I bought two 25m rolls a couple of years ago. One has brandname (Vlieseline), 12 sec **(medium heat) no steam stamped in the selvedge, the other is for stretch fabrics, that has Vlieseline 8 sec ** no steam stamped along the edge. I keep them in plastic sleeves and both work well.
I keep mine sealed in a plastic bag as was suggested in the instructions. (same product but another brand beside Vilene)
Good Luck with this one. I have a large amount of the iron on fine stuff that doesn't iron on for very long... them carefully falls off... I do usually use a pressing cloth though.
As far as I recall - DRY IRON.
I use a Teflon sheet or a piece of old cotton between the Vilene and the iron to prevent sticky accidents. And sometimes some old sheeting on the ironing board to protect it too.
Look for the dots on the Vilene, that is the glue and that goes against whatever you are ironing it to.
Humidity can affect the results.
Good Luck.