I am refinishing a water-damaged veneered table. I removed the previous finish (probably a lacquer) with a commercial stripper. I washed the surface with PPG wax and grease remover. I repaired the veneer and sanded the surface. I applied a coat of exterior spar polyeurethane. All these products I have used before without a problem.
The polyeurethane pulled up into ridges about the width of a few brush-hairs, more or less in the direction of the brush strokes. It dried in this state. I sanded it smooth and tried again, with the same effect. I washed it off.
What is going on? How do I stop it?
The polyeurethane is probably about five years old, but appears fine. The brush was cheap hog’s hair. The stripper is the nasty stuff intended for stripping cars. I have used all of these in exactly this way to refinish car wood-work without a problem.
Help!
Replies
I had a similar thing happen once and thought I had contamination from silicone (from polish that wasn't fully removed when I stripped the old lacquer). But I also stained the wood, so I figured the stain hadn't dried or cured or whatever fully before I did the topcoat. But, although the crawling of the varnish sounds similar, I can't see how you could have contaminants after your prep work. I guess mainly I'm responding to keep your post "fresh" until a more knowledgeable person comes along!
Does the stripper or grease remover need to be neutralized before topcoating? If there is silicone contamination, a fisheye reducer may help--but I hesitate to suggest it because as I understand it, the reducer has more silicone in it to help the varnish bond to what's already there. If you don't have silicone contamination, seems like such a product could just make things worse.
Thanks, people. I will try many of the above. This morning I am inclined to try clearcoat (as in basecoat-clearcoat). I have used that on lots of automotive woodwork and have never had a problem. Of course, if it is silicone contamination, that will affect the clearcoat also. I will do my best to decontaminate it as you suggest.
You have listed a number of possible reasons for failure.
First, you may not have gotten all the stripper off and the residual is causing contamination. You may also have contamination from household "polishing cleaners" like Pledge that contain silicone.
I would also question using 5 year old finish. None of today's oil based finishes last that long without deteriorating. Finish is inexpensive in the overall cost of a project and fresh finish should always be used.
Likewise, using a better brush will almost always give better results.
Finally, while not a contributor directly to your problem, something like a spar varnish is not a good choice for furniture. Spar varnish is a specialty varnish intended for use on sailboats wood masts (spars) and is very soft and flexible so it can stay adhered to a flexing substrate. It is not a good choice for a surface that will have abrasion and objects placed on it. The best varnish product for indoor furniture is a good interior varnish or poly varnish. It will give a harder and more durable finish.
I would recommend stripping the finish off using a woodworking paint stripper containing methylene chloride. Follow the directions. Then, to deal with the possible contamination, wipe the surface with lacquer thinner using a paper towels and changing the face of the towels frequently. Do it twice. Now, apply a coat of Zinsser's Sealcoat which is a dewaxed shellac. This will seal in any remaining contaminate. Dewaxed shellac is required if you will be using a polyurethane varnish topcoat. Without sanding, apply at least two coats of your final finish. Then you can sand without risking going through to the contaminated layer.
This should get you home free.
I pretty much agreee with Howie, except that contamination usually causes fisheye. I've been thinking about the wrinkles, and the only cause I can think of is bad varnish, or perhaps incorrect thinner if you used any. Usually wrinkles occur because of unbalanced release of solvents, but my memory isn't good enough to be real specific about it.
Like Howie, I would have tossed anything that old. Agree about spar varnish being a poor choice for furniture, too.
Michael R.
I agree with Howie particularly on the probability that all the stripper was not removed. Need to use a LOT of mineral spirits to get all vestiges of stripper and the wax it contains.
Use fresh varnish--maybe wiping it on instead of brushing.Gretchen
I like to clean my surfaces from the stripper with Naptha. It works a little better than Mineral Spirits IMHO.
I have never had a problem when using Naptha, I have had similar problems like yours when I didn't clean off the surface.
Also, throw that can away and buy a new one. Finish is inexpensive and it is going to save you a headache.
Cheers!
