Do BP head stamps change?

[Bogertophis]

This dropped the temperature in my enclosure from 86 to 81 degrees. I used a one quart plastic milk jug. Froze it overnight and put in in my enclosure in the morning. It kept the enclosure cool all day. My enclosure is 36 x 24 x 14.5 and it's made of plywood. I confess that I didn't wrap it. I was concerned that it would insulate it too much and thus keep it from cooling my enclosure. As far as I can tell, my snake stayed away from it.

I agree that snakes aren't likely to touch it anyway- once they get close, they'll back off, most likely in surprise. And the more insulated your enclosure is to start with (& yours is wood which retains temperatures very well) the longer the coolness will remain.