thanks for all of the replies
I dont have access to a heat gun unfortunately. how much are they, and are they hard to find?
I have been cutting everything in the same direction on the paper (I imagine that the grain all goes one way on each sheet?) which is why I was really baffled
I may be posting in a wrong place, so please excuse, as I could not find where to reply, but did want to try and help you with the curling. Someone told me to place a piece of parchment paper over your pieces and it will keep pieces from curling. As I do my pieces in my oven, I still keep a watch on the pieces, as you can see the pieces move, as the paper will rise up, so you can see and 99% of the time, no curling. Hope this helps, give it a try.
Im not having a problem with getting them flat, its just the left-over burn mark from the curling. I will try the cornstarch method, though I must confess to being a bit nervous over putting cardboard in the oven!
maybe it is the quality of my plastic - I dont have name brand shrinky dinks, it is a different company. but it wasnt cheap and although i forget the name right now, it was made by a company that does tons of scrapbooking stuff.. who knows.
thanks for the help guys,