W. & C. Platinotype.
Development should be conducted in a feeble white light, similar to that used when cutting up the paper, or by gas light.
It may take place immediately after the print is exposed, or at the end of the day’s printing.
Develop by floating the print, exposed side downwards, on the developing solution.
Development may take 30 seconds or more.
During the hot summer days it is not advisable to unduly delay the development of exposed prints. If possible develop within 1 hour after printing.
Either porcelain or agate—preferably porcelain—dishes are necessary to hold the developing solution.
To clear the developed prints: These must be washed in a series of baths (not less than three) of a weak solution of muriatic acid C. P. This solution is made by mixing 1 part of acid in 60 parts of water.
As soon as the print has been removed from the developing dish it must be immersed face downwards in the first bath of this acid, contained in a porcelain dish, in which it should remain about 5 minutes; meanwhile other prints follow until all are developed. The prints must then be removed to a second acid bath for about 10 minutes; afterwards to the third bath for about 15 minutes. While the prints remain in these acid baths they should be moved so that the solution has free access to their surfaces, but care should be taken not to abrade them by undue friction.
Pure muriatic acid must be used.