When I used to smoke, I smoked handrolled fairly often (but not exclusively, since it's a pain sometimes, especially when driving or anything else that requires your hands). When I first started smoking them, I didn't use filters, but, after I started coughing up nasty shit in the mornings (mine was red and brown, though, not green), I went out and bought a bag of cotton filters.

The filters are pretty cheap, especially when you consider that you're wasting less tobacco (since you're not throwing a butt full of it into the ashtray). I never tried boiling them, but I suspect this would not work, at least with the ones I had, as they were kept together with a thin paper wrapping.

The only disadvantage of the filters is that you can end up wasting a lot of tobacco if you usually roll thin cigarettes (since you have to roll it the same width as the filter), and it can be a bitch to roll them until you get used to it.

As an interesting bit of trivia, I first learned about these filters from a junky friend of mine, who used them in place of a cotton ball when he shot up. He said they're more efficient at sucking up the precious h in the spoon, since they're much tighter.