how can I clean laser tube from braunish layer?

[waltfl]

Hi all
My 40W CO2 tube shows now a braunish collor and the end where the water comes in and where the water goes out
I but nothing seems to clear this out I have only used destilled water and changed it a few times I try vinegar but did not help ether
does somebody knows how to clean this up or does it makes no differenc in laser output?
thanks
walt

[crozza]

Maybe flush it with Bi-Carbonate Soda.....Its good for that type of thing. Also harmless.

[Raman Narayan]

20% muriatic(aka HCL) acid.
Recommended by some manufacturers!
-Raman