David Weaver
just giving a brief look around, I see whitening toothpastes often have that in them. I figure that if I use whitening toothpastes, I'll just make little grooves for all of the coffee that I drink to stain, so ...

...well, I've got some old tubes of whitening toothpaste. we'll see what they do. If they work on softwood, then you know they're golden.

Seems a bit harsh for teeth, but maybe it's broken down quickly in the presence of water.