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| caution: varnish question http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=9981 |
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| Author: | gburghardt [ Sat Dec 23, 2006 5:34 pm ] |
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I know that less folks use varnish as some other available materials, but i must ask anyway. Does varnish have a shelf life? I know shellac is around 6 months, but I'm not sure about varnish or anything else. In case it matters, I have some tung oil varnish that I purchased around 1 year ago and just let it cure for 3 weeks after finishing a mandolin with it and the finish started peeling after I began wet sanding. I think one or more of several things could have happened: 1) The varnish did not properly adhere to the shellac sealer coats. (definitely happened) 2) The wet sanding paper had something in/on it which dug into the finish and pulled a bit of it off. 3) any other issue I can't think of right now. So, since the finish is ruined I decided to see how tough this varnish is and man, it took some effort to get my fingernail to scratch it! Has this happened to anyone else? How can i make sure it doesn't happene again? By the way, Merry Christmas everyone! (well, christmas eve) |
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| Author: | TRein [ Sun Dec 24, 2006 2:17 am ] |
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Geoff, What was the brand and name of the varnish you had the problem with? We need to start there to figure out what went wrong. As for shelf life: it varies on the varnish. Most oil varnishes will skim over in a partially filled can unless you use Bloxygen or something similar. If the varnish skims over, you are pretty much out of luck unless you strain the remaining varnish through a very fine mesh filter. Even then, you are spreading partially polymerized varnish and it may not flow out very well or dry completely even. As an aside, I was speaking with Paul Fischer last fall about the varnish he uses. He managed to lay in a stock of Behlen's 4 Hour varnish before it was discontinued. He says it improves with age and will not hesitate to use 4 Hour varnish that is decades old. Interestingly, he said it does not skim over in a partially filled can. That leads me to believe that there was some sort of spirit varnish component to the 4 Hour in addition to a polymerizing oil varnish. Odd that Behlen ceased production as it was a favorite of many. |
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