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.

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(For ways of making negatives for blueprints, carbon prints, etc, see the halftones page and high contrast films page for more information.)

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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

OR

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.

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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

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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

OR

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).

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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)

OR

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

Develop:
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.

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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.)
Rinse.
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.

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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

Conversion Chart for Weights and Volumes

Abbreviations

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)

Chemical (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

Farmers Reducer

Mix:

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

OR,

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.
Dry.

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.

Notes:
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.

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last update September 17, 2000
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