Fish Eyes

[Mr Eddie]

I retired at the end of last year so I'm finally getting some real shop time. My first project has been a work table for one of the little guys that comes to my shop. He just turned 6! The table top is 2' x 3' and I used GF Oil and Urethane top coat. First coat went on fine and I sanded with 400 grit before applying the second coat. Everything looked good. I decided to use 600 grit after the second coat thinking it might help the final coat. The third coat looked good when I applied it but as it dried the dreaded 'fish eyes' starting appearing.

I know silicone and other contaminants can be the cause but I wonder if something I did contributed to it. I wiped the top, legs, and aprons down with a tack cloth before applying each coat of finish. The tack cloth I used felt waxy to me. Are there different types of tack cloth available? I also applied a heavier coat of finish to the top on the last coat - legs and aprons I did as I had the previous coats. The heavier coat of finish on the top is the only thing I did differently than the rest of the table (legs and aprons).

I now know that applying a coat of shellac can be helpful in preventing this type of problem. Any suggestions would be appreciated.

Lonnie

[cputnam]

Some sandpapers have silicone in them - could have been the source.

[JR1]

Never ever use tack cloths. They don't do the job and leave threads and contaminants behind. Vacuum, blow off with compressed air (make sure that there is a water/oil trap on the line or wipe with a rag or paper towel moistened with MS or DNA (no DNA on shellac).

[Restorer]

never ever use a tack cloth. wipe dust off with a rag dampened with mineral spirits and let it go at that. tack cloths are a waste of money and as you see will now cause you to most likely have to strip the finish completely off before you can apply your finish. trying to sand it a little never seems to work at least for me. Now half a dozen folks will be along to say how tack cloths are great but you used the wrong brand. imo tack cloths are best left in the store along with general finishes but that is another debate. In your case I would bet, and I have been there done that in yrs past, the tack cloth is the problem. toss them out do not use them. Also I never handle a piece I have started the finish process on with bare hands, even while sanding between coats, I always wear nitrile or some type gloves once I start the finish process. Natural oil on your skin or that hand lotion for dry skin gives you nice looking fish eyes also and the quick wipe down sometimes will not get it off. gloves are cheap insurance to protect the process and a lot less troublesome then having to strip a piece with fish eyes.

[Mr Eddie]

Thanks for the replies. Regarding the tack cloth - I wondered how something that felt so waxy could clean the surface without leaving some type of residue. Fortunately, my 6 six year old client won't ever notice the fish eyes so I'm at least saved the effort of sanding and starting over. I've learned a lot from building this little table.

Lonnie

[Howard Acheson]

Many store bought tack cloths contain contaminants that can be transfered to the wiped surface. In addition, tack cloths can transfer contaminates that they pick up from a wiped surface.

It's never a good idea to use a tack cloth.

[jteneyck]

cputnam said:

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Some sandpapers have silicone in them - could have been the source.

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Are you sure you don't mean zinc stearate? Never heard of silicone being used on sandpaper.

John

[cputnam]

John,

Might could be. At this point I don't even remember what stearates are supposed to do for/to sandpaper/

[jteneyck]

Here's some info. of why zinc stearate is used on sandpaper.

John

[Sawdustd]

In the future, use a micro-fiber cloth. They pick up dust like a magnet.