Watkins Factor: developing

Time of first appearance as estimator of developing time for that emulsion in that developer.

In re-working information about Deep/Thick vs Thin emulsions… da-net posers made me do it.

Deeper dive into Time-Temperature of photography.

  • Watkins
  • Sheppard and Meyer
  • Clerc, section 400, the influence of temperature
  • Clerc, section 380 & 381, watkins factors, & combined factors

How Does It Work?

Developing is a process of saturating the emulsion; surrounding the exposed material with fresh developer, then moving exhausted developer. This main process is agitation. The key part of the emulsion is the gelatin. Think of the emulsion as having depth, as well as surface. This emulsion, whether film or paper, has to absorb the fresh developer– this takes time. An induction time. How fast the exposed silver begins developing depends upon the strength (developing power) of the developer. It is affected by temperature, emulsion, etc, but the main factor was the developing agent(s) used.

The watkins method is mainly of use with emulsions suited to development by inspection. It is of great use in making lith negatives, or, somewhat, in making lith-prints. Sadly, in a developer containing two developing agents, the temperature coefficient loses significance when temperature varies much from 20 C.

Developing AgentC
Metol1.25
Paraminophenol1.5
Ferrous oxalate1.7
Pyrogallol1.9
Metol-hydorquinone1.9
Hydroquinone2.2 to 2.8
Catechol2.8

Some developing agents change activity with temperature — hydroquinone loses activity at low temperature. (Jacobsen, p.67)

Temperature coefficients vary slightly with emulsions. Concentration of developer has little effect.

The temperature coefficient of a developer is the increase in speed of development for a 10F increase. A TC of 2 means that a developer works twice as quickly at 75F as it does at 65F — typical Coefficients from the mid-century were: 1.8 for MQ developer(D76), for fine-grain developers (D23), and 2.3 for super-fine grain developer.

Note: pyro and amidol do vary by amount of grains per ounce. Bromide alters the pyro factor.

Compensating Timers

Temperature control is better than a compensating timer. Keeping agitation in line, changes of developer is more important to critical processing than is time-temperature duration. Build tray rockers, insulated, water-jacket trays with lids instead.

But, if you are interested search: Tundra. DLG. ProcessMaster.

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Easy Assembly Color

handmade color was once the main way of making a color print. At first, obviously, the first color photograph was made by a technician — not purchased, but made. That process was an assembly process. The print was made by layering separate images until they formed the final single print. This was the synthesis step in a “multi-color” process.

Assembly systems are divided into “roll-up” and “lay-down” methods. Was it a ‘dye’ or a ‘pigment’ that is being assembled. They could also be classified as ‘direct’ or ‘indirect’ transfers. These processes are more mechanical than any other way of making prints. The whole direction of the Kodaks was to do the assembly at manufacture time: the integral, type C process. The key researcher for Dye Transfer was moved from dye transfer to type C print work by 1961.

The two most successful systems, those have large enough commercial backing to sustain many users, were Carbro, and Imbibition printing. Imbibition prints were more often known as Dye Transfer, and Wash-off-Relief.

Either process was time consuming, involving many steps with moderate to high skill needed at each. The difficulty lay in the combining of the steps in such a way as to be able to solve more problems than you created. Each stage offers choices; making the best choice comes from having a nice overview firmly in mind.

Either process could be described as consisting of very few steps. Leave out enough and we could just say: expose then print.

Teaching was always a balance between showing, telling, and knowing what to leave out.

Early Equipment was primitive by what anyone working in this century would have:

The processes compared in “follow list” form make their relative complexity obvious. Obvious about why Carbro was replaced. And why Kodak spend so much effort to follow the imbibition path broken by Technicolor.

The biggest step to take these days is: make tissue, or make matrix film. The history of assembly has returned to the carbon route. Firstly because the alt photography community began it as part of the 60s photography surge.

I’ve posted enough over the past years for someone to be able to make matrix film. There are enough webpages and specialty groups for anyone to be able to make their own carbon tissue. Carbro is a different, but easy enough alteration to carbon printing. Just about any soft emulsion photopaper can be used. Bromoil is harder to make than a carbro.

To begin. Begin. Make your own outline. Start with the minimum, not the maximum. Go faster than you feel you can. Make more mistakes than you want. If you read for an hour, print for three.

Assembly isn’t easy until it is done.

Learning Dye Transfer

Maybe. Actually, not. Kodak Dye Transfer ran its course — it was a commercial darling, but a market failure.

One difficulty with learning the process was in getting the relevant information together. Too often the beginner was stalled with too little information; more often they were showered with too much information. Like most first steps those first choices of: ‘how much is enough’, and ‘where to get it’ stalled most learners. Like this bit of information:

A Table of Contents:

  • Making color separations
  • Separations from masked transparencies
  • Evaluation of separation negatives
  • Post treatment of separations
  • Masking
  • Fake color and other alterations
  • Controls beyond
  • Materials and tools for separations

AND where is it now? You of this post-Kodak world learn from the survivor — the loud survivor. Many of whom are known more today than they were then. They didn’t participate in the labworld, instead they lived on the edge by writing about the process — word by word. Dollar by dollar. Until in this electronic forum they are the only voice. What do they say? Mostly tales of their purchases and notice of their sales — everything is on layaway.

Off site links illustrating the world view of those that did not, as they talked with one newcome who did — She became the spine of OIC, the only group who rolled new prints with a new matrix film (F18).