Danger to underlayment using light torch on flashing?
This is a So-Fla HVHZ concrete tile roof, but I'm sure the principles apply elsewhere. The galvanized edge flashing was too new, and not properly etched, before an expensive primer (designed/labeled for just this application) was applied.
All LOOKED well for 21 mos. until Hurricane Wilma came through, and gave it a good sandblasting. It's looked very "poxy" ever since. FINALLY getting around to addressing this... (hey, gimme a break, it's cosmetic, and it's not visible from the street. ;')
I supervised this roofing job back in 2003, so the details have faded a bit. IIRC, the L-section flashing was nailed down after the felt, but before the hot-mop asphalt layer. Per newer codes, there's a 1x2 strip that spaces it out from the rafter ends/sheathing edge.
Anyway, I want to strip the old primer, rub the bare flashing with white vinegar to micro-etch the surface, and have another go at the primer... maybe even follow up with paint this time, LOL.
Was contemplating messy chemical stripper, when someone suggested ye olde propane torch. Sure enough, a few seconds of even the cooler tip of the flame, and the primer scraps off "like buttah". Did a tiny test section, didn't smell anything like burning tar... so, is it a roof-safe method?
Also, I remember that roofers use propane to melt the hot-mop tar (570degF, IIRC); add to that the not-great heat transfer of thin sheet metal, and the dissipation offered by the adjacent cool sections, and I think I've got "margin" to play with.
BUT... wanted to bounce it off the RKIs/experienced DIYers here to see if any yellow/red flags went up!
Thanks in advance.