In a house full of smokers the sealant or adhesive used around the frames has yellowed over time. I could redo it, but the installer was a bit (a lot) untidy with the stuff and I need to remove the excess before starting work. Is there a solvent that will do this? It doesn't appear to be silicon since it's dried hard. Any ideas on the type of sealant/adhesive used? Failing that, is it practical to buy some quarter-round upvc strip to cover the old stuff up completely? And if so where could I source this?