I bought silicone ice cube forms and when I used them something white swam on the water. I guess some silicone that dissolved from the form.

First I made ice three times and threw it away, but the problem persisted. Then I tried to put them in the dish washer. Now I bought another product from a different manufacturer and the problem is even worse.

(I am NOT 100% sure if they may still be products from the same factory or made in a similar way, but I explicitly tried to buy another product)

Are silicone forms just crap, am I doing something wrong, or is there a good way to clean them before the first use?

Picture of the dirt swimming on the water

I do not have the problem using the same tap water with the hard plastic ice cube maker that came with my fridge. The general water quality here is quite high and I even use the water with a sodastream and making tea in the same glasses and it looks perfectly clear.

Before freezing the water looks clear as well an I do not see such dirt even when I let a glass of water stand somewhere.

Update: I made an experiment by freezing one form with and one without lid. Here is an image of the forms and the lid:

silicone forms

The blue one was used without lid. They seem to be both silicone and the lids are all the same, only the forms have different colors.

The result after dissolving all cubes looks like this: pictures of the water of the dissolved ice cubes

Left: blue form without lid (Little dirt, but still too much)
Right: white form with lid (Larges flakes of some dirt)

The cubes in the open form were quite easy to remove and well-separated. The lid stuck a bit on the cubes and I needed to break the cubes apart by bending the silicone, because the lid hold the water surface flat.

The open form stood on the closed one.

Update 2: Boiled water has the same problem. I'll try a water filter next.

Update 3: Water hardness as published by my water supplier:

  • Hardness 4,7 – 8,1 °dH (soft)
  • Magnesium 5,2 – 9,0 mg/l
  • Calcium 24,6 – 43,5 mg/l
  • Natrium 11,3 – 21,9 mg/l 200 mg/l
  • Chlorid 23 - 39 mg/l 250 mg/l
  • Nitrat 10 - 21 mg/l 50 mg/l
  • Uran < 0,0002 mg/l 0,01 mg/l

Update 4: Same result with the water in another city (unknown hardness). In some of the forms white sediments after the water rest dried. Next I try a water filter.

Update 5:

I tried a water filter and got the same result.

Using a water filter I still get white flakes like in the right glass after melting all 24 ice cubes of the new form (not the one pictured above, but also silicone) with lid.

  • 1
    If you make ice in other vessels (regular ice trays or in a cup), do you have the same results ?
    – Max
    Sep 22, 2020 at 11:40
  • @Max No. I always had ice cubes from a normal tray and bought the silicone tray just to have more cubes. I added this to the question now.
    – allo
    Sep 22, 2020 at 13:37
  • Try one more experiment, swap which tray gets the lid & test again. If the one without the lid gets the scum, then the only conclusion I could arrive at is that 'something' in the fridge is responsible.
    – Tetsujin
    Sep 26, 2020 at 7:45
  • The one with the lid was worse. I am currently testing with the water of another city. One of the newer forms (not in the image) had fewer scum in the water, but still a bit. The ones in the image will be frozen now (with lid and in another fridge) and I'll test them later. My own fridge is very new (about 3 months). I think yet another possible problem could be bad pipes on the last few meters. I am not aware of this, but I also cannot exclude that there is a pipe with calcium sediments or a similar issue somewhere either.
    – allo
    Sep 27, 2020 at 8:35

4 Answers 4


Silicone does not dissolve in water.

The scum you see floating on the top looks very much like lime-scale. This is in your water supply. It will also give you an encrusted kettle & white/grey blobs stuck to the nozzle of the hot tap after some time.

You could try distilled water, or invest in some kind of hard water filtration system. As mentioned in comments, using cooled, boiled water may also help a little, as the boiling will drop some of the calcium out of the water… & stick it to your kettle element instead.

Many places in the world you can enquire with your local water company as to how hard your water supply is - how much calcium, basically - & they will advise on softening methods.

  • The Water quality here is quite high. I would consider if making ice cubes could lump together things in the water, but I do not have the same problem with a hard plastic ice cube maker.
    – allo
    Sep 22, 2020 at 13:32
  • 5
    "Water quality" is not in question. Water hardness is. One does not equate to the other. See coffee.stackexchange.com/a/5267/7496 for another take on it & refer to your water authority to see what the local hardness is where you live. Silicone is an almost inert substance. It does not dissolve in anything you could find in a kitchen - en.wikipedia.org/wiki/Silicone - so whatever is the difference between your two ice-cube-making materials/methods, silicone is not the cause.
    – Tetsujin
    Sep 22, 2020 at 15:20
  • 2
    There's potential it could have had a layer of release agent which needed washing off, but that wouldn't survive soap & water, let alone the dishwasher.
    – Tetsujin
    Sep 22, 2020 at 15:20
  • Here in germany the actual water quality is always drinkable when not explicitely stated otherwise. By bad quality I mostly mean calcium carbonate (I hope thats the right word here. I mean the component that requires you to put vinegar into the water boiler), which may look like this when it for example would dissolve when boiling the water. But I have tasty water from a soda stream here and crystal clear tea every day, so I would almost exclude this, except when it could concentrate such substances when freezing the water.
    – allo
    Sep 23, 2020 at 12:07
  • 1
    @allo It's not about "drinkability" either. Hard water can be tasty and crystal clear, particularly after boiling.
    – Sneftel
    Sep 24, 2020 at 8:34

Hmm it looks like ot could be from the ice, not the silicone. Have you tried filtered or mineral water as a comparison?

  • Mineral water might be worse than tap water, but cooled boiled water would be worth a try
    – Chris H
    Sep 21, 2020 at 14:44
  • Filtering the water seems to make no difference. I bought a simple water filter and the flakes on the water are the same. I already was believing it must be the water, but if it is in the water then it's something that is not filtered out.
    – allo
    Sep 29, 2020 at 17:47

Looks like it is from your water containing certain (non-harmful) elements and not the silicone.

There are 2 solutions for you to try to get better ice cubes.

  • Try using bottled water and seeing the difference
  • Try boiling the water first. This can help remove the impurities and should give you crystal clear bubble-free ice cubes.
  • I start an experiment with boiled water now. I update the post with the results later.
    – allo
    Sep 24, 2020 at 10:49
  • Boiling does not help. I will try water filters. And maybe test with the water from another region where I am sometimes.
    – allo
    Sep 24, 2020 at 20:45

Supposedly from what I have read, the minerals in the water calcify and stick to the silicone, and is supposed to be completely harmless. For me, if it's harmless, I don't care what it looks like and just run with it. You could try washing using a Zero water filter to make the ice and see if that helps. It supposedly removes particulates completely.

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