I was thinking of applying Hammerite underbody seal with waxoyl, however I've been re-felting my shed and find I have a good bit of Bostik felt adhesive left over. It's black and gloopy like treakle, and claims to remain flexible, moving with the felt as the temperature changes. So, I'm wondering would it make a decent underseal? Maybe it would pick up several hundredweight of road grit as i drove along? Any information, thoughts or musings? Ta.