Commercial photographic printing papers, although still available in quite a variety of types and finishes, impose several limitations. The paper type is pre-ordained by the manufacturer and must be a highly machined product that will pass through the elaborate manufacturing process. Probably the greatest constraint is that the printer is limited to working upon a two dimensional plane.
Self-coated emulsion offers the simplest way to unshackle oneself from the manufacturer, as an image can be placed on a wide variety of surfaces, many unusable with other alternative photographic processes. In addition the high speed of print emulsions means that enlarging can be employed, unlike the contact-speed processes. In the 20 years or so since high quality photo emulsions came on the market a new chapter has opened up in the history of the medium, and placement of traditional photo imagery has taken on a different dynamic - shape, dimension, surface quality and type of base material are all in the hands of the print-maker.
In recognition of this we produced a book 'Silver Gelatin' in 1996, which covers the technical aspects of emulsion work exhaustively as well as containing extensive colour portfolios. Now in its 3'rd edition, recommended to everyone wanting to work seriously with emulsion.
A website primarily dealing with emulsion work is 'Light Farm';
There is also much ongoing discussion on emulsion techniques within the Analogue Photography User Group (APUG)