Wetplate intensification, a very important step to make the correct negative for printing out processes.
Wetplate intensification is a necessary step for to condition negatives to the correct density and contrast to be suitable for alternative processes printing, such as salt paper, cyanotype, Van Dyke brown, kallitype, platinum-palladium, and so on.
Intensification process is also called redevelopment. The two terms are expressing the same value. Intensification is more precise, while redevelopment usually describes the second part of a split-process. Where you will read the term ‘redevelopment’ please consider it stands for ‘intensification’.
Wetplate intensification was absolutely a necessary step in between the shot and the varnishing phase at the time of wet plate collodion.
During the era of wet plate collodion photography, wet plate intensification process was necessary to get the correct grade of contrast on the negative. The constrast control was only possible via making a correct negative. At the time the printing materials were not ‘multicontrast’. Contrast had to be set before to get to the print phase.
Intensification was taken in great account also later on, with dry plate and silver gelatine film photography. I think intensification was slowly abandoned when graded photo papers appeared on the market. The way the contrast could have been modified later at time of printing, just choosing a harder or softer grade of paper, made it obsolete.
The Internet is full of intensification process procedures, but when it comes to wet plate – I don’t know why – only a couple of procedures arise.
My wet plate negatives
The negatives I make with wetplate collodion have gathered attention because they look very intense, harsh and pretty suitable for the alternative photographic processes with printing out papers.
Indeed they are. I like to shoot wet plate collodion for to make tintypes, but I like ambrotypes even more and the print the most. Film intensifications is a process I do since the late 80s and now I’m happy to have a great knowledge and experience on these processes because I can use them successfully on wet plate photography.
Photography must be printed (IMO)
The look of a tintype is very pleasant to me. Ambrotypes are magic to me, especially when mounted unpainted, against a a black canvas. The way they change when pulled in and out it’s fantastic.
But I like the print over all. In the last years I have committed my production almost exclusively to printing out processes. I’m working with salted paper, cyanotype, Van Dyke brown, carbon and kallitype.
Negatives for silver and iron printing must be dense and contrasty, otherwise they print out a very faint, flat, dull image. The only way to get the right contrast and density for a specific process is to redevelop them before to finish the wet plate process.
Density and contrast
[ Note for beginners: if you don’t have a clear idea about contrast and density I suggest to study that matter in depth. There resides the knowledge for to become masters of our art.
In my past I stumbled on some books that became my foundation. Those are Ansel Adam’s ‘The Negative’ and ‘The Print’. You like it or not, the study of the zone system is basic to understanding how to control the negative for the print. ]
For the more advanced photographers: pay attention at the difference in between the two terms wherever I use them. Redevelopment processes act in different ways and the two results are not a consequence one of the other. They must be seized.
Different kinds of wetplate intensification processes
If you figure out the various number of different formulas for the collodion, think that a larger number of intensification formulas were available for the photographer already at the end of 1800s. They can be used on any negative, including the silver gelatine film. The processes are very helpful for any king od analogue photography.
There are basically three kinds of wetplate intensification processes, that can be filed for their chemical action:
1. rehalogenation and redevelopment
2. bleach and redevelopment
3. physical redevelopment
The three basic methods yield to three different results. So, I’m going to briefly explain what they are better suitable for.
Rehalogenation and redevelopment process
That’s one of the most common processes amongst collodionist photographers. There are tens of different processes and formulas, involving diverse compounds. One of the most well known is the process with iodine and pyrogallol.
Wetplate intensification with iodine and pyrogallol
You might have stumbled on this process before of may be you are one of the users. Maybe you know already know this procedure. It’s consisting on a two-steps process where the first one is called rehalogenation and it consists in pouring an iodine alcoholic/aqueous solution on the plate. It should be kept on it until iodine has been transferred to the silver oxide layer.
The process can be done again and again until the desired amount of iodine has been released to the plate. The effect can be easily determined because the solution turns from a red color to a pale yellow one. The second phase is a true redevelopment using a pyrogallol developer. The latter turns the image in a dark silver oxide compound.
Understanding iodine action
The chemical action of iodine is to react with the silver oxide on the glass. The less the silver oxide, the less the iodine will stick on it. The thicker the silver oxide layer, the larger the amount of iodine is deposited on the existing image. At the end of the rehalogenation phase, the very subtle shadow areas have taken much less iodine than the darkest high lights. When the pyro is poured, it develops less the shadows than the high lights, hence creating a harder grade of contrast on the plate. Sometimes the very subtle textures of the shadows seem untouched by rehalogenation and redevelopment.
