Help with Belgian M15 Adrian Helmet

[nzef1940]

Most of these helmets I have seen are in their original brown paint configuration, when did colour configurations change ? WW1 or later? Please see my latest, it appears overpainted. Thanks in advance for any additional information.

 

[2nd.Leibhusar]

A lot of this helmet were painted Black after the war to be used by the Gendarmerie ( police)