Waist trainer and thermogenic gels

My bf bought me a waist trainer (because I’m always complaining about my stomach and how I was going to buy one anyway, not because he thinks I’m chunk). The directions to wash it say that I knew to hand wash it with a cloth and mild soap. I want to also use a thermogenic gel, so I will sweat more. Is the process of washing it going to be the same since now there’s going to be gel involved ? Also which gels do y’all use?