Fish Eyes in my Lacquer?

[Jason Tuinstra]

This may be rather obvious, but please bear the old boy...

The last couple of times I've sprayed lacquer, I've notice the appearance of fish-eyes, not everywhere, just in certain spots. They didn't appear right away. Usually after the first coat. I never had this before and I couldn't (can't?) figure out what the problem is. I'm very careful not to contaminate the wood because I know this can cause problems.

I think I figured out what my problem is. My question is, am I in the ball park? I just started wet sanding after the first coat with "Silicon Carbide Sandpaper" using Naphtha to lubricate the paper. I know silicon is what causes fish-eye's. Is it the residue from the sandpaper that's causing me my grief? It would seem to make sense to me. What do ya' think? Any help would go a long way in maintaining my sanity.

Jason

[Bruce Page]

Jason, it sounds like you do have a contamination issue but I don’t think the wet/dry paper is the culprit, refinishers & the auto industry have been using it for decades. I think (but I’m not positive) that cold temps can cause fisheyes.

[Jason Tuinstra]

Bruce, I guess that is a problem with my little theory. Wet/dry sand paper is for finishing. I usually spary in a heated garage, but I open the door between coats to let out the fumes. Perhaps I don't let the garage heat up enough between coats?

Thanks for the advice.

[Dale Thompson]

Jason,
I would suggest that you are correct in blaming the silicone carbide sandpaper. Silicone IS NOT compatible with many finishes, including certain paints. Some years ago, when I could still hold a job, we had a problem with "fish-eyes" on powder paint. Our plant had the potential for silicone "dust" floating around. The paint supplier said that they had a similar problem some months before. It turned out the the cleaning lady was using a siliconized spray to clean the door knobs into their test lab. YEP! The spray was eliminated and so were the "fish-eyes".

Whatever, my first step would be to change your sanding media. HEY! You never know. I might actually be RIGHT on something - don't hold your breath but hold the silicone.

Good Luck! "Fish-eyes" are a pain in the neck.

Dale T.

[Jim Becker]

Perhaps I'm mistaken, but silicon and silicone are different things...the former being part of the mineral content of the abrasive. The latter is a chemical compound but I'm not so sure they are related. Perhaps there is a chemist umongst us??

[Todd Burch]

I talked to one of my suppliers the other day on just this topic. His answer (30 years in the biz) was that you can't get fisheyes from silicon carbide sandpaper.

Jason, are you getting raised bubbles or lacquer-free craters? The latter are fisheyes, the former being a problem with open pored woods, like oak, mahogany, etc, and having the finish too thick and allowing it to dry too fast. Have you tried any retarder or extra thinning? Are you getting any blushing?

As far as fisheyes, there is an additive called fisheye reducer, but I have never used it and won't. My recommendation would be to find the source of the problem - could be the rags you are using, could be hand prints after touching something that has silicone on it, like some car waxes, and car weatherstripping and other rubber items.

Also, when I used to paint cars, I wet sanded all the time, but have not with wood. Maybe your naptha is dirty? If I was concerned with dirt or grease or fingerprints/ whatever, when I painted cars, I would use a product called "Wax and Grease" remover (PPG - don't remember the product #), but it removes everything on the surface of a finish. (It's great to have on hand when you are detailing a car too - removes every bit of tar and road grime up around the rocker panels).

Hope you figure it out...

Todd.

[Dave Arbuckle]

Perhaps I'm mistaken, but silicon and silicone are different things...the former being part of the mineral content of the abrasive. The latter is a chemical compound but I'm not so sure they are related. Perhaps there is a chemist umongst us??

I'm not a Chemist, but confusing silicone and silicon is kind of a pet peeve with me.

Silicon is an element, symbol Si.
Silicone is a man-made compound, primary ingredient silica. Silica is SiO2.

Silicone is a cause of fisheye. Silicon is a large part of what integrated circuits and beach sand are made of.

Dave
(don't get me started on misspelling "rabbets" as rabbits... )

[Dan Smith]

Well, I am a chemist and what Dave says is not quite correct.

Silicon is an element Si, but is not found free in nature. It is in chiefly the form of the oxide as silica or silicates. Sand, quartz, rock cyrstal, ametheyst, agate, flint, jasper, and opal are a few in which the oxide appears. Granite, asbestos, feldspar, clay, mica are a few of the numerous silicate minerals. Silicon Carbide SiC is prepared commercially by heating Silica and Carbon in an electric funance using carbon electrodes.

Silicone in it's most basic form is (CH3)2 (Si-O)n where n=1-??

Silicone is a polymer of the di methyl silica shown above. Inadvertantly invented (did not know what he had) in the beginning of the 20th century by an English chemist Kipping, and in the late 1930s General Electrics in partnership with Corning chemists figured out how to use Kippings chemistry to make the first practicle silicones for high temperature insulating materials (that GE needed to make better light bulbs).

So from those came all the Silicone polymers which we use today from adhesives and lubricants, to breast implants and antifoams.


