Are both sides of pot holder heat resistant (can be touched by hot pot)?
It’s personal preference what you want to use. Acrylic is good if you want to just quickly take a hot pot off the stove. However, you can’t use it as a trivet. The yarn will melt and get black and hard. Acrylic is plastic. I have had some catch on fire so you need to be careful not to get too close to heating element or burner. I would recommend cotton yarn. If it does catch on fire, it scorches but puts itself out. The same with wool. You will need two sides and sew them together to make really thick ones. I held two strands of worsted weight together, made two squares and sewed them together. They work great. Mine are acrylic and as you can see, are well loved. You can get a silver quilted heat resistant fabric from fabric store to put in one side. But they will burn your hand if you do all knit in a single layer. They must be doubled.