Mashtun - what sealant should I use?

[bonzombiekitty]

I tried building myself a mashtun last night out of a cooler. The problem is that it still leaks slightly around the seal. I'm going to try some different gaskets to see if I can make the seal better - it might just be that the gasket that was in the cooler itself just sucks, but I'd like to know what sort of sealant I should use if I need it.

Would your basic gorilla glue work? What about silicon? Or is there something else I should use?

 

[ExHempKnight]

Food-grade RTV. No Gorilla Glue.

 

[hal2814]

Silicone will work but it will likely wear out over time. I put a layer of 3M 5200 on to stop the leaks and have a layer of silicone over that. It's probably overkill but NOTHING gets through 5200 though it's probably toxic to some extent (hence the silicone over it).

 

[g-star]

I had the same problem. I replaced the rubber gasket that came with the cooler and it solved the problem immediately...doesn't leak a drop.

 

[bonzombiekitty]

I had the same problem. I replaced the rubber gasket that came with the cooler and it solved the problem immediately...doesn't leak a drop.

Problem is that hole is 1", and there doesn't seem to be a gasket at the hardware store that fits. I'm using a 3/8in nipple and have some o-rings that fit around it, but that's just an extra layer between the fittings and the washers.

 

[bonzombiekitty]

Silicone will work but it will likely wear out over time. I put a layer of 3M 5200 on to stop the leaks and have a layer of silicone over that. It's probably overkill but NOTHING gets through 5200 though it's probably toxic to some extent (hence the silicone over it).

I don't care much about it wearing out over time. I don't mind having to take it apart and re-apply here and there. Which type of silicone did you use? Did you just use basic silicone, like the silicone used for aquariums? Or did you go the full food-grade rtv route (which looks like that would have to be a special order)?

 

[Bobby_M]

1/2" nipple will get you closer to 1"

 

[bonzombiekitty]

1/2" nipple will get you closer to 1"

It's not the nipple size that is the issue. It's finding a gasket that's big enough for the hole in the cooler.

Doing fitting -> o-ring -> washer -> gasket should work as the washer should compress the gasket around the hole in the cooler making a seal.

I couldn't find any gaskets at HomeDepot or Lowes that would be big enough, at least at first glance.

 

[g-star]

Problem is that hole is 1", and there doesn't seem to be a gasket at the hardware store that fits. I'm using a 3/8in nipple and have some o-rings that fit around it, but that's just an extra layer between the fittings and the washers.

I went out and bought the same cooler brand new. Took out the rubber seal and put it in my mash tun. Then I took the leaking rubber seal and put it back in the new cooler I just bought and returned it to the store.

Problem solved. Maybe this will work for you if you can find the same cooler in the store?

 

[hal2814]

I don't care much about it wearing out over time. I don't mind having to take it apart and re-apply here and there. Which type of silicone did you use? Did you just use basic silicone, like the silicone used for aquariums? Or did you go the full food-grade rtv route (which looks like that would have to be a special order)?

I had a spare tube of some GE Silicone sealant for doing stuff like kitchen and bathroom seals that was marked non-toxic on the tube so I just used that.

 

[bonzombiekitty]

I had a spare tube of some GE Silicone sealant for doing stuff like kitchen and bathroom seals that was marked non-toxic on the tube so I just used that.

Yeah, the aquarium stuff I've seen is marked as safe for food contact. But I was worried more about the temperature - aquariums don't normally go up to 170 degrees.

 

[OHIOSTEVE]

I used the aquarium sealant on mine and it works fine after 4-5 batches so far. ANYTHING that can be used inside an aquarium is probably safe for us to use. I swear an angelfish will die from contacting ANYTHING.

 

[sagnew440]

I used aquarium silicone sealant. I got it from Petco or Petsmart. I found some food grade rtv on the internet but didn't feel like paying more for shipping than the rtv cost. I think its only temp rated to like 140's or 150's but It has worked good so far(1 year) with no taste difference or side effects( no third eye yet)

 

[bonzombiekitty]

I used aquarium silicone sealant. I got it from Petco or Petsmart. I found some food grade rtv on the internet but didn't feel like paying more for shipping than the rtv cost.

Yeah, I noticed that too. The tube costs like $4, which is reasonable, but shipping is like $5.50.

 

[hal2814]

Yeah, the aquarium stuff I've seen is marked as safe for food contact. But I was worried more about the temperature - aquariums don't normally go up to 170 degrees.

Not sure about the aquarium stuff but my bottle says it's good to like 300F or something. I just remember it was WELL above what was required.

 

[tunoffun]

MY LHBS sells silicone rubber o-ring gaskets alone... the same red/orange ones you find included in the no-weld bulkhead kits. I'm sure other places carry them as well. Not sure on the sizing, but they had two different sizes. Both had the same internal diameter (which fits a 1/2" pipe nipple perfectly), but the thickness differed. I used the really thick version. The only place I use the gasket is inside the tun. No need for one outside if you get a good seal. Matter of fact, IMO, putting one on the outside will only serve to disguise the fact that you don't have a good seal inside. And if you don't have a good seal inside, you risk liquid seeping in between the plastic layers.

So inside the cooler, I have a 1/2" SS nipple poking through, the gasket, a flat SS washer sized to fit the nipple ID precisely, and then a locknut. Not sure what the actual length of the nipple is, but it's the next size up from a 'close' fully threaded nipple (the non-threaded portion is approx 1/4"). The washer was found at Ace hardware, and it actually is just a hair too small to fit the thickest part of the nipple. I took a dremel and opened it up so it just barely fit. The idea is to have as small a gap as possible.

On the outside, I have 3 or 4 similiar washers (only not SS for cost savings), and then the ball valve. Once again, the ones I found were just a hair too small & I opened them up. I use multiple washers to get the offset I need for the lever so it could fully close w/out contacting the cooler body, and also to locate the nipple so on the inside of the tun, the gasket seals mainly against the non-threaded (center) portion. The OD of the washers is what will just barely fit inside the recess in my cooler (your cooler may vary... mines a rubbermaid 10g).

I have my tun & HLT built this way, and they're both rock solid. Don't leak a drop.

Sorry - a simple picture probably would have explained all this alot better. But I don't have a camera at the moment.

ETA: just for clarity, this is with the stock rubber gasket removed (and with it removed, you can see how liquid could seep into the cooler body if you don't get a good internal seal.