The original solvent or carrier is water for the PDMS and therefore the rain desolved the dressing that was attached to the vinyl.
Here is a little trick to reduce that , keeping in mind that all dressings are just that, a dress you put on a material to make it look a little better for a short time.
Put on a light coat, let it almost dry and then buff it dry with a towel. This "sets" the resin, don't care what name is on the bottle, all the PDMS dressings are basic, just different resin content.
