Miscellaneous Photographic Formulas and Information

A working knowledge of photography and chemistry is assumed here, and some of these are in the form of sketchy notes. (For ways of making negatives for blueprints, carbon prints, etc, see the halftones page and high contrast films page for more information.)

back to top of page

Artique's Process

The following is from some scribbled notes. I haven't tried it and don't know the source, but I like the way it sounds like a mess that might work.

2 ways to make sensitizing solution:

method 1 -
dissolve 2 1/2 parts ammonium bichromate
and 5 parts gum arabic
in 15 parts water
neutralize with a few drops of concentrated aqueous ammonia
add 100 parts in volume of egg whites (or possibly gelatine)
and some india ink, enough to make coated paper look black, but still transparent enough to see the shadow of an object placed on back.
beat to a thick froth
let settle 10 or 12 hours


method 2 -
take 10 parts lamp black and
work into a paste by adding 6 to 8 parts gum arabic solution a few drops at a time.
add 1 part liquid glucose in 100 parts water
add 2 1/2 parts ammonium bichromate

filter the sensitizing solution and coat on paper.
expose about 2 minutes in sun
soak in cold water 10 minutes
place on a smooth surface and gently rub with a rag or soft brush to get image up.
then wash in 2 changes of water
and dry.

back to top of page

Notes About the Baume' Scale

n= reading on scale on Baume' hydrometer

A - Liquids heavier than water:
specific gravity = 145 / (145-n) at 60 degrees Fahrenheit
B - Liquids lighter than water:
specific gravity = 140 / (130 + n) at 60 degrees Fahrenheit

back to top of page

Black Lines on White Ground Blueprint

I tried this once and got a very dark purple image on white, which then faded a little and seemed to seep into and affect surrounding papers. I divided the recipe and made a much smaller amount first. It smells terrible and turns your fingers black -- wear rubber gloves. Weird stuff.

10 grams dry gum arabic
328 grams ferric chloride
220 grams tartaric acid
220 grams ferric sulfate (basic)
1000 cc water
Dissolve dry chemicals in order in the water.
In dim light, put two coats of solution on paper.
Let dry in dim light.
Place negative on dry coated paper.
Expose to sun, arc light, or other UV source. Yellow image appears.

develop in:

6 grams gallic acid
and 1 gram oxalic acid
in 1000 cc water


12.5 grams gallic acid
and 12.5 grams alum
in 1000 cc water

develop 3 to 5 minutes,
then wash in several changes of water.
blot and let dry.
(image might spread when wet).

back to top of page

Carbon Process Another scribbled entry I haven't tried, but hope to...

Mix together
110 parts gelatin
25 parts sugar
12 parts dry soap
350 parts water

Add colors:
lamp black, watercolor pigments

Filter mixture
Coat on thin paper (the "tissue" - thin paper that can stand soaking and handling)
Let dry

Sensitizing the tissue:
Float tissue in 2% to 5% solution of potassium bichromate in water.
(less bichromate for less contrast in image)


For exposure with normal negatives:
Use a bath of
30 parts potassium bichromate
2 parts aqueous ammonia
1000 parts water

Have bath at about 60 degrees Fahrenheit

Let the tissue dry in dark room

Put negative on the tissue and expose to sun or other light source

Put the tissue and a sheet of paper coated with alumed gelatin (insoluble) face to face in cold water.
(This gelatin coated paper is the "good" heavier paper, the final support for the image.)
When the tissue softens, remove both sheets of paper, still face to face, from water.
Place on glass and press with a squeegee.
After transfer, let sit 1/2 to 1 hour.
Then place in 80 degree F water, rocking tray until tissue loosens and can be peeled off, leaving the image on the heavy paper.
Then hold the heavier paper, with the image, in an inclined position in 95 degree F water and slosh with water and dash with a wooden spoon to clear image.
(some people pour buckets of sawdust mixed in water from varying heights to clear the image)
If it isn't dissolving and clearing, try 122 degree F water with 5% or 6% table salt in it.
Rinse under tap.
Bathe 2 or 3 times in a solution of 1% chrome alum and water. (common alum can cause reticulation)
Then wash a few minutes and let dry.

back to top of page

Chromium Intensifier

Saves somewhat underexposed negatives.
For drastically underexposed negatives, this will make highlights (if any) heavier.

