Thanks Trevor. The article on unblinkingeye says that 24 - 48 hours is enough to cause the paper to go bad and this has been what I have gotten as experiences by friends. There must be something that goes into making a "better" POP.
One thing is that a POP is made with high silver wrt to salt and this causes fog. Published formulas are unwashed, but Ilford mentions that the Kentmere POP must be washed before coating. So, I wonder......
I assume mine is the old Kentmere POP as I purchased it from Retro Photographic here in the UK.
Well, we certainly have plenty of people on APUG who like to experiment with home-brewing emulsions, so here's an opportunity for them to experiment with the old POP recipes and maybe even improve upon them.
:) It's the next thing up on The Lightfarm ToDo list. Hopefully, our recipe will be joined by many others.
Originally Posted by Chazzy
Has anyone tried soaking regular paper with citric or acetic acid or the sodium salts of these acids?
I understand that POP papers used silver acetate or citrate in addition to silver chloride. The organic acid gives the released bromide something to be stabilized with during the long POP exposures.
Most formulas have Sodium Citrate in them.
POP is not a "classical" silver halide emulsion. It is more akin to albumen than a true grown silver halide and more properly belongs in the early years of photography in the 19th century.
Surprisingly the most recent Patent (that I've read) relating to POP papers dates from 1956. It has to do with stability and improving keeping properties of POP's which is done using a Sodium Metaborate coating to the back of each sheet, which is in contact with the emulsion surface of the next sheet. An extension to this is to use Sodium Metaborate interleaving impregnated sheets of thin paper.
Kentmere use a thin interleaving sheet but whether theirs were impregnated with something I don't know.
It isn't that many years since Ilford stopped making their own POP paper, it wasn't sold to Photographers, instead it was packaged in education packs for schools for children to explre light sensitivity and make photograms etc.
There is still a need for POP's as it's one of the best methods for getting the best prints from many older pyro developed glass plate, although of course you could use digital I suppose :D
hmmmmm thanks for the info all. I wanted to do a series of images but no.
To the person who said salt prints, thanks, but you do realise it is a different look don't you? Albumen is closer.
Not necessarily, check out Frances Scully Osterman's waxed collodion salt prints.
Mark and Frances' waxed salt prints have no collodion. The wet plate collodion glass negative is where the collodion is involved, not on the actual print. But a waxed salt print has a different look than the sheen of an albumen print. Wax can be applied to almost any print from a platinum/palladium to an inkjet and it is as simple as it sounds and that is applying it to the surface. An albumen print on the other hand is albumenized before it is sensitized in silver nitrate which gives it a different look than a salt print that has been waxed.