Possible mash tun?

[DaddyLouLou]

Has anyone tried to make a mash tun from a polystyrene "fish box", like this http://www.ebay.co.uk/itm/54-LTR-POLYST ... 419cf31dd8

It's a lot cheaper than a cool box, and I believe they're 1" of polystyrene, so it should hold temperature OK. Also, it should be easy to cut a hole for the plumbing, but:
Is it food safe (I guess so, as it can be used to transport fish)?
Can it handle temperatures as high as ~80°C?
Will I be able to get a good seal around any holes cut?

Any other thoughts?

[irv]

you can get cheap cool boxes for <£10
doing anything with polystyrene would be very temporary as it will fall apart.
you wont be able to put any pressure on the walls to make a seal
cutting a nice hole will be difficult
there is probably about £2 worth of polystyrene there .

i could probably go on with other thoughts

[chris2012]

I definitely wouldn't bother, polystyrene is so flimsy, it will just fall apart.

[lord groan]

Agree with the others, the expanded foam will be impossible to clean, and it'll crumble quickly, not to mention I'm not sure how food safe it really is.
That said these are exactly what I used for the insulation on my first mash tun. I got a mango chutney barrel free from my local restaurant by asking for it at the kitchen door, then I asked at my local chinese supermarket when I spotted a delivery of these big white polystyrene boxes, they just throw away these boxes after emptying them! With a modest amount of cutting I made a full enclosure for the mango barrel then backfilled the gaps in the corners with builders expanding foam after wrapping the barrel in plastic sheet so I could be certain of removing it from the foam enclosure easily.

As you can see it's really easy to spray too much foam down the gaps!
I ended up with 2 halves enclosing the bottom 3/4's of the barrel and a 3rd box cut down to act as a lid, all foam filled and trimmed off surplus. In use it lost around 1 degree over a 90 minute mash as long as I preheated it.

[Pinto]

As others have said, it wont make a tun itself - but could work well as insulation for one....

Use it to insulate something like one of the PP "storage boxes" you can buy -this kind of thing

[JamesF]

I'm not convinced it would make a good mash tun by itself and I'd be concerned about its food safety at mash temperatures. I see no reason why it shouldn't be robust though. I have a number of polystyrene beehives and they're pretty tough. You certainly wouldn't want to get smacked around the head with one.

James

[sbond10]

I think as an outer to a cheaper cool box tun it would be ok but not as a tun it's self