Slick 60's

The PO of my truck drilled several 3/4" holes in the floorpan for some bucket seats he pit in. I was just going to use some fiberglass mat to fix them, but there is also some rust bubbles starting to form. These are only on the topside, not underneath. Has anyone used the POR15 kit for floorpans?

I have used POR 15 before. I've never used the patching compound for anything larger than pin holes. I know they make a mat that is supposed to get as hard as a rock. If it we're me I would weld in new metal. However, if you don't have access to a welder that would be easier said than done.

cut out any sign of rust at all, then weld patch panels in. If you cant weld in patch panels (dont have access as fishtank said) then fiberglas it.

get a piece of cardboard or somesuch, ducktape it up from underneath (if youre working from the top) then glass the mat in over it to fill the hole making sure to overlap onto the steel a good bit. Then just remove the cardboard when its hard and youre done.

POR 15 and fiberglass mat work very good if you dont have a welder.
i have done both and seems they are equally strong.i had a friend who did his mustangs entire floor with POR 15, then when it hardened tried to bust a hole thru with a hammer and did not succeed.not sure how hard he hit it but he was very happy it did not break.

I should explain my reply though...

no matter what you do, fiberglas or welding, make sure you cute out all signs of rust.

if you dont it will come back and haunt you in some way shape or form. At the very least if you can't cut it out, sandblast it right before you glass over it.

Thanks for the replies everyone. I have used fiberglass on other things, and it lasted. In the late 60's I worked for a company making fiberglass funnycar bodies. I was thinking the POR 15 kit might work even better. I don't have any rust through on the pan, but there is some bubbling in the paint on the floor. I really should get a welder and learn how to use it.