Unblinking Eye
Uranium Formulas

 

Caution:  Uranium nitrate is highly toxic--do not allow it to come in contact with skin--wear thick gloves, goggles, a dust mask and a long-sleeved shirt.  Use tongs.

Uranium Toner

 

No. 1

No. 2

Uranyl nitrate 10% sol

25 ml

25 ml

Potassium oxalate 10% sol

25 ml

--

Potassium citrate10% sol

--

25 ml

Pot. Ferricyanide 10% sol

10 ml

10 ml

Ammonium alum 10% sol

50 ml

--

Hydrochloric acid 10% sol

5 ml

50 ml

Water to make

1 liter

1 liter

A normal print may be lightly toned by a brief immersion, but complete toning requires a print of low contrast.  Formula number 1 produces redder tones than number 2.  Tone for 2 to 10 minutes.  Sodium citrate may be substituted for potassium citrate.  The citrate solution may be preserved with a small amount of antiseptic such as phenol.  In order to prevent staining, the print must be washed thoroughly to remove all hypo.  To remove the yellow stain after toning, the following bath should be used several times in succession, as necessary

Potassium citrate

5 grams

Sodium sulphate (not sulphite)

25 grams

Water

1 liter

To ensure permanence, use the following sulphiding bath:

Sodium sulphide

10 grams

Hydrochloric acid

1 ml

Water

1 liter

Or, if the sulphide bath is not used, to remove residual silver from a fully toned print use the following acid fixer.  Follow with a thorough wash in acidified water.

Hypo

50 grams

Sodium acetate

10 grams

Acetic acid 10% solution

10 ml

Water to make

1 liter

Uranium Toner

Distilled Water

500 cc

Glacial Acetic Acid

12.5 cc

Potassium Ferricyanide

0.7 g

Uranium Nitrate

0.7 g

Distilled Water to Make

600 cc

Uranium toning is a modified form of intensification not suitable for dense prints.  Less water may be used to speed the toning action.

Uranium Toner

Sensitizer

Uranium Nitrate

10.5 g

Distilled Water

1 liter

Developer

Potassium Ferricyanide

10.5 g

Glacial Acetic Acid

25 ml

Distilled Water

1 liter

Mix equal parts A and B.  Dilute further if toning action proceeds too rapidly.  Print color varies depending upon the developer used when making the print.  Toning begins immediately.  Just before the desired density is reached, the print should be transferred to a bath of weak acetic acid (4 ml in 300 ml water) for 2 to 3 minutes.  This is followed by a soak in still water until the yellow stain disappears.  Running water will cause blotches.  A 2% solution of citric acid or a 1% solution of oxalic acid are said to give clearer tones than the acetic acid.

Cyanotype/Uranotype

Sensitizer

Green ferric ammonium citrate

7.1 grams

Uranic nitrate

2.3 grams

Water

30 ml

Developer

Potassium ferricyanide

1.4 grams

Water

30 ml

 

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