Stock solutions:

Solution A - 10% solution potassium bichromate

Solution B - 10% solution hydrochloric acid

Working solutions may be mixed in different strengths:
10 parts A 20 parts A 20 parts A
2 parts B 10 parts B 40 parts B
100 parts water 100 parts water 100 parts water

Or, a stock solution may be made of:

3 ounces potassium bichromate to 32 ounces water and
2 ounces hydrochloric acid to 32 ounces water.

Make working solution from 1 part stock and
10 parts water.

Stock solutions will last a long time in full bottles in dark.
Mix only enough working solution to use in one day.

Work in weak daylight or artificial light.
Bleach until all black disappears.
Wash about 5 minutes until yellow stain is gone.
Redevelop in a non-staining developer. (D-76 works. You may want to dilute developer 1:2 or 1:3.)
Fix 5 minutes.
Wash as usual.
Repeat process if necessary.

ps. Sepia toner can be used like an intensifier. When printed, the reddish color of a toned negative makes the negative print as if it was more dense.

back to top of page

Color Temperature (approximate)

light source degrees Kelvin
candle flame 1500
60 watt bulb 2800
100 watt bulb 2850
tungsten type "A" photoflood 3200
tungsten type "B" photoflood 3400
clear flashbulbs 3800
late afternoon sunlight 4300
sunlight at noon 6000-6500
overcast sky 6700-7000
open shade 8000
clear blue northerly skylight 15000-30000

back to top of page

Conversion Chart for Weights and Volumes


gram = g
fluid ounce = fl oz
milliliter = ml
ounce = oz
teaspoon = tsp
tablespoon = tbsp

Volume Weight
1 ml = 0.0338 fl oz
1 tsp = 5 ml
1 tbsp = 15 ml
3 tsp = 1 tbsp
1 fl oz = 29.58 ml
1 cup = 0.2366 liter
1 pint= 0.4732 liter
1 liter = 1000 ml
1 liter = 1.0567 quarts
1 g = 0.03527 oz
1 oz = 28.3495 g
1 pound = 453.6 g

Approximate Weight to Volume Ratios of a Few Chemicals
(how many grams in tablespoons or teaspoons of dry chemicals)
(in grams)
1 tbsp 1/2 tbsp 1 tsp 1/2 tsp 1/4 tsp 1/8 tsp
ferric ammonium citrate 12.5 g 6.2 4.1 2.0 1.0 0.50
potassium dichromate 22.0 g 11.5 7.9 4.1 2.2 1.1
potassium ferricyanide 15.5 g 8.0 5.5 2.8 1.5 0.8
silver nitrate 41.0 g 20.7 13.8 7.0 3.6 1.8
sodium thiosulfate 18.0 g 9.0 6.0 3.0 1.5 0.75
tartaric acid 12.6 g 6.3 4.2 2.1 1.1 0.5

back to top of page

Farmers Reducer


250 ml hypo (sodium thiosulfate), 10% solution
250 ml potassium ferricyanide, 1% solution
water to make 100 ml


make separate stock solutions of hypo and potassium ferricyanide and
then mix equal parts in small amounts for a working solution.

Treat one wet negative at a time in a non-metal tray in room light, agitating continuously.
Remove and rinse in running water before reduction is complete; it continues somewhat even in the rinse.
If reduction isn't complete after several minutes, place negative in fresh reduction bath.
Rinse for 1 minute.
Fix (with hardener) 5 minutes.
Wash 20 minutes.

Small areas may be retouched with diluted reducer (about 1 part solution to 10 parts water) and a small brush, and then rinsed, fixed, washed as above.

Working solution will last several hours.
Dilute working solution with water to slow the action.
If the hypo is increased, it works on the whole scale of tones.
Increasing the potassium ferricyanide will concentrate the reducing action on the middle tones.

Continue to Page 2

back to top of page
return to oatmeal box cameras and alternative photography page
back to centipede the Wendy Mukluk home page
last update September 17, 2000
email me