Will a “pot-watcher” be good for keeping fermenting vegetables under liquid to stop them going moldy?

The pot-watcher comes well packaged

Usually I keep vegetables submerged with a combination of a shot glass and a segment of core or outer leaves of cabbage. This technique is pretty good but not in all cases, like when using chinese leaf lettuce (napa cabbage) as it doesn’t have much of a core and the outer leaves aren’t very rigid.

I thought that there might be other food accessory products out there that I could use.

So I saw these “pot-watchers” on Amazon and thought that they might be useful.

Buying the product

They are described as “5 Metaltex glass milk saver boil boiling water alert pan pot watchers”, which isn’t the most illuminating title, I suspect they were just stuffing as many keywords in there so that their product could be found.

The cost, in October 2016, was £8.99 with free postage which works out as about £1.80 each.

They are sold by MightyHousewares who, on the date I bought, had a 4.9 stars rating over the previous 12 months out of 8,694 ratings. So a pretty safe bet. They are a UK company based in Wembley.


The product came well packaged, with FRAGILE marked tape all round it so the posties know to be careful of the glass contents.

On opening the box there was plenty of bubble-rap in evidence to stop the glass from getting banged about and broken.

The instructions for using the pot-watcher

Each pot-watcher comes on a separate card which it is securely laminated to.

On the front of the card is the makers name “metaltex”. An odd name! Turns out it’s a Swiss company founded in 1945 who started out making wire strainers, whisks and the like; now it’s a huge international company.

Also on the card is a diagram and a photo of a pan of boiling water. The photo to show what the pot-watcher is used for and the diagram to explain how.

What is a pot-watcher?

The actual use of the pot-watcher is to alert you when any liquid you are heating in a pan starts to come to the boil. It does this by vibrating on the bottom of the pan as more bubbles are produced as the temperature rises.

A pot-watcher

Will the pot-watcher fit in my jars? Yes!

On the back of the card are the instructions of how to use the pot-watcher in all the different languages. In English it reads:

Boil over preventer
Warns you when liquid is beginning to boil, make of hygenic and heat proof glass. Just place in bottom of Pan and wait till it starts to sound.
Make sure that the disc has cooled down before washing it

The pot-watcher is well packaged on it’s card, sealed from the outside world and contamination, vacuum packed with a plastic covering round it so you will need a pair of scissors to cut it out.

The product

The product itself is nice and chunky, it’s a solid piece of glass weighing in at 78g.

It feels quiet sturdy which I guess it has to to survive the vibrations in a pan of boiling water. You don’t want broken glass in your milk!

The pot watcher fits in my wide mouth jars

It’s a dough-nut like shape, a really skinny dough-nut with a big hole, except the hole isn’t a hole it’s solid glass.

It’s just over 3 inches in diameter, that’s about eight centimeters, and it’s a centimeter thick on the thickest part the outer rim.

The outer rim is cylindrical and of the diameter of about 1 cm.

The pot-watcher is too big for for the narrower necked kilner jars

In one part of the rim there is sort of a pinch were it gets thinner probably to allow bubbles to escape to make it vibrate in the pan.

Using the pot-watcher in the fermentation process

So I didn’t buy the pot watcher to watch pots!!

I bought it to use to hold down fermenting vegetables in jars, I wanted something disc shaped, solid and preferably made of food grade glass so the pot watcher seemed ideal.

The first test is: does it fit in the jars I use for fermenting? I have various sizes some with narrow necks and some with wide necks.

The pot-watcher didn’t fit in the narrower necked jars but it did fit the wide ones. Result!

The wide necked jars are better anyway, because it is easier putting the veg in them than the narrower ones.

A pot-watcher holding down some kimchi

A practical example

How was it going to work in practice?

I had some fermenting veg on the go, some kimchi which I had made recently

I had two lots one in a narrow neck jar and some in a wide necked jar, you can see in the image that the pot-watcher is too wide for the first one.

But in the wider clip top jar with a wide neck it would fit.

I’d used my usual method of keeping the veg submerged using cabbage cores, outer leaves and a shot glass.

I removed the shot glass and inserted the pot-watcher, it fit perfectly, and pushed the veg down under the liquid as I closed the lid down over it and the shot glass.

This is exactly what I wanted. Perfect!

I can also stack them as well which is going to be useful because I’ve been over filling my jars when doing kimchi. I’ve been getting overflows. Kimchi seems to produce more liquid than sauerkraut while it’s fermenting, so I need to give it more head room in the jar to expand.

With the pot-watchers I can stack them above the veg and leave more space for liquid.


Yes, that’s a really good buy for my purposes.

I can use the pot watchers as I thought for holding veg under it’s liquid in fermentation, and, I can stack them to allow for more expansion.

And they are food grade glass. You see quite a few people using plastic bags on top of their ferments but I didn’t want to do that because I was worried about chemicals leaching out of the plastic. I’m not usually that worried about food in plastic containers but in the fermentation process the environment becomes quite acidic so I wanted to be more cautious and glass seemed like a more inert material as far as I know.

And they are cheap too. Good buy!

PS. I’d also ordered some Sterilock Fermentation Weights for the same purpose, they arrived shortly after I did this review.

Sterilock Fermentation Weights

So at last my Sterilock food fermentation weights have arrived after waiting 9 days.

I ordered on Amazon at the same time I ordered the pot-watchers.

They came directly from Sterilock. Sterilock charges £2.80 post and package, but despite this they took a week longer to arrive than the pot-watchers from MightyHousewares who provided free post and package.

So compared to the pot-watchers these are a lot more expensive, working out at £4.26 each whereas the pot-watchers are £1.80 each.

They arrived in an envelope rather than a box and in a second plastic bag and wrapped in tissue paper. So not as well packaged as the pot-watchers that came in a box and were well protected by bubble wrap. But I think the packaging was adequate, the only way the glass weight would get broken is if they had a direct hit from the equivalent of a brick, which is probably unlikely in the post, I would hope! And the environment could probably do with less packaging too.

Sterilock Fermentation Weights

The first thing that strikes me is that the Sterilock fermentation weights are tiny compared to the pot-watchers and they don’t weigh very much just 32g compared to a pot-watchers which are around 71 grams.

The pot-watcher is a lot bigger than the Sterilock weight and and is twice as heavy, so I’m thinking at the moment that the pot-watcher is a better bet for holding down the veg in a ferment.

The fact that the Sterilock fermentation weight is smaller gives it one advantage, though, in that it fits into the narrower necked fermentation jars, so I will probably be using them for smaller scale fermentations.

I also like the pot-watchers dough-nut shape better too. It will work better with my shot glass method of holding down the veg, as the shot glass will be contained by the pot-watcher’s rim and not slide about.

The Sterilock weight is lens shaped. It says in the add that the “Domed Surace Of The Weight Allows Clear Magnified View Of Fermenting Food”. Do I really need that? I’m not sure, we shall see I suppose. And the shape may slip around in the jar with my shot glass method.

The Sterilock weights are “BPA free”. BPA is a chemical product that is used in the some plastics and some people have concerns about it, though I don’t know what those concerns are. But seeing that this product is glass - as far as I know BPA isn’t used anyway so the “BPA free” notice is probably there just for reassurance.

The weight is also described as “crystal” rather than glass, and some crystal contains lead. Which makes me a bit wary. Someone has asked on the Amazon page if it does in fact contain lead and Sterilock answer: “the material is highly polished glass and contains no lead.”

So for me the pot-watcher wins, it’s bigger, it’s sturdier and it suits the sort of fermentation that I want to do and it’s cheaper and arrived a lot quicker than the Sterilock weights, so yes my vote is for the pot-watcher.