Q: I am building my 10th guitar and am using epoxy over bare Indian rosewood to fill the pores, with great success. Can I also apply epoxy to the soundboard to eliminate “spruce ripples” and also fill voids in the rosette?
A: You can, but I would not advise it, though it might make an interesting experiment for a few guitars. The problem is that softwoods, like the spruce used on guitar tops, tend to absorb a good bit of impregnating coatings such as epoxy.
The beauty of spruce is that it has a high stiffness to mass ratio. In other words, it produces good tone because it is light, but stiff. Adding epoxy to the wood will increase its mass, and is not likely to add to its stiffness. Thus, it is likely to result in a slightly duller sounding top.
That said, I do know of a number of people who use polyester as a curing filler, even on spruce. It is admittedly much more brittle than most epoxies, and therefore likely to be a bit less problematic, but I’d want to hear a dozen identical test guitars, half with and half without curing filler on the tops, before I’d be convinced there was not some loss of tone in the process.
Michael Dresdner
straight talk about wood finishing
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