Silcone Sealer In Mash Tun?

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I am looking to put a manifold into an esky kicking around the house. It already has a drain hole.

I was thinking that I would use silicone sealer to make the copper exit point waterproof. Silicone sealant that you buy in bunnings does not specific food grade or even food contact. The closest seems to be 'aquarium safe'. I suppose that's alright if I drink like a fish.

Anyway, does anyone have any comments/experience with this approach?
I am sure if it safe for fish it would be ok , have to find some of this as well
Dow Corning 732 silicone sealant is the stuff you're after, food grade to 200oC. Can buy it in small toothpaste size tubes too. Should be able to find it in places like Blackwoods etc.
I use silicon in my mash tun, kettle and still. As long as it has completely cured,24 hrs, it is harmless.
Sorry to reawaken this thread but i have a problem. The problem occured when i was drilling and grinding a hole for a threaded pipe for my mash tun outlet. I didn't drill the hole perfectly square and as a result the pipe, washers and o rings aren't perfectly square. As a result there is a slight gap between the fibre washers and the wall of the tun. The following plumbing is based upon Sosmans description.

I bought some Selleys Aquarium sealant to fill the tiny gaps, but i don't know whether this is the best thing to use to seal between the SS washer and the threaded pipe, as it doesn't stick to brass. Is this fine to use? I saw a product called Stags sealant that is Food safe, should i use this? The problem with this is that i can't find any information as to whether it is fine for 70 degree temperatures.

Any help/advice would be much appreciated.


I used aquarium grade silicon in my first mash tun without problems.
I can't understand why it wont work on brass as I believe it would stick to it if applied while each part was completely dry.
I would NOT use stag as it is an old thread sealer and it has a real odour - even when it is dry.
Selleys aquarium silicon is what I use
Works well for me

ok.. bit of old plumbing info
You don't need to use aquarium silicon, plumbers roof and gutter silicon by law has to be food grade because of rainwater useage.
NEVER use bathroom/kitchen silicon as it has an acetic cure!!!
Silicon can more than handle mash and boil temps. We did a an experiment on the heat strength of silicon where we soldered 3 clouts and siliconed another 3 clouts to a sheet of iron, we then ran an oxy/ac torch over the back of the sheet.... the clouts that had been soldered all droped off, the siliconed ones all stayed strong and the silicon didn't even discolour.
.....or, use thicker washers! The red fibre ones only work if you have a close fit. I made much thicker washers out of a toilet cistern rubber replacement kit.
In my opinion the acetic acid curing silicone isn't a problem. Yeah it stinks and tickles your nose while curing but once it's cured there is not more acetic sell, it's gone and is well publicised to be gone too if I rememeber rightly. Cheers, Justin
My mash tun. two 20L pots joined with very smelly silicone and working perfectly for about 30 brews now.

dicko said:
I can't understand why it wont work on brass as I believe it would stick to it if applied while each part was completely dry.
I would NOT use stag as it is an old thread sealer and it has a real odour - even when it is dry.
Selleys states that it doesn't stick to copper and anything that has copper in it ie brass fittings.

I have a sample of Stags and will give it a test by applying it to a fittings and leaving it in some hot water to test it out. Apparently the old stags formula was not reccomended as it contained lead, but the New Stags container states that it can be used for gas, beverages and foodstuffs. Its being an absolute dog finding any info or specifications on this stuff.

Thanks for the heads up though Dicko, it does have a weird smell to it though. Like pine tar anti dandruff compound. Anyway thanks guys.


This follows on from the aboe post. Just conducted my first highly technical test of Stags Jointing paste. I placed a good drop of Stags on paper, thinned it out, and set it under a light to warm it up. Smell is evaporating somewhat, almost have to suck it in to get a good whiff of it. Second test was the lick test, i can taste only the slightest weird tarry taste. I will try a more technical test as identified above in the future.

Hi Kungy 1,
I am a real old fitter and when we used to use Stag you used metho to clean and prime the joints.
I am no longer in that trade (thank goodness) so I have no idea what happens today.
BTW, I still have a tin of Stag in my cupboard. Must throw it out one day!!! :D

Aquarium silicon has worked for me but if the actual leak is through the threaded fittings then I would just use thread tape.
Plumbers use this on our water systems both hot and cold so I recon it should be ok and I would imagine that this would comply with one of the many Australian standards that exist today.
Mate, you are right about the smell :eek:
I dont think I could come at a beer that smells like that :lol:
It would take over from the aroma additions at the end of the boil :D :lol: :chug:
All jokes aside, if it is approved for food, then use it.

Justin said:
In my opinion the acetic acid curing silicone isn't a problem.

...but it will "eat" many metals, hence one of the reasons why it is not used for roofing and as far as I know it is not food grade.