When mummifying with pallet wrap (or any non-breathing wrap) it's best to poke holes in areas on the bound person. It allows a little bit of air to get in to cool and a little bit of heat to escape. In one session with my former Mistress, I was mummified for 2 hours before a cramp started bad, the heat and breathing were not the issue for me.
Another tip - if the head is encased, of course we leave area to breathe through, but leave a decent sized area on top for the head to release heat. Our bodies release a lot of heat through the head and we would not want our brains to boil....
Another tip - if the head is encased, of course we leave area to breathe through, but leave a decent sized area on top for the head to release heat. Our bodies release a lot of heat through the head and we would not want our brains to boil....