High Temperature, Food Safe Sealants

Jelly · 3 Mar 2021

Recently got given a dishwasher with a small but noticeable leak which the previous owner had not been able to trace.

After running it a couple of times jacked up on blocks with a bucket to catch the drips, and taking Thermal Images with my phone (actually a useful feature, which I totally wrote off as a gimmick) I've traced it to a tiny rubber grommet which fits into a hole in the plastic tub bottom where it joins the stainless steel sides of the tub.

Those grommets are unavailable as a spare, or a commercially available part, so I need an alternative sealant.

However, whilst I can find lots of sealants suitable for high temperature service in a caustic environment, and lots of food safe sealants, I'm struggling to source a product which will meet all three requirements.

Any suggestions?

Woody2Shoes · 4 Mar 2021

I had a similar problem with a failed gasket in the base of our german-designed dw. I used neutral-cure silicone and none of us have died yet. I think that most silicone sealants have fungicide in them which is probably fairly toxic - although I'm sure we get lots from other sources.
An alternative might be to get hold of a piece of medical-grade silicone tubing and carve your own. What are the actual dimensions you're after? You can buy small o ring seals for food use Complete Kegging Companion Seal Kit

Terry - Somerset · 4 Mar 2021

It may not be technically right but if it is but a very small grommet the risks of contamination via cleaned crockery must be very low.

If in doubt, do the repair and run it empty for a couple of cycles!

disco_monkey79 · 4 Mar 2021

How tiny is tiny? A well-known auction site has various listings for grommet selection packs in assorted sizes.

Jelly · 4 Mar 2021

Might have fixed without sealant (or buying anything).

Speaking to a friend who works in the Teflon coating industry last night, he reminded me that PTFE self amalgamates under even fairly moderate pressure, and suggested I just crush a bunch of plumbing tape in a vice.

Had a crack at compressing loads of PTFE tape together to form a wee block, then cut out a little tapered wedge with a scapel and forced it into the offending gap with tweezers... No idea if it will work long term, but it held up OK last night after tea, so might all be grand.

@Terry - Somerset & @Woody2Shoes

That was (and remains) a consideration, but all i have in the workshop is a butyl rubber gutter sealant, which I'm definitely not trying... so given that I'd have to buy something, I figured it was worth trying to find the "Proper" product.

The leachability of dangerous chemicals not especially worrisome to me (after years of low-level occupational exposure to far worse, why worry?), but I really don't want to end up affecting the taste of my food, that would be a tragedy.

Anyhow if the leak comes back and I can't find something "proper" it's either silicone sealant or a little tube of high-temp epoxy...

@disco_monkey79

By tiny we're talking about a 1.5mm by 4mm rectangular hole, which is just all all round awkward thing to get a seal for... No idea what purpose the holes could even serve in the design.

Unfortunately it just happens to be placed such that it's right where the splash back from jets hitting plates in the rack will come down with some force, meaning that it does actually leak enough to be awkward (about 50-100ml for a full wash cycle, I put a jug under the drip to measure it).