Re: Cleaning dirty records
Yes, that works. There's also the stuff that's used when making a person's face cast (which I can't recall the name of), but glue is likely to be cheaper.
PSA: NOT plaster-of-paris, unless you want the person whose face you're casting to end up looking like a cross between Two-Face and the Phantom of the Opera. PoP generates lots of heat as it sets, and there've been many cases of people foolishly using it to take casts of their hands or other extremities, and suffering amputations as a result.