Author Topic: how to bond rubber and plastic  (Read 696 times)

Offline larsmm

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how to bond rubber and plastic
« on: September 09, 2015, 08:49:44 AM »
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.
« Last Edit: September 09, 2015, 01:51:11 PM by larsmm »

Offline Chris S

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Re: how to bond rubber and plastic
« Reply #1 on: September 09, 2015, 02:15:14 PM »
DAP all-purpose adhesive sealant. 100% silicone. "Aquarium Safe." This stuff works really well.

Offline Stevie

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Re: how to bond rubber and plastic
« Reply #2 on: September 09, 2015, 02:49:48 PM »
Did you find the plans here? - dennybrew.com

Offline Joe Sr.

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Re: how to bond rubber and plastic
« Reply #3 on: September 09, 2015, 02:58:31 PM »
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.
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Offline larsmm

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Re: how to bond rubber and plastic
« Reply #4 on: September 09, 2015, 03:10:44 PM »
Did you find the plans here? - dennybrew.com

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

Offline larsmm

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Re: how to bond rubber and plastic
« Reply #5 on: September 09, 2015, 03:20:50 PM »
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.

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.

Offline Joe Sr.

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Re: how to bond rubber and plastic
« Reply #6 on: September 09, 2015, 03:24:49 PM »
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.
It's all in the reflexes. - Jack Burton

Offline Stevie

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Re: how to bond rubber and plastic
« Reply #7 on: September 09, 2015, 03:35:26 PM »
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.

Offline larsmm

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Re: how to bond rubber and plastic
« Reply #8 on: September 09, 2015, 03:43:59 PM »
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.

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.

Offline larsmm

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Re: how to bond rubber and plastic
« Reply #9 on: September 09, 2015, 03:46:37 PM »
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.

I'm looking forward to hearing from him  ;)

Offline denny

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Re: how to bond rubber and plastic
« Reply #10 on: September 09, 2015, 04:09:06 PM »
Did you find the plans here? - dennybrew.com

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

Sometimes you don't need to use any sealant at all.  If you do, just use a good silicone sealant/adhesive.
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Offline larsmm

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Re: how to bond rubber and plastic
« Reply #11 on: September 10, 2015, 08:28:36 AM »

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.


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).

Offline larsmm

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Re: how to bond rubber and plastic
« Reply #12 on: September 10, 2015, 08:31:59 AM »
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.

Yesterday I tried to fix the bung into the hole and I found it a bit weak, I mean, it's easily removed...