The comments on "cleaning" methyl green are wellvery well made.

One comment to add - it IS possible to purchase pure methyl green.  
Merck sell it and the BSC certify it.  Hans Lyon did find that it was 
not always pure or even methyl green.  What he found on examination 
was that it could sometimes be, or be contaminated by, ethyl green.
Importantly, it made no difference to performance (in MGP 
staining), whether it was methyl or ethyl.

As has been so well described in earlier correspondence, it is the 
oxidation product that causes the problem.

I think it is Barka & Anderson's book - Histochemistry -  that 
describes the use of tertiary n-butanol  for dehydration after 
staining and which helps keep the green staining green, not blue.

See also the latest edition of John Kiernan's most excellent book
ISB 0 7506 3106 6

Russ Allison, Wales