I watched several times “How to build a mash tun” video in this site and I decided to build mine just like i’ts showed in that video. So after buying a coleman cooler and a rubber mini keg bung I have to face an unexpected problem I hadn’t taken into account: how to bond the rubber bung in the cooler. I’m not sure but I think the cooler is made by polypropylene (or high density polyethylene). Has anyone got any idea? Thank you very much.
DAP all-purpose adhesive sealant. 100% silicone. “Aquarium Safe.” This stuff works really well.
Did you find the plans here? - dennybrew.com
Why do you need to bond the bung to the cooler?
On mine, I just stuffed it into the hole where the spigot was and it fit perfectly. No leaks, no fuss. Less than a five minute conversion.
Yes, of course. In the picture I see something like a rubber mini keg bung bond with something grey (glue or silicone) http://hbd.org/clubs/cascade/public_html/dennybrew/bung2.jpg
I don’t dare… Yes, I put the bung into the hole and it fit perfectly but I considered (cause I’d already watched it in the video) bonding the piece to the cooler… Thank you very much.
I mashed in my tun over the weekend with no leaks.
I had previously de-converted it for a party (needed a water cooler) so I had to re-convert it on Monday morning. Changing it back took minutes.
If it doesn’t leak, you don’t need the sealant. If it leaks, that’s a different story.
I never noticed the glue there. I’m sure Denny will chime in, but like Joe, I don’t know if you’ll need it.
It’s just new so I’m gonna test it in order to know if it leaks or not…
I’ve also thought about keep the spigot and put a silicone pipe inside, instead of the mini keg bung. I have a doubts: the hole is hexagonal so I don’t know if silicone pipe is gonna fit there perfectly. Sometimes I’ve drilled the lid of a bottle to get a blow-off system in a “disposable” fermenter and although the hole wasn’t a perfect circle, silicone adjusted perfectly and there wasn’t any leak.
Thank you very much.
I’m looking forward to hearing from him 
Sometimes you don’t need to use any sealant at all. If you do, just use a good silicone sealant/adhesive.
I said the hole of the spigot was hexagonal, but it’s a mistake: it’s circular, although the inner part is hexagonal. I’m gonna try to keep the original spigot and put a silicone pipe 12 mm (I have to order it; yesterday I tried with a 10 mm pipe and it doesn’t ajust perfectly).
Yesterday I tried to fix the bung into the hole and I found it a bit weak, I mean, it’s easily removed…