Steve Machin UK answers a question on why methyl green looks blue as when made
from powder.

A previous answer points out that methyl green decays to form methyl blue and
can be removed by washing with chloroform.
This is done by mixing an aqueous stock methly green solution with a small
amount of chloroform in a separating funnel.  The chloroform removes the methyl
blue.  With several changes of chloroform the chloroform becomes less blue
indicating that there is gradually less of the methyl blue contaminant left. 
Using small amounts of chloroform repeatedly is more cost effective than
washing with larger amounts.
Please read the hazard data and disposal advice on chloroform.  As I understand
it, it may be more hazardous than benzene!  So perhaps a commercial source
would be advisable.

Best Wishes
Steve Machin UK

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