Yeah, it's very cool, I found a rather interesting document on the chemistry to create a lippmann plate 'The True Colour of Photography' by 'Hans I. Bjelkhagen,

Yeah, it's very cool, I found a rather interesting document on the chemistry to create a lippmann plate 'The True Colour of Photography' by 'Hans I. Bjelkhagen, Darran P.M. Green' seems their exposure times where in the order of minutes.