I'm no chemist, so I'm adding this just for any info it might offer. About a year ago, on a lark after reading some of Nagyvary's stuff, I took a cheap Strad copy, stripped the finish to bare wood, and removed the top. I made a saturated solution of borax by raising water to just under boiling and adding borax until no more would dissolve. I rubbed this hot into the wood on both sides (top, back, ribs) and waited for it to dry (which happened surprisingly fast with no warping of the wood. I bypassed any glue joints. I didn't expect any fantastic results, but only wanted to see if there were any detectable aural change in the overall tone of the instrument. Once dry, the surfaces were lightly coated with a white crust (probably oversaturation of the solution) which I removed with fine steel wool (was pretty hard to get off). I then reglued the top, and finished the instrument with my usual varnish schedual. I had no way to tell how deeply the solution had penatrated the wood (although after drying, the wood seemed slightly darker).
Of course, this was a very loose and ragged test with a lot of holes in the method, and no indication of what might have happened if I had boiled better wood in such a solution before use. The resulting instrument had a dull timber then before, with what seemed like a lack of overtones. Any brilliance the fiddle might have had before was gone. Response also seemed slower. I don't know if this was the result of the borax, or perhaps just the refinishing, but I was unimpressed.
I read somewhere that borax forms tiny crystals in the wood that the woodworm cannot eat, so it dies or leaves the source. Borax also apparently creates long strands in the wood cells that strengthen and harden the wood, but don't quote me on this.