Wetplate intensification with iodine and pyrogallol is a good process, never mind, but that was intended for to control the contrast for a specific use. If you have ever redeveloped a negative that way you know the process is quite slow and allows the negative to undergo to rehalogenation more than one time. The more the iodine is allowed to deposit, the harder the contrast grade is obtained.
This process was intended for to increase the grade of contrast of a negative of a due amount and snatched before it could go too hard. For to obtain a very hard grade the process must be held for a quite long time.
Rehalogenation with iodine may be good for cyanotype printing, but it’s not for salt paper, nor for Van Dyke and similar.
Bleach and redevelopment process
Depending on the compounds used, bleach and redevelopment can increase contrast AND density at the same time. That means this process not only can give a harder grade of contrast because it does extend the full tonal scale of the original negative, but also can deposit so much silver oxide on the whole plate to overall lift the density from the shadows to the highlights in a very distinctive manner.
Lots of diverse formulas can be found both online and on the photographic literature of the last century. Notable text books are the Italians ‘Foto Ricettario’ by Oscar Ghedina and the older ‘Prontuario fotografico di ricette e tabelle’ by Rodolfo Namias, the last one edited by ‘Progresso Fotografico’ the magazine founded by Namias, being sort of a bible for the darkroom photographer.
The process I use for my negatives is based on copper bleach and silver nitrate redevelopment.
This process is not suitable for small format negatives because it makes the grain of the film coarser. This process is very violent.
With copper bleach I can obtain negatives of a very hard grade which is the core of a good salt and Van Dyke print. Sometimes the negatives made this way are too hard for cyanotype printing. The final results are up to your personal taste.
I believe the contrast is all to a monochromatic print. Such a hard negative allow the exposure in the ‘bromographer’ (UV printer) to be so long that the shadows have plenty of time to expose until they become the darkest possible. All the ferric compounds deposited on the paper will be exposed to death through the transparent areas of the negative. The final result is a print with a very long tonal scale, starting from the deepest cyan hue obtainable from that specific paper.
Copper bleach formula
The formula I use is consisting of three aqueous solutions to be kept aside until use. The first two are the bleach:
- part A: KBr 15%
- part B: CuSO4 30%
They must be mixed at time of use because they don’t last. The third solution is a simple silver nitrate solution. As a matter of easiness I keep a bottle of 6% AgNO3 solution just for this process. Any other AgNO3 solution of any strength will work the same.
The plate is first bleached with a measured amount of bleach for to save solution. A quick rinse under the tap and then the AgNO3 solution is poured on. Don’t rinse too long. The process must be done in controlled light. Avoid UV radiation. I operate in my ‘yellow room’ when handling UV sensitive materials. The entire process is very fast.
This process is mostly dedicated to increasing density rather than contrast. The so called physical redevelopment consists in a bath of silver nitrate mixed with some developer. It can be Metol, hydroquinone, pyrogallol, pyrocatechin, etc…
The process happens in open light. The silver nitrate reacts with whatever it finds ‘at hand’ in the nearby. In the specific case the silver oxide on the plate. So it deposits extra silver on the original silver oxide. The developer mixed together it turns it black while on the go.
Physical redevelopment is quite slow and must be taken under strict control because it does accelerate while going on and thus turning the whole plate black.
Since this is the most gentle process out of all, it does not grow the grain of silver. It is a very useful way of augmenting density on small format films that came out quite transparent and need more body for the print. You can save a bad negative with this process, but it’s not enough for iron salt printing.
Find your own approach to the correct negative
Now you can choose a wetplate intensification process that better suites your needs for your cyanotype boost process. The rule is not fixed on stone. Every photographer operates in different environments, with different materials and personal approaches to the same technique.
So it’s important to tune a process for a personal use. It’s difficult to say what is the best redevelopment process for a photographer, so it’s important to test papers and materials with different types of negatives.
Experience helps, of course. I can say if a wet plate is good or not for to turn it to a negative and in which way I might like to redevelop it. So experience is important to assess my work and save my time.
I suggest the buddy wet plate photographers to make tests and keep shooting. This art is something that teaches to us over time. So my suggestion is take your time to shoot and to test as more as you can. Don’t give up at the very fisrt trials. The perfect redeveloped negative is around the corner, just waiting for you to reach it.
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Happy redevelopments to you all!