How to plug a water leak, food-safe?

February 8, 2011 5:46 PM

My stovetop espresso maker has a small leak. I don't think returning it will help me. Are there any recipes for food-safe 'stop leak' compounds?

The coffee maker is a Vev Vigano Carioca in stainless steel. The leak is in the water tank, around the pressure relief valve (not through it). Viewed from the inside, it seems the brass pressure relief valve was installed by being 'punched' through the stainless water tank, leaving a rough, splayed surface. I imagine there's a small gap between brass and stainless where steam / water can escape.

The place I bought it from is a ways away, and it doesn't seem possible to test coffee pots for leaks before buying, so I don't think returning it is worthwhile.

Is there any solution I could buy/make that would do a decent job of sealing the tiny leaks around the pressure valve? Of course, whatever I use has to be food safe (no automotive products!).

posted by anthill to home & garden (10 answers total)

sugru?
posted by brainmouse at 5:50 PM on February 8, 2011 [1 favorite]

From the pictures it look like there is no plastic near it. Could you get it brazed at your local jeweler? Gold and silver brazing material is completely food safe.
posted by Confess, Fletch at 5:59 PM on February 8, 2011

Best fix: getting a skilled brazier to seal the leak. Next best? A steel epoxy like JB Weld comes to mind: there's a discussion here about a similar repair which goes into whether it's food-safe, and the WaterWeld putty is approved for repairing water pipes. (Aquamend is a similar product.)
posted by holgate at 6:06 PM on February 8, 2011

Great answers, thanks. Two limits I didn't think about:

1) The boiler may heat to over 300F (thanks to gas stove and above-atmospheric pressure), right at the limit of AquaMend.
2) Also, it will go through thermal expansion cycles (of dissimilar materials, natch) so an adhesive will need to be somewhat flexible.

Brazing sounds great, wonder how much that would cost, and if it would be possible to do it without destroying the spring-loaded pressure valve.
posted by anthill at 6:52 PM on February 8, 2011

My experience with those pressure relief valves is that they're threaded (hence the nut-like face on the exterior). Is it possible that the "punched" hole is actually threaded on the inside surface to accept the valve? Have you tried tightening it with a wrench?
posted by pullayup at 7:23 PM on February 8, 2011

Here's a picture, though those look like they're for the classic cast-aluminum style.
posted by pullayup at 7:31 PM on February 8, 2011

It's not clear how the valves seal from the pictures. There are 2 possibilities-
1. Taper thread. The valve screws into a thread in the lid. Tighten it gently. A little PTFE tape on the threads will help.
2. Face seal. The valve seals on a flat either under the hex flange or at the end of the valve. The valve may either screw into the lid, or pass through a hole in the lid and have a nut on the inside. Clean up the faces with a light abrasive (toothpaste may work) and tighten down. Replace any rubber or copper washers.

First step is to take it apart.
posted by BadMiker at 11:50 PM on February 8, 2011

Yes you can in fact get the valve out and in with a wrench, it is threaded. I suppose that during manufacture, the hole for the valve is first punched into the side of the water tank, then threaded and then the valve is screwed in. It's a tight fit; there is no seal of any kind. If the punching went wrong, there will be a leak.

A few considerations:

A leak of that kind is untypical for this type of pot and your chance that you pick up another one in the shop that has the same flaw is small. It is also a good reason for returning the pot. As soon as there are wrench-marks all over it, however, a shopkeeper might have another view about this.

That said, if it looks like you'd be easily able to screw the valve in another quarter turn or so, I would go for it.

But: if the leak is small, it unlikely seriously impairs the function of your pot. Also, it will probably eventually seal itself with residue. If your pot works well otherwise, you could just accept it as a quirk...

The vastly more annoying two possible problems with this model are
* new rubber seals that are not yet worked-in enough to seal properly and leak steam off the sides of the pot.
* embedded coffee grains, causing the same effect (these can simply be scraped off with a spoon handle or a paring knife tip).

Steam leaking out of the sides considerably decreases the inner pressure, sometimes to the point that the pot stops functioning properly; you'd have to boil the water full blast in order to process any coffee at all, and for a long time; the result is bitter and will have picked up a lot of the rubber taste of the seal.
posted by Namlit at 4:12 AM on February 9, 2011

Tried a 9mm wrench, applied as much force as I could with hands only. Didn't budge.
posted by anthill at 8:38 AM on February 9, 2011

End result: residue sealed up the leak after a few months. The Sugru came in handy for some auto repair though!
posted by anthill at 6:42 PM on May 23, 2011