how hot is too hot when welding TPO roofing?

I've welded TPO at around 650°F too, but honestly, I've had days where even that felt borderline risky. I usually start lower - around 600°F - and slowly bump it up until the weld looks solid without getting shiny or brittle. It's surprising how much humidity and wind can throw things off... Have you noticed if certain membrane brands handle higher temps better than others? Seems like some are way more forgiving.

"It's surprising how much humidity and wind can throw things off..."

Couldn't agree more - weather conditions are often underestimated. I've noticed Carlisle membranes tend to handle higher temps slightly better than others like GAF. Still, starting lower and adjusting gradually is always the safest bet...

Interesting point about Carlisle membranes...haven't really noticed a huge difference myself, but maybe that's just me? I've always wondered if color plays into it too - like, does a darker TPO membrane heat up quicker and need less welding temp, or is that just overthinking things? Weather's definitely tricky though, had days where I thought I nailed the settings and still ended up redoing seams later...

I've wondered about the color thing myself - seems logical darker membranes might heat up quicker, but honestly, I've never noticed enough difference to adjust my welding temps. You're right though, weather's always the wildcard. Had days where everything seemed perfect, then a seam pops loose a week later. Just part of the game, I guess...

I've been wondering about that too - does ambient temp or direct sunlight make a bigger difference than membrane color? Sometimes it feels like I'm chasing my tail adjusting temps, and still get random seam issues. Maybe it's more technique than temperature...?