Soldering a leaky flask-bad idea?
January 15, 2008 5:05 PM   Subscribe

Thinking of solder to fix a broken flask. Tell me why I shouldn't do this.

A friend of mine at work has a flask that has split along one seam near the top (approximately a half-inch long gap, that is no wider than a fingernail at its widest point). Naturally this makes the flask leaky. I was thinking I could throw some solder on there, but would that leak horribly toxic chemicals into any flask-carried drinks?

Alternate, possibly as bad solution: Hot glue gun? I suppose as a last-ditch effort I could get some non-toxic elmer's.
posted by ®@ to Sports, Hobbies, & Recreation (12 answers total)
Silver solder.
posted by weapons-grade pandemonium at 5:07 PM on January 15, 2008

Silver solder that is used for plumbing would be ok.
posted by kuujjuarapik at 5:09 PM on January 15, 2008

I've used cyano acrylate super glue in the past for things like this. Once it's dry, it doesn't pose a health hazard and it won't wear off in the dishwasher. Don't know how it stands up to alcohol, though, if it's the kind of flask that you'd use for "warming up".
posted by fvox13 at 5:18 PM on January 15, 2008

Silver solder, yup, but you want the cadmium-free type.
posted by Pinback at 5:24 PM on January 15, 2008

What sort of flask? If it is a thermos type flask, there's not much point, as the vacuum between the two skins will have been lost, and it will be a shadow of its former self...
posted by Brockles at 5:32 PM on January 15, 2008

Response by poster: It's a cheap flask (he just got it). Pretty sure it's not a thermos. This has been really helpful!
posted by ®@ at 5:39 PM on January 15, 2008

Normal solder is has a lot of lead in it, and should not be used on anything that will contain food or drink.

The question of silver solder, and soldering at all, is whether you could get a satisfactory result. Can it be heated enough? Will the solder actually grip? Will heating damage it? Can you fully plug the leak? Will it be ugly afterwards? (It's almost certainly impossible to plug a gap the width of a fingernail using solder alone.)

Honestly, it's probably cheaper, easier, and more satisfactory just to buy a new one.
posted by Steven C. Den Beste at 6:12 PM on January 15, 2008

I think they meant the thickness of a fingernail, Steven.

Otherwise it'd be called a 'bloody great hole' rather than a 'crack'. You could fill a crack that size with solder, that's for sure.
posted by Brockles at 6:34 PM on January 15, 2008

how about epoxy?

<humor>there's this magic stuff called JB-Weld....</humor>

regular 2-part epoxy might be able to do this
posted by ArgentCorvid at 7:08 PM on January 15, 2008

That's not even funny. That's the same epoxy that's holding my Oldsmobile together. If it can survive 3 years worth of hot/cold antifreeze cycles ...
posted by IronLizard at 5:46 AM on January 16, 2008

Electronics solder has lead, plumbing solder generally does not. Silver solder is something completely different and will be harder to work with than plumbing solder.

JB Weld is probably the easiest way to fix it, but if you're set on repairing the metal, you want to look into brazing.
posted by electroboy at 8:02 AM on January 16, 2008

If you are thinking of brazing and using silver solder, there is no way a regular butane brazer torch would get the metal hot enough for the solder to melt. You'd need several torches or an acetylene torch, otherwise the rest of the metal would "steal" the heat from the crack area.

Epoxy sounds like a quicker and easier solution.
posted by rmless at 8:58 AM on January 16, 2008

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