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| Behlen's Varnish Issue http://luthiersforum.com/forum/viewtopic.php?f=10101&t=22730 |
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| Author: | dmills [ Sun Jun 14, 2009 11:21 am ] |
| Post subject: | Behlen's Varnish Issue |
I just completed a guitar (posted some pics yesterday) that I finished with Behlen’s varnish. This is the second guitar I have finished with Behlen’s and I am happy with the results overall. However on this current guitar I experienced a strange issue. I was using the thinning mix recommended by Alan Carruth in previous posts and topped off the storage jar with Bloxygen after each coat. However, after just a couple of days the mixture started to thicken rapidly to the point where the new coats would not self level. I had to resort to mixing a new batch every 3 or 4 days and increase the amount of thinner to about 30 to 40 percent. No problems with the drying time however once the new coats were applied and the final result buffed out nicely. I think I've read a few references over the last year or so to varnish users switching away from using Behlen’s due to a formula change that altered their results in a negative way. Does anyone know when this change occurred and what the results were compared to the original formula? Don’t know if this was the source of my problem or if I just was unlucky and happened to purchase a can that that was at the end of it’s shelf life. Has anyone used the Pratt & Lambert #38 clear alkyd gloss varnish with good results as an alternative to Behlen’s? |
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| Author: | truckjohn [ Sun Jun 14, 2009 12:22 pm ] |
| Post subject: | Re: Behlen's Varnish Issue |
Sounds like it is evaporating solvent very quickly. How hot is it where you are at? Are you storing it in a cool place? 30-40% reducer in the mix would make my varnish watery thin.... and drying already takes me 1+ hour to not be tacky... This is indoors, so ~78F and whatever humidity is in a damp bathroom. I haven't used Bloxygen, but add marbles or glass chips to fill up the can to the lip.. So far, it works very well without any trouble of polymerizing in the can. I try to minimize can open time as much as I can.... so I brush 1 coat, add more marbles, then hammer the lid back on the can.... then go clean brushes and do other tasks. I use the Al Carruth Behlens Rockhard Recipe with cans bought ~1 month ago. I did find that after a couple coats, it needed another splash of reducer/thinner to loosen it up a little. It didn't take much, though. Maybe a tablespoon or so in a quart can. I haven't had any trouble with varnish polymerizing in the can except for a stalactite or two on the lid. Good luck John |
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| Author: | dmills [ Sun Jun 14, 2009 1:06 pm ] |
| Post subject: | Re: Behlen's Varnish Issue |
Hey John, Thanks for the input. Don't think evaporation was the issue though. I would typically pour 4 ounces of varnish into a small mason jar and add thinner, etc. for the finish mix. The mason jar was sealed quickly after applying a coat and the Behlen's can was sealed immediately after adding a big squirt of Bloxy. And I was applying the finish in my basement workshop in the middle of a Chicago winter so my ambient temp was probably around 68 degrees and the humidity was probably low 40's. Both the can and the mason jar mix thickened fairly quickly. The odd thing is, this didn't happen with a guitar I finished with Behlen's about a year and a half ago and with that round, I wasn't using anything to ratard the polymerzation, just sealing the can/jar quickly after each use. |
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| Author: | Alan Carruth [ Sun Jun 14, 2009 1:55 pm ] |
| Post subject: | Re: Behlen's Varnish Issue |
It sounds to me as though the Bloxygen isn't working, or maybe you aren't closing the can as tightly as you should. I use the 'marinated marble' trick myself, leave only about 1/8" of air at the top, and clean the rim of the can and the top pretty frequently to keep things tight. Even so, I had a can skin over a little recently: must have left some hardened finish on the rim. It's probably best to just throw out any varnish that has skinned over or thickened up. If you're desperate you can filter out the gelled stuff with a piece of window screen. DON'T try to mix the gelled varnish in: you'll just end up with lumps of gel in the coat that will have to be sanded out. |
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| Author: | guitarjtb [ Sun Jun 14, 2009 4:00 pm ] |
| Post subject: | Re: Behlen's Varnish Issue |
Use the marble trick, seal the can, turn it upside down and slightly tilted. Tilting helps keep stalactites from forming. James |
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| Author: | douglas ingram [ Sun Jun 14, 2009 9:09 pm ] |
| Post subject: | Re: Behlen's Varnish Issue |
Only thin as much varnish as you are going to use that day, or the next. Simply adding thinner and mixing it in will add oxygen into the varnish, no matter how little air is in the can. If thinned varnish is too thick to use without thinning further, its too far gone to use at all. Buy cans as small as you need, buy two or three if you need to. Unopened cans store best. Good luck. |
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