Today, after cutting out a couple of Little Big Men Studios shield transfers, I could not get the protective clear film off the sticky side.
I had pondered about this problem in advance, as I have heard that it sometimes happens over time, and I have previously had a couple of transfers ruined.
I have often experienced that temperature can heavily impact the stickiness of adhesives, and I decided to try out heat to soften the 'glue' on the transfers.
Holding the transfer with a pair of tweezers, I used a hair-dryer to heat it up (for about ½-1 minute), and then it was possible to remove the film and attach the transfer to the shield, as normal!
I successfully applied this method to both the transfers, but I think that it has to be repeated several times to prove effective (I may have been lucky).