Find "how Coffee as a developer agent " for silver salts was discovered by the author in 1989 in Costa Rica: Coffee Art History

Coffee contains several reducing agents capable of reducing
exposed silver halide to metallic silver. Among these there are
tannins, sugars, catechols, polyphenols, and the most powerful:  Caffeic Acid, which is a complex form of Cinammic acid. (simple Cinammic acid, however, has no reducing power, but a legion of other organic acids present in coffee, may)

Vitamins in coffee, like Niacin (vitamin B3) Ascorbic Acid (vitamin C) and other strong reducing compounds are partially destroyed or transformed in the process of roasting.

There are many factors influencing the rate of development, the contrast, the amount of coffee stain and the fog level of the coffee developed image. Among these are:

-Acidity
-Type of Coffee
-Type of alkaline activator
-Concentration




ACIDITY 

the great acidity of Coffee requires first to be completely  neutralized and then its ph raised to a strong alkaline level to be active as a developer.

Not all coffees have same acidity. Acidity depends on the soil on which the coffee plant was grown. Even on the  same soil, the coffee crop of one year may vary  in acidity to the previous crop or the one of next year, Therefore this variable will determine the amount of alkali required to activate it. The rule is to add enough alkali every time.

Coffee solutions on standing (like wine) may increase their acidity.  The optimum amount of
alkali is to be determined  by trial and error for the particular type of coffee being used. Once this has been determined, if the type of coffee is not
changed, and neither is the type of alkali used, consistency of results will be generally maintained.

Developing temperature should not be higher than 23c, in fact, against all types of fog and coffee stains: 20c should be even better.

ALKALI

The type of alkali used to activate the coffee has a capital influence on the amount of contrast, coffee stain, speed and fog of the developed emulsion.
caustic soda tends to produces fog and increases the  coffee stain without real gain in  emulsion speed.

Nothing against the mild sodium carbonate, which main  disadvantage is its failure to activate very acid type of coffees.

CAFFEINE 
 
At Present, the processes of separating the caffeine from the coffee beans, involve treating the beans with boiling water, steam or solvents. In all of these processes, some of the reducing agents and vitamins leach out as well. The coffee looses its properties.

Tests on some samples of decaffeinated coffee gave pictures with less contrast than the contrast given by ordinary coffee.

CONCENTRATION 

All conditions being equal, a 2o% ordinary roasted ground coffee solution is more active than a 10% solution. However,
when 2 different types of coffee are compared at the same concentration, for example:

a 10% "instant" type of soluble coffee is usually about 100% more active than a 10% ordinary coffee ( not soluble type) solution.

With the second, exposure may have to be doubled to equal the activity rate of the first.  the soluble coffee is generally less acid and its coffee particles being so much smaller, penetrate the emulsion faster and deeper which at the same time also tend to stain the whites with a stronger yellow coffee stain.

ROASTING

Dark roasted ( at about 200-220c) " espresso " type of ground coffee compared with a medium roasted coffee, ( roasted at 175-190c) show no dramatic differences. They have similar activity.   The dark roasted coffee may result in about 50% cleaner whites, because the finer coffee particles have been burned out,  thus their staining power has been reduced by heat.

Also the great amounts of sulphur molecules present in coffee suffer more changes at 220c than at 180c. Sulphur compounds may increase yellow stains.  The Amount of yellow Tar developed in Coffee by  roasting may increase at higher roasting
temperatures, but play no significant role in staining of the whites.
Dark roasted Coffee in some cases has shown to yield a little more contrast.

COFFEE STAIN

1) Regardless of the type of coffee or alkali being used, To get cleaner whites, Always, right before use, The coffee should be agitated to re suspend the heavier coffee particles that settle at the bottom of the vessel with time, if the coffee is drawn from the surface, without suspending the sediment,  it will  have about the same activity but the whites will be yellower, another words, with a stronger coffee stain.

2) if a 20% solution of ordinary ground coffee, Dark or Medium Roast, (after straining or filtering the coarse coffee grounds) is used,
instead of a 20%  solution of soluble coffee (instant type) the whites will be a lot cleaner.
Soluble coffee acts like a dye, with more staining power than the coarser  normal coffee which acts as a "pigment" with less staining power.

See How
You Can
Make

your own alternative photography emulsion

in link below

Make your own  alternative photography emulsion
and make pictures on anything

make your own 35mm photo negative
film on glass plates

Above: An Extraordinary Sample of Coffee Art.
Silver Print on Hand Made Banana Fiber Paper . Paper was first
painted with a white oil paint, coated with our liquid silver emulsion,
exposed, and Developed With Coffee.

PHOTOS DEVELOPED WITH COFFEE Is One Of Our Custom
Coffee Graphics and Custom Coffee Art Services Found
HERE: 

Custom Coffee Art   

Above: Silver Halide Coffee Art.
Hand Coated, Fiber  ( Textured )
Photographic Paper Developed with Coffee.

Watercolor Paper was made " Photographic " by coating it with our
LUCENTA LIQUID SILVER CHLORIDE PHOTO EMULSION

ABOVE:

Coating your Own Photographic Paper
With Our Liquid Light
Silver Chloride Gelatin Emulsion

Find How To Make Your Own Photographic
Paper With Our Liquid Light Sensitive  Silver
Chloride Gelatin Emulsion,  HERE:

Lucenta Silver Chloride
Liquid Photo Emulsion

Above: Machine Coated Smooth (RC) " Ultra Rapid "
Commercial Photographic Paper Developed With Coffee

Content on this page:
copyright ©2005 - 2007
by Saul Bolaños