Coasters turning brown in press

[AJG]

Going slightly bonkers trying to figure out why my uni sub coasters (cork backed) are turning brown

i have a UkPress 38x38 Pressing for 60 secs at 180c
I use Teflon sheet over the top of coaster.
ive tried varying temp and pressure to no avail (also removing Teflon)
ive tried with sub paper and without to which I get sane brown result.
The photo attached is far left original white coaster far right being pressed.
if I press cooler or less pressure the image fades.

Any ideas?



Thanks!

[AJG]

[ATTACH=CONFIG]5985[/ATTACH]Here are the beauties. Left is without press . Right and bottom are the result of pressing. This is without sublimation paper. If I reduce the heat the transfer doesn’t take.

[Justin]

How does the actual printed image look?

[AJG]

Great, really sharp.Not burnt, no blacks/brown to indicate heat issue. I’ve gone through an entire pack of coasters trying to figure it out. I haven’t a heat gun but wondering if temp on press is reading lower than it actually is .... hmmmm

[Justin]

To be honest from your photo's I can't really see any major issue? There is obviously a slight colour change in the surface of your coasters but if they're printing perfectly is this an issue?

[AJG]

The image is in the middle of coaster, I'm leaving the area around it white (Or transparent to show the white of the coaster).
I use to outsource the design and they manage to get the coaster white with the image in the middle. I know it doesn't look a huge difference in colou but when you put a white mug on it they look really yellowed.

Do you use parchment paper? I'm using Teflon and tried doubling up but still to no avail.

Thanks for getting back to me!

[Justin]

Appreciate what you're saying when the mug is placed on. I've never seen this with Unisub coasters. If I do coasters I don't tend to put anything on top. Is it a new piece of paper? The paper I use does brown after a few uses which may not help.

[DouglasCas]

Appreciate what you're saying when the mug is placed on. I've checked out standing desk chairs here and never seen this with Unisub coasters. If I do coasters I don't tend to put anything on top. Is it a new piece of paper? The paper I use does brown after a few uses which may not help.

What could be causing the paper to go brown so quickly?