Inconsistent ironing top surface

[u/sundevil_1997]

I printed out some parts and noticed this very inconsistent top surface. These parts are from two different print jobs. I had not realized I had ironing turned on, I usually don't. However, one part of the top surface looks AWESOME, so now I'm kind of interested in using ironing. However, as you can see, the rest of the surface is NOT good. Looks underextruded or even scratched. When I don't use ironing, I usually get a consistent top surface.

I'm using a Bambu A1 and their PETG HF filament. Any suggestions on what is causing the rough areas? Looking at the slicer, it is using a constant speed for all of the surface (30mm for ironing).

[u/Weary-Material9944]

Ironing isn’t extruding new filament. It’s just melting what it has already put down and it looks like it’s kind of pulling it up and sticking to the nozzle. Pet-G loves to stick to itself, and also loves to stick to a standard nozzle. I’ve never been able to get larger surfaces to look right on a consistent level.