Hi,

pure solvents may be too benign for removal of such stains, but there are several ways to clean Your glassware usually in this order:

a) Conc. H2SO4

b) Conc. HCl

c) H2SO4/ Sodium dichromate conc. solution

In some cases Acidic/oxidizing agents do not do the trick then:

d) Sat KOH solution in EtOH (do not expose glassware to this longer than few hours, because it may start eating away at it) -> followed by 1M HCl and then water

If You have done all of these steps and the stains still remain then Your reagents have probably reacted with the glass, nevertheless the glassware will be pure, just look stained.

Cheers,

Kaspars

The glassware is etched. Replace it.

Thanks for answers. Mr. Leduskrasts, I am going to use that cleaning methods. Thanks again.