You will get many opinions on this. I use parchment paper. I also have the teflon sheets and butcher/kraft paper. I prefer the parchment paper. Sometimes teflon will give the transfer a shiny look or sometimes the texture will be able to be seen.
What size and brand is your heat press??@C - thanks for that, what site do you recommend for these teflon covers?
Heat Press Nation - Digital Heat Press Transfer Machines, Heat Transfer Paper, Protective Base Covers@C - 15x15 vesta heat press