Dark Magneto
As we speak I have decontaminated the surface with PPG wax and grease remover (sorry - I don't want to use naptha or lacquer thinner - too aggressive; it will dissolve the various fillers I have used). I have applied a coat of sealer, and when it is dry I will apply two coats of (new, furniture grade) polyeurethane. I have tossed the spar varnish.I originally used the spar varnish for the woodwork in a Lagonda convertible, for which it was perfect. The woodwork flexes as the chassis flexes, and it is exposed to rain and UV if you forget to put up the top. It color sands and compounds nicely. However, I am sure you are right that it is not as hard and abrasion resistant as a regular poly. The wood in a car does not get much abrasion. Even a closed car gets a certain amount of UV on the door cappings, and conversion varnishes I have used in the past do not hold up.
Well, I am sorry to say that the first coat of poly had little fish eyes all over it. I removed it. I am going to remove the sealer, use naptha, and then apply two or three coats of sealer and try again.
Fisheye is a different problem than wrinkling. It is due to contamination, usually by silicone residue from furniture polish that has soaked into the pores in the wood. There are several ways to deal with this. The three basic approaches are removal, barrier coats, and reducing the surface tension to more closely match the surface energy of the substrate, usually by adding silicone to the finish.
Cleaning: The problem with cleaning is that you can remove the surface silicone with ammonia or maybe TSP, you won't get it out of the pores, and as soon as a solvent hits the surface, more silicone will start coming out of the pores and contaminate the surface again. Nonetheless, I find it helpful to get as much silicone off as I can. Ammonia cleaners seem to work well, as should TSP. If you use solvent cleaners formulated to remove silicones, it it very important to change surfaces on your rag for each wipe, or else you end up just spreading the stuff around.
Once you have it as clean as you can get, you can try to isolate the wood from the rest of the finish with a barrier coat. Shellac works best for this, but if you brush it on, you risk pulling contamination up into the barrier coat. For this reason, I prefer to spray. Shellac is fine under lacquer or regular (alkyd) varnish, but is specifically not recommended under poly because of its poor adhesion. However, I am given to understand that de-waxed shellac works OK. Another option is to spray enough "dry" coats of the topcoat to form a barrier. With a dry coat you don't apply enough material to let the finish crawl, and multiple coats can build an effective barrier. I do this a lot with lacquers when there is mild contamination, but you have to be careful to get the coats to consolidate when topcoating.
Adding silicone products like Smoothie or fisheye remover to the finish also works, especially if you have taken pains to clean the surface to make surface tension uniform. Don't worry about contaminating your equipment, It's never been a problem for me, and I used to go back and forth all the time when I was refinishing.
This is one of those voodoo subjects, and everyone seems to have a different take on it. This is what I have learned in 30 years of finishing, but it certainly isn't all there is to know.
Michael R.
Thanks again. I was wondering if I have two problems, not one. I am sure I have surface contamination, but the sealer should have solved that. I am using a high gloss topcoat, and I did not use a filler. Some areas of the veneer have rough grain, and those were the areas that had what looked like fisheye. As the topcoat went on, tiny airbubbles were trapped in this grain, and that is where the eyes developed. I wonder if this is a surface tension phenomenon, but this time caused by surface irregularities. This AM I will scrub with naptha, fill, spray on the sealer, and spray the topcoat. I am getting sick of this.
Lum,
It is a surface tension problem. That's what silicone does to a wet finish-messes with its surface tension. It's possible that your initial sealer coat absorbed enough to affect subsequent coats. I've read that a brushed on coat will react with ridges instead of fisheyes (contamination following brushstrokes), but have not experienced this myself.
Other than fisheye destroyer as an additive, shellac is supposed to seal the contaminant in, but if you brush, it is likely to be pulled up into the shellac by the brush bristles. Best to spray. I've bought shellac in aerosol before, if you don't have a sprayer.
As mentioned by another poster, spraying light coats, too thin to be able to crawl, may work if the contamination isn't too bad. Spray several coats, then follow with a heavier one. (Not TOO heavy tho!)
Good luck,
Ray
That explains the ridges in the initial application. Interesting. The filler is drying as we speak. I will spray the shellac and try again tomorrow, with a fisheye eliminator. Starting with a mist coat.
This forum post is now archived. Commenting has been disabled