Foam plug in mash tun

Hi all....I have read that some people use stiff foam cut to fit in their cooler mash-tun. What kind of foam would I use...pink/blue board? And do I need to wrap it in something like plastic or is there no problem if it should come into contact with the wort/mash? Thanks

Yeah I do that. You can get different thickness from Home Depot. I use the white stuff located in the lumber dept. It came with a thin layer of plastic attached to it that said mold resistant or something similar. Can't quite remember. Mine doesn't come in contact with the mash although the corner hits occasionally when I am putting it in or out. I think most coolers taper a bit or have a lip just inside the top that it can rest on. The real handy deal is you can poke the thermometer right through it and it will hold it in place. Really holds in the heat.