
I have both a cool mat and a cool coat, but I wonder if they are different to yours.
The cool mat is a bright blue plasticy rubbery sort of material which has a gel inside that when compressed, like when a dog is lying on it, becomes cooler. I have a lovely picture taken yesterday of my GR lying on her back on the mat in order to have a cooler tummy as well as her back.
The cool coat which I used on my previous dog when she was older and had a heart problem, is made of a material not dissimilar in feel to chamois leather which I soak in water, wring out so that it doesn't drip, then put on the dog which kept her cool for three hours roughly, but of course, it could easily be re wetted. After use I would leave it out to dry thoroughly before storage. It will then go quite stiff feeling, but went back to being supple once immersed again in water. I never left it stored damp.