[rwilsontx]

I'm forming some 0.020" PETG material. I found a supplier online and have been using their material for some time and it works great. Recently they had supply chain issues (I know you're shocked) so I ordered some from a different supplier of the same spec and about the same price.
However, the new material forms completely different so I'm trying to see what the difference is. I called both suppliers and they both just say it's PETG, 0.020" thick (which I've confirmed they are the same).
The original material had a blue coating on it which was removed before putting in the holder of the vacuum former.
The material was loaded in and it would get very wavy and then pull tight and completely flat and then start to droop which is when I would form the parts, perfect, beautiful and consistent.
The new material has a clear film that gets removed. When put in the vacuum former to heat, it gets wavy and sags, never pulls tight/flat. To get soft enough to form, I have to let it sag more than is convenient for the mold, so it almost always wrinkles.
I'm trying to figure out what's different between the two so I know what to order. Is one virgin material vs. recycled? Is one cast vs rolled?
I'm truly curious since at a high level they're supposed to be the same.
Thank you,
Bob

[RCaffin]

Opinion only, based on vacuum-forming work done for me decades ago:
(Dear me - that long ago?)
If the first material vacuum-forms very well, I have some doubts whether it is standard PETG. Of course, I might be wrong - very easy.
Then again, given your description of how the second material behaves, I have doubts about it as well!

What is the vacuum-forming tool made of? How are you heating the material?

Cheers
Roger

[peteeng]

Hi Bob - When plastics are made they are stretched. Some quite a bit which sounds like the first lot. The material is softening then shrinks to its original size then you stretch it again over the form. The second lot is softening but not shrinking to tighten, so you will have to find the original stuff. One thing to try is drying the material. The water content can have an effect on its performance. Do you dry the sheets before you form? They will be both PETG but the first one is "oriented" vs the second is not oriented or stretched to thickness. Peter