From 1910-1920 a german description of developing pop-papers (chlorsilverhalide-gelatinepapers) with developers, but in lower acid pH. This was from the newspaper -Das Bild- from NPG Berlin (NPG was an important photofilm and paper factory in Berlin 1900-1920), page 266 ff: Dr. W. Knopp and Dr. A. Biltz, Erzielung farbiger Töne durch Entwicklung ankopierten Emerapapiers (How to get coloured tone by developing low level copied Emera-Paper). Interesting is on page 267 the statement: the time of copying is only 1/40 up to 1/60 of the time of normal copying and tonfixing, Here is the text - orig. text shortened from unimportance sentences and translated in denglish by Detlef Ludwig, Gigabitfilm. Erzielung farbiger Töne durch Entwickelung ankopierten Emerapapieres Colourtones by developing an underexposed contactpaper Emera Dr. W. Knopp und Dr. A. Biltz ( no date, around 1910-1920) Zeitschrift der NPG Neue Photographische Gesellschaft: -Das Bild-, Heft 9, S. 266-275 Magazin of NPG Neue Photographische Gesellschaft: -Das Bild-, No. 9, page 266-275 1. The copying time need only 1/40 1/50 of the regular copytime. 2. It is in your hand, to to get stronger or lower contrast from the negative; strong exposed copies will develop harder than short exposed copies, which gets softer. 3. Adding low quantities of special additives to the developer, together with normal fixing, results in a enormous variety of colour tones. Yellow, brown, oliv, green, a. s. o. up to carmesinred and violettblack are possible in brilliant, intensive colours, you get in no other procedure. It is possible to get pictures with no goldtoner fixing, you cannot detect from standard goldtoned ones. 4. The durability of such developed papers is much greater than the tone-fixed ones and with the our experience it seems to be infinitively durable. The process of getting a picture is by contact papers not a developing process, it is an enforcement of the exposed grains by the silver richness of the paper itself the physical developing. Normal developers cannot be used for these papers, because all normal developers react to strong and they will fog the paper. Only acid or neutral developers can be used, which work very slowly. In older times all photographer used these procedures. Procedure: You copy until you see the first shadow parts, in normal daylight 2 up to 5 minutes for starting with your experience will suffer. Then lay them by weak daylight in the developer, for a 9x12 cm take 50 ccm developer, because bigger quantities of the developer will solve silverhalide parts of the paper to the solution. The silverhalide of the paper will be to strong divided in the solution and cannot do react as wanted. About durability of the developer we can not say definitively. After some time the developer will get milky and must be disregarded. The surface of the dish get a silverstain, which you must remove from time to time. To reduce this silverstain add as Liesegang told some fishglue or big quantities of gummi arabicum to the developer. Thanks this the backside of the papers stay clean, because without they will get a dark tone. Before developing do not take the paper into water for to minimize spots and holes, because the silverhalide-substances will get out of the paper and you get reduced effects. If it must be, use the same, very little quantity of water for several papers, where you do before one or two not needed pieces of unused papers. When the paper will get good contrast, quickly do out of the developer and follow with good washing for reducing the after-developing. If the developer will contain to much of free acid, a Sulphur-toning will occur in fix-bath. To use NaCl-solution is not recommended, because the tonal quality can be reduced and the whites will get without tonal scales. As soon as the papers will come to the fix, colour will change and they get their final colour after some minutes. After 5 10 minutes fixing is finished, good washing must follow, it is a good device to harden in a 5 % Alaun. Developers 1 -5: 1. Gallus acid 15 gr Natr. acet. 30 gr water 1000 ccm concentr. solution of gummi arabicum 50 ccm 2. Metol 2 gr water 1000 ccm 3. Hydrochinon 2 gr water 1000 ccm 4. Take from Developer 2 20 ccm Developer 3 20 ccm for to get 40ccm 5. Pyrogallol 2 gr water 1000 ccm Developer Aceton Citric acid Silvernitrat Ka-bichroma Cr-alaun Divers colour 50 ccm drops 1: 3,drops 1 : 20,drops 1: 30,drops 1 : 30,ccm drops or ccm 1 - - - - - - brown 1 4 -10 - - - - - green 1 - - - - 5 drops - green 2 - - - - - - phot. brown 2 20 - - - - - goldtone 2 - 10 - - - - brown 2 - - 15 - - Na-sulfit(1:10)10drops karminred 2 - - - - - Wine-acid(1:4)5-10dr. yell.-brown 3 - - - - - - yellow-brown 3 10 - - - - - phot.brown 3 - - - - 3 ccm - reddish 3 - - 5 - - con. Gummi ar. 10ccm goldtone 4 - - 5 - 10 ccm - lightbrown 5 - - - - - - yellowbrown 5 - - - 1 - - greenbrown 5 - 5 drops - 2 - - oliv 5 - 1 ccm - 2 - - chocolate 5 - 1 ccm - 2 - Acetic acid 1 ccm darkredbrown If you want to get colours, then papers will be fix normally in 10 % fixing bath. If you want to tone with gold, then papers will be toned as usual, but you can use only papers with colour-tones in yellow up to yellowbrown as mentioned in the resulting colour list. The other darker tones will not work with goldtoning and if you want absolutely to tone them, then you must do them in follow bath after the fix: A. Water 100 ccm B. Chlorgold 1 gr Rhodanammonium 2 gr Water 100 ccm Soda 1 gr On 100 ccm A add 10 ccm B. Make only as much as you need for the day. In this goldtoner-bath you can change not sufficient pictures in better ones. The most best and cheapest way is to develop papers which have a goldtone-character without any goldbath, simply by developing and fixing. You can get pictures you cannot see any difference from that with gold toned. It is in your hand to get your results, with this list you have an advice how to do it. But there exist much more possible additives and we wish you the best effort. Commentar from 2008: The high quantity of silversalts in pop-paper is used for a combined physical and chemical developing, using low quantities of water. Thanks this a lot of colours (and also neutral tones) are possible, and a good photographic tone is possible with some work, which looks like goldtoned ones. Thanks the reduced exposure a better tonal scale occur, and because the diffusion is lower more details will appear. If the tabelle will appear in disorder because other digital system, you can ask me for the correct one.