I've notice that after we wash & air dry our silicone nipples, frequently they will have a light whitish kind of film on the inside. This film survives boiling water sterilization too. I would then have to wash it again with a lot more soap to remove this.

Why does this happen? Is it from the milk fat?

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  • Wash/soak in vinegar and it should go away :)
    – Swati
    Commented Feb 23, 2012 at 3:16
  • If you wash after sterilizing, then it is no longer sterile. But you already know this, of course. Commented Feb 23, 2012 at 15:17
  • @TorbenGundtofte-Bruun We only sterilize once in awhile...the other times we just wash with hot soapy water.
    – milesmeow
    Commented Feb 24, 2012 at 17:14

5 Answers 5


The milk fat is easily washed away, so I would rule that out.

I think what you're seeing is the dried calcium of the tap water, especially if it seems powdery and can be rubbed off when dry. I think this is what user77907 means by scale. This is especially the case if your tap water is very hard.

You need not worry about these deposits: according to Wikipedia, the World Health Organization says that "there does not appear to be any convincing evidence that water hardness causes adverse health effects in humans."

I installed a water filter for drinking water (and for sterilization, coffee maker, etc.) in my kitchen, and all appliances as well as washed/sterilized items no longer have these deposits. If you're concerned about the purity of your tap water, I recommend this filter from APEC Water Systems; it's the best I could find, and many alternatives were much more expensive.

  • It actually is no powerdery, but filmy...let me see if I can get a picture.
    – milesmeow
    Commented Feb 22, 2012 at 19:33

If you are washing the bottle parts in a dishwasher it may also be any rinse aid. I've noticed a similar film after they come out of the washer. I simply give them a quick hand-wash with warm soapy water and it usually takes care of the film.


I think it's just scale. Nothing to worry about. Actually sterilization won't remove it but add some more...

  • I'd concur with the scale idea. I live in a very hard water area and frequently see the same thing on bottles & teats.
    – Jamiec
    Commented Feb 23, 2012 at 11:40

It is actually a combination of fat and scales. Clean it by shaking soapy water on the bottle and use a nipple brush to clean it. Sterilize after drying using RO water preferably.


I have tons of the nipples for Dr. Brown bottles and for the longest time I had all the cloudy nipples stashed away and even bought new ones. I found that placing them in a large glass, pouring in cocoa cola (non-generic) and stirrinh them around with a spoon works well.

Just stirring them around a little for a minute or two does the trick just as well as waiting longer periods (I used to soak them for 30 minutes.)

  • I have before and after pics to compare the huge difference... I don't know how to attach a picture tho Commented Jan 27, 2016 at 19:24
  • Click edit above, and then when editing there should be a picture icon (read through parenting.stackexchange.com/help/formatting).
    – Acire
    Commented Jan 27, 2016 at 20:16
  • 1
    Hello, and welcome to the site. This doesn't really fit the style this site prefers. We're not a clickbait blog; we're looking for well researched answers to questions formatted in a professional way. I don't think this is particularly helpful here, as it doesn't answer the question - "what is this" - and it seems like overkill in any event (if coca-cola is removing it, then it's easily removed by lots of other things). If that's not true - if coca-cola has some power that is not possible to replicate in something cheaper/simpler - please provide evidence to that effect.
    – Joe
    Commented Jan 28, 2016 at 14:58
  • 1
    @Joe - It could be that any acidic and effervescent liquid works, but the user does provide an answer. It may be that nothing else was tried. I, too, sincerely wish references were used more often in answers than they are, but there doesn't seem to be a reason to require one here more than the other answers offered. Maybe a meta question about references would help? Commented Jan 28, 2016 at 18:03

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