Yeah, I've noticed the same thing. Midday sun can really mess with your welds, especially on lighter-colored membranes. I usually dial back the heat gun a notch or two if I'm stuck working in hotter temps, but honestly, early mornings are just easier all around. Curious though, has anyone tried using shade tarps or something similar to keep the membrane cooler during welding? Wondering if that's worth the hassle...
I've actually tried shade tarps a couple times, and honestly, they're more hassle than they're worth. They do keep the membrane cooler, sure, but dealing with setup, wind catching them, and constantly repositioning... just slows things down. Usually, I just dial back my heat gun and work smaller sections at a time. Early mornings or cloudy days are still your best friend when welding TPO. Ever noticed how much easier the seams weld on a cloudy day compared to full sun?
"Usually, I just dial back my heat gun and work smaller sections at a time."
I get what you're saying about the tarps—wind can really make them a pain—but dialing back the heat gun too much can sometimes compromise weld quality, especially if you're rushing to beat the heat. Personally, I've found that using a portable pop-up canopy (weighted down, obviously) can be a decent middle-ground. Quick setup, less hassle with repositioning, and keeps things manageable even on scorching days. Might be worth giving it a shot sometime...
I've tried the canopy thing before, and it definitely helps if you're stuck out there all day. But honestly, I think the real trick is just finding that sweet spot on your heat gun. Too cool and you're right—your welds won't hold up. Too hot and you risk scorching the membrane or weakening it. I usually test mine on a scrap piece first to dial it in...saves me from guessing later when I'm sweating buckets and just wanna get done already.
You're spot on about testing on scrap first—it's a lifesaver. But honestly, I'd say the sweet spot for TPO welding usually lands somewhere between 900°F and 1000°F, depending on your gun and the membrane thickness. I've seen guys crank it way past 1100°F thinking it'll speed things up, but all they end up with is brittle seams that fail inspection down the road. On the flip side, too low and you're just wasting time reheating and reworking seams that won't bond properly.
One thing I've noticed during inspections is that ambient temperature and wind conditions can really mess with your settings. Even if you dialed it in perfectly yesterday, today's weather might mean tweaking it again. So yeah, always test first—but also keep an eye on how your weld bead looks as you go. If it's shiny and smooth without discoloration or bubbling, you're probably good. If it starts looking dull or scorched...time to back off a bit.
