't matter. In the past, it has happened with any finish. The problem becomes how to get rid of the silicone. We stripped these pieces again, cleaned them with lacquer thinner followed by acetone, and finally alcohol and then washed them again with TSP and a clean water rinse. We then applied a paste filler coat to close up some of the open grain. We are letting it sit a couple of days over the weekend and then we are going to stain and refinish. I will let you all know how it turns out.
SW makes a solvent specifically formulated to be used prior to refinishing. It will remove silicone. R7K156
In the future, try doing your washing before stripping. Wipe down with naptha and a scotch brite pad, dry with a clean cotton cloth. Get some new clean naptha in a clean can and a clean rag and wipe down again. This will help to get some of the silicone, wax, dirt and other contaminants off before you strip and wash them into the grain. Part of the problem also is the wax in the stripper--it can cause areas that don't want to dry. I usually take a cloth dampened with water and very lightly wipe the wet areas. I don't know why but it dries after doing this. I also agree with the smoothie--I hate to use it myself but if I am doing a strip and refinish I always add it to my topcoat. (Vinyl sealer also helps.)
From the original questioner:
We finally got our courage up and started putting the finish on. We started out with 3 very light coats of vinyl sealer (Sherwin Williams brand). There was some roughness because of putting the coats on so light. So we block sanded down as far as we dared to go without lightening the stain to get the surface as flat as possible. Then we started with a light pass with the Magnalac and let it flash for a moment or two to see how it was going to react. It did not seem to start crawling so we came back across it with another heavier pass. Still all was going well so we let that fully dry and came back with one full wet coat and that seemed to do the trick. I think the vinyl sealer was the answer, as it did not seem to crawl when applied with a light coat and it seemed to block out the problem that was coming through to the topcoat. The final finish was not as perfect as I like it to be, but was probably about 95% of our normal finish...plenty good enough to call a fine furniture finish.
I hate to rain on your parade but I had the exact same situation a year ago. I was doing a bunch of dresser tops from a hotel. Surely they use tons of Pledge and silicon was awful. I sprayed them all the same as you did and 4 months later they all came back with coat separation. Separation happened between vinyl sealer and wood surface. I was using Chemcraft vinyl sealer and Opticlear 60 (precut) as a topcoat. Hope MLC will bail you out of this mess.
From contributor J:
I don't want the above post to scare you. I have done this many times, and do it every time I refinish something in my shop at home. So far, so good. I use light to medium wet coats to keep the fisheye from showing. Sand level like you mentioned. Then topcoat the same way. With the addition of silicone in my sealer and topcoat as well as extra reducer and retarder. Have done this with N/C lacquer, with or without vinyl under it, post cat lacquer, as well as C/V. No separation that I know of.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
From contributor A:
You are making this too difficult. Just wash the furniture with mineral spirits and wipe with paper towel. Do this a few times. Mineral spirits do not neutralize silicone - they disolve it and must be removed with paper towels. If anyone ever sprays WD-40 in your shop, they must be banned forever. One small squirt of WD-40 can give you years of fisheye games. It is a good practice to alway wash with mineral spirits after stripping. It will also remove the wax left by the stripper.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
WD-40 does not contain silicone. That is an Urban myth. MSDS has to list silicone (it's a hazardous ingredient), so check the MSDS.
Comment from contributor B:
Beware of wiping with paper towels - some brands have silicone in them. Bounty is said to be a safe choice.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor D:
A popular book on finishing gives four alternative solutions. The one I've chosen is working so far. Isolate the silicone that got into the wood with a coat of sprayed shellac, then continue to add coats from there. If you suspect silicone contamination before you start, just spray the shellac coat over the entire surface. I only found out about the contamination too late, so I scraped off the "crawling" finish, sprayed only in the area of the damage, and added new coats on top of that.
By the way, my surface got contaminated because I used an oil stone to prepare my scraper. I didn't wipe off all the oil from the scraper and very efficiently jammed streaks of oil into the wood!
