"Quick question though—when you're using hot air on TPO, how do you gauge when it's just right?"
It’s definitely a balance between temperature and feel. Generally speaking, you'll want your heat gun around 950°F to 1050°F (500°C to 565°C) for TPO welding. But honestly, ambient temperature, wind, and even brand of TPO can shift things slightly. I usually do a quick test weld on a scrap piece first—if the material glosses slightly without scorching and you get a clean weld after cooling, you're in the sweet spot. Takes practice, but you'll get the hang of it.
I recently helped my brother patch his TPO roof, and we definitely learned the hard way about overheating. Like you said,
you're good—wish I'd known that beforehand... would've saved us some melted spots!"if the material glosses slightly without scorching"
Yeah, that slight gloss stage is tricky to catch, especially if you're new to it. I've found ambient temperature and wind conditions can really impact how quickly TPO heats up. Did you notice if the weather made a difference when you were working on your brother's roof? I usually try to avoid welding on super sunny days because the material heats unevenly—makes it way harder to control. Curious if anyone else has tips for dealing with weather variations...
Yeah, sunny days can definitely turn TPO welding into an unwanted game of "hot potato"... I've found early mornings or cloudy days are your best friends. Also, a quick temp check every now and then saves a lot of headaches later on.
"I've found early mornings or cloudy days are your best friends."
Couldn't agree more. Last summer, I was welding TPO on my garage roof around noon, thinking I'd just power through it. Big mistake... the membrane got so soft it felt like welding chewing gum. Had to redo half the seams later because they cooled unevenly and didn't bond properly. Now I always aim for early morning sessions or wait for an overcast day—saves a ton of frustration and rework down the line.
