how hot is too hot when welding TPO roofing?

Interesting point about the canopy, though I'm not entirely convinced it's practical for every situation. I've found that even with shade, humidity can still wreak havoc on weld consistency. Have you considered adjusting the welding speed or temperature settings slightly during peak heat? I've experimented a bit and noticed minor tweaks sometimes offset the gummy texture issue - though admittedly, results can vary quite a bit depending on the specific TPO brand and thickness...

Good call on adjusting the welding speed and temp. I've noticed the same thing - sometimes just dropping the temp 10-15 degrees or speeding up a touch helps keep things from getting gummy when it's blazing out. Another trick that's worked for me is welding earlier in the morning whenever possible, before the humidity really kicks in. It's not always doable, but it can save a lot of headaches on tricky TPO brands. Also, cleaning the nozzle tip more frequently seems to help too...keeps the airflow consistent.

I've been messing around with my own TPO roof lately, and honestly, I'm still getting the hang of dialing in the temp. Dropping it by 10-15 degrees sounds reasonable, but how do you guys actually tell when it's just right? I've tried the morning welding trick too, but sometimes even then it feels like I'm guessing. Maybe I'm overthinking it, but is there a specific sign or feel you're looking for to know you're in the sweet spot?

Honestly, I think focusing too much on temps might be throwing you off a bit. When I first started, I was glued to that dial, but eventually realized the trick is more about watching the seam reaction. If you see the membrane edges getting shiny and slightly tacky (but not melting into goo), you're in good shape. Took me a few years and some messed-up seams to trust my eyes over the thermometer...but now it's second nature.

That's a good way to put it...but have you noticed if weather conditions or humidity levels affect how the seam looks or reacts? I've had days where everything felt dialed in, but seams just weren't cooperating - wondering if it's just me.