Fiberglass canoe restoration. The interior was bare fiberglass, probably with polyester resin, with previous house paint stripped off. The FSP was used just before automotive urethane. Toxicity was low, akin to TCP. It appears to have pumice in it and a mild sudsing action. I used the red Scotch-brite but didn't have to rub very hard. After rinsing there were no bead areas so it appeared to work. Also, the urethane appears to have adhered well.

Not what I expected. Messy and thick, like brown soft scrub

YMA601 is the best product I have found for removing mold wax from gelcoat before applying bottom paint. On a new boat the wax is there even if you can't see it. Fiberglass Surface Prep when scrubbed with a scotchbrite pad skuffs up the gelcoat a little helping the paint to stick better.