Sorry for the long winded explaination....

So to address the question, Maybe the paper could leave a residue, but probably not from the Silica Carbide, but more likely they use a silicone adhesive to hold the silica carbide to the paper, for which the naptha may act as a solvent.

taking lab coat off, putting flannel shirt back on...

-dan

[Kirk (KC) Constable]

I feel your pain. I've experienced this several times, and can find no explanation other than, 'sometimes it just happens'. I've gotten it at one end of a tabletop and not the other, and one table at 1:00 in the afternoon and one at 4:00, but not the one from 2:30.

Contaminants? Maybe. Use of a commercially prepared tack cloth? Maybe. Dust mites in the air? Maybe. Sandpaper? I don't think so...I use Klingspor stearated papers frequently.

I recently read that boo-boos can happen when the top dries too quickly and the gasses haven't all escaped from underneath...thus the pinholes as they do escape. This makes sense to me, but I don;t know how to 'apply' it to the process.

I spray in a dedicated room. In the summertime it's hot in there. In the wintertime (such as it is around here), we heat it up to 70 degrees or so to spray. The digital thermometer/humidity thingy tells me that I get the best results (lacquer) at around 75% humidity...and the temperature doesn't really matter. Perfect conditions seem to be around 80 degrees and 75%...but I've had fisheye/pinhole problems in all conditions.

Get the thinner out, strip it, and start over.

[Jason Tuinstra]

Hey guys, as always, great advice - and spell checkers (silicon/silicone doh!!! )! My problem is definitely fish-eyes. To solve it, I've striped the finish off and "dusted" a few coats on so that the fish-eyes don't have enough lacquer to pop out (Flexner recommends this as an option in his finishing book). It seems to have worked.

Also, I read that Fish-Eye reducer adds silicone to your finish so that it overcomes the contaminant by, essentially, making peace with the contaminant. I'd rather avoid that. I'm trying to get rid of silicone, not add it.

Anyway, I'll check my rags and heed the rest of your wealth of wisdom - along with printing out the chem. lessons for my homeschoolers

Thanks a ton.

Jason

[nic obie]

If all else fails, and sometimes it does, you can buy a bottle of 'Squirtz' (4 oz for $40) at most any automotive store that sells paint.

I just refinished a small table that was inlaid with hundreds of little pieces of wood. I figure over the years silicone from waxes got down into the cracks and I just couldn't wash it out. I tried shellac and misting on the first couple of coats, which always has worked in the past, but not this time. I still had fish-eye.

I about choked when the guy said $40, but it worked.

[Chris Padilla]

I heard pure lemon oil is about the best thing for cleaning/wiping wood surfaces. The folks who make Velvit Oil recommend it.

[Ted Harris]

This may be rather obvious, but please bear the old boy...

The last couple of times I've sprayed lacquer, I've notice the appearance of fish-eyes, not everywhere, just in certain spots. They didn't appear right away. Usually after the first coat. Jason

Jason,
Forget about it being from the sandpaper. Another thing, when wet sanding, just use a spray bottle of water with a little dish soap added in to help with the friction. After wet sanding, use lacquer thinner to clean the surface and let dry for about 15 minutes. Do not wipe too hard or too long, as the finish will begin to melt and suck the paper towel into it. Just wipe off really quick. Works great!
It is most likely solvent pop. This means that the finish is applied to thick, and dries to fast, thus not allowing the solvent to escape from the inside out, causing what looks similair to fisheyes. I had to deal with this problem a few years ago, and it was a nightmare.
Good luck!

[Phil Phelps]

I really don't care how it happens, cause it's been happening to me for decades. Buy yourself the fisheye eliminator from the automotive store, add a drop to the cup and your problems are over. Fisheyes pop up in all kinds of paints and lacquers from time to time. Use the eliminator and don't worry.

[Ted Harris]

I really don't care how it happens, cause it's been happening to me for decades. Buy yourself the fisheye eliminator from the automotive store, add a drop to the cup and your problems are over. Fisheyes pop up in all kinds of paints and lacquers from time to time. Use the eliminator and don't worry.

Fisheye and solvent pop are two entirely different problems, for two different reasons. Fisheye is caused by oil/silicon in the previous finish or contamination in current finish/apparatus. Solvent pop and fisheyes are commonly misdiagnosed as the same problem.
Solvent popping, or pinholes, appear when solvent evaporates so quickly from a wet film (paint) that the increasingly viscous liquid paint is unable to flow into the resulting void. Here are common causes of solvent popping:
temperature
solvent blend
film thickness
spray distance
flash time
air pressure
paint pressure
air velocity

In the original post, Jason indicated that the "fisheyes" did not appear immediately. This indicates that they are indeed not "fisheyes," but solvent pop. Fisheyes appear almost immediately or within a very few minutes as the finish does not cover the entire surface because of the contaminant. Solvent pop appears "later" after the finish has been sanded in most cases.
It just so happens that "fisheye eliminator" will not cure solvent pop.