This huge machine at Binns road was known as the bonderising machine. Meccano did not use any primer on the Dinky but the debured castings were treated with a phosphate solution then rinsed and dried in this machine, a sort of pre historic dishwasher. The object of the treatment was to roughen the surface of the casting so that the enamel would stic better to the bare metal. This is the reason why your polished models look so much better after your polishing.
