If I finish anything… well, I usually use polyurethane (only partial by my ignorance). Lately, I have been using the MINWAX, Fast-Drying, Clear Gloss, Poly. I thin it about 25% with mineral spirits. Although I like the way it goes on and set up time, I think 3 coats is the prime number, no more, no less.
I did encounter one phenomena. After thinning, using for short periods a day, over a period of 4 or 5 days, I started noticing tiny granuals in the poly as it dried. I figured it was just from the mess in which I work in and was more careful not to raise dust and made sure the surface was totally clean and smooth. After a week, they were really bad. I couldn’t see anything in the can. So, I decided to strain it through a coffee filter in a paint filter. WHOLLA! CLEAR GRANUALS! 1/4 teaspoon full, anyway.
I am assuming the Fast-Dry in the poly causes something in the mix to crystalize. Any body ever experienced this?
I am ready and anxious to try laquer.
Replies
Your varnish in the can is starting to cure. Happens to oil varnish too. The faster curing, the worse the problem. You can use bloxygen or marbles in the can to minimize it, but as soon as you open the can the process starts. Some kinds just make a skin on top, but some start curing and form little grains. Unless I just opened a new can, I filter what I'm going to use.
Sounds like it was an old can that hadn't been closed tightly. Hopefully it wasn't water based poly since you mentioned thinning with mineral spirits.
I've never had that problem, but I'm a fanatic about cleaning the rim of the can and closing it tightly.
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Yep! I'm with Bob, I strain it through a tea-strainer.
Regards...
sarge..jt
Proud member of the : "I Rocked With ToolDoc Club" .... :>)
I usually perforate the rim of the can with a nail,all around the perimeter, to provide a good seal when closing the can.This should help.
Or, even better, use a small, unwaxed paper cup to dip the varnish out of the mother can. And of course, don't return the unused portion back to "Mom". If you have ready access, nylons/pantyhose make a good strainer.
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