It looks to me like stabilizer..a wash -away type. In fact I have a brand (old) in my stash called 'Stitch n Spray' that must be kept in a sealed plastic bag or it dries out & is ''crinkly'' as you described. I would suggest you soak one in water & see what the result is. In fact, I quote from my pkg...."Occassionally when a sprayed item dries, the area where the Stitch n Spray had been, may feel a bit crisp. This is due to remaining residue which will wash away during laundering". As a rule it can be sprayed w/water after embroidery, or wiped w/a wet cloth to remove all remainder. You can tear away as much as is possible. I used it frequently for topping a napped project. Now there are other brands to choose. The donor probably tho't it should remain on the blocks until your project was completely finished & then laundered.