I replied to Peter on this, but thought I'd chime in here as well.
I have done a few instruments with the egg white / sanding dust slurry method and it does work a treat. Depending on the size of the pores needing filling, it will take from one to several applications, but it does go quite fast, especially if you get the hair drier out to help speed things up a bit. Though I think you are best to give each application some time to dry on its own.
It's about as non toxic as your are likely to find for a pore filler, and pretty darn cheap to do as well. What it doesn't do though is to make the grain / figure in some woods really "Pop" like epoxy will do. For instance, on Australian Blackwood (cousin to Koa) it leaves the wood looking smooth, but a bit lifeless, whereas with the epoxy (I use WEST Systems) it gives the wood a depth and vibrancy that I'm looking for.
On Indian Rosewood and mahogany I couldn't see any difference between the egg whites and epoxy, so depending on what you are wanting to do this might just be what you are looking for.