Coasters - inconsistent colour

[Matt_VII]

Hi guys, wondering if you can shed any light on this.
I made a large order using the Xpres hardboard coasters. The prints were all fine (clean heads, same paper etc) press time/temp/pressure the same, but got a different result on some coasters. As you can see in the pic, the right coaster is correct and the left one looks much more desaturated in the browns.
I use an Epson L805 with Ink Experts inks and paper.

Is this possibly due to the coaster stock? It's the only thing i can think that's different.

Any help would be much appreciated

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[Justin]

What heat press are you using? Just wondering if there may be temp issues.

[Matt_VII]

I'm using the Adkins Magic Touch swing press.
I press 6 coasters at a time and can get 6 perfect ones and then all 6 will be the desaturated brown on the next batch.