Heat resistant tape is needed to attach the transfer to the mug. It’s also a good idea to place another piece of plain copy paper around the mug to prevent ink from getting on the press or mug wrap.
If you are sublimating mugs in a convection oven, then you need mug wraps that fit the mug size you will work with. You should also use an analog temperature gauge that you can place inside the oven to make sure the oven temperature is set correctly. Keep a bucket of warm water handy to place a ceramic mug in after it is removed from the oven or press. This will cool it down quickly to prevent the ink from degassing.
