I just cut open an old inner tube I had laying around and noticed there is a white powder in there. What is it? Why is it there?

1 Answer 1


It is talc, and it is used in the tube making process to prevent the inner tube rubber from sticking to itself.

  • Thanks. Do you know how I can test if it's talc? Commented Feb 9, 2015 at 4:26
  • 2
    You'd have to do some chemistry, but I don't know the particular chemical tests you'd have to do off hand. You could email the tube manufacturer as well. Technically, I suppose it could be cornstarch as well, though talc is the traditional material.
    – Batman
    Commented Feb 9, 2015 at 14:13

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