Well our big pneumatic press is fantastic but come across one substrate proving to be a little difficult to get a consistent and even heat and that is pre-hemmed tea towels. See photo:
tea towel.jpg
Basically I guess there is not enough pressure or due to the thick foam pad under the substrate then the raised hemmed sections are being pushed down into the foam resulting in the non-sublimated areas next to them.
I think I might head to B&Q to get a sheet of MDF to place under to see if that helps flatten the tea towel under pressure but anyone else have other ideas please?