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Adding thickner to epoxy for pore filling http://luthiersforum.com/forum/viewtopic.php?f=10101&t=28026	Page 1 of 1

Author:	Philip Perdue [ Wed Jun 30, 2010 8:24 pm ]
Post subject:	Adding thickner to epoxy for pore filling
I attended a presentation on finishing last night with the Stringed Instrument Makers of Southern California. One of the demonstrations was using epoxy as pore filler. The presenter used Silica to thicken the Z-poxy. The reason for the silica is to thicken the mixture. They also thought it helped the epoxy mix stay in the pores better. I have never used a product like the silica. When the silica is in the mix is it invisible? The only thing I can think of SAND and it can be seen and would be cutting the wood. Any thoughts? Philip

Author:	JohnAbercrombie [ Wed Jun 30, 2010 11:36 pm ]
Post subject:	Re: Adding thickner to epoxy for pore filling
A few thoughts- (I've used quite a bit of silica in WEST epoxy, but not on guitars.) 1- Not all 'fumed silica' is created equal- the 'original' was Cabosil which I found mixed into a transparent 'grease-like' thickened epoxy mix. Other no-name silica additives, which I seem to get these days, mix up white and are white when the epoxy cures. 2-You don't want to have to sand this stuff- it is hard. 3- Wear good dust protection (mask) when you open the silica - it is extremely easy to get airborne and is not at all good for your lungs. Avoid air currents. Like Todd, I find that the consistency of the epoxy is about right without filler. I'm still looking for the 'perfect pore filler', though. I'm getting quite a collection here! There's nothing like a few Wenge orphan sides/backs for test panels to really check out your pore filling technique! Cheers John

Author:	Stuart Gort [ Wed Jun 30, 2010 11:37 pm ]
Post subject:	Re: Adding thickner to epoxy for pore filling
"Fumed silica" (Cabosil - Aerosil) mixed into epoxy will result in a thickening and whitening of the mixture. Both effects will be more intense as you add more fumed silica. The idea behind adding fume silica to epoxy in a pore filling application to provide a non-sag property to the epoxy mixture is sound. It can keep epoxy from running out of a pore......assuming it gets into the pore. There's the rub. The less liquid you make the epoxy, the harder it will be to get it down into the pore. The trick to using it will be to not add so much that it turns white and not add so little that it runs out of the pores too easily. At the viscosity of toothpaste, it's going to be fairly white and I doubt you'll want to use it without adding a dye.

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