sand inside frame

[wearwell]

Stripping down to find why headset failing (Stronglight O'light AL 1 1/8") only to find head tube and fork tube have thick layer of pinkish sand all over. Some has descended into the lower bearing and knackered it.
But how could it have got there? There are only two small holes where head tube meets frame tubes. Otherwise completely closed. Couldn't have found it's way in past the bearings.
It looks to me like this could only have been there from the beginning. Sand blasting or casting sand perhaps?
Anybody experienced this?

NB I haven't cycled anywhere near a source of fine pink sand! This is a road bike - a few miles on good trails is as rough as I go.

PS I now recall that the same sand was in the bottom bracket shell when I serviced it a year ago.

[hamster]

Sounds like blasting residue...unless you bought it in Libya...

[gerrymcm]

This happened to me with a second hand frame, which had been freshly powder coated. Fortunately it was bead blasted so was easy to hear so I had a chance to clean it out before us.