Causes Of Failures

The images are veiled.

This defect may result from various causes, viz.:

1st. The stock ferric oxalate solution is impaired by a partial reduction

of the ferric salt into ferrous oxalate. The solution should be

preserved in an orange colored vial, and kept in the closet of the

dark room. It should be tested from time to time for the ferrous

salt with a solution of
otassium ferricyanate. If it does not

contain any ferrous oxalate it can be used by adding to it a little

of the iron chlorate solution.

2d. The paper has been exposed to light during the sensitizing or the

subsequent operations. One should bear in mind that the platinum

paper is twice more sensitive than silvered paper.

3d. The sensitized paper has been dried at a temperature above 40 deg.

C. (104. deg. Fahr.)

4th. Over-exposure.

The proofs are not sharp.

1st. The sensitive paper has absorbed moisture.

2d. It is too old. The paper cannot be kept good for over six weeks,

unless special care be taken.

According to Mr. Bory, the sensitive paper altered by keeping is restored

to its original good quality by simply brushing it over with a solution of

0.05 parts of potassium chloride or the same quantity of potassium

chlorate in 100 parts of distilled water, or a mixture of these two

solutions, or one of iron chlorate.

By treating the insolated paper with these solutions, the image is

destroyed, and the paper can be used again. One operates as for

sensitizing, taking care to desiccate the paper, as it has been directed.

The proofs are brilliant during the development, but become dull in


The paper not well sized. It has been dried too slowly.

Remember that it should be quite desiccated within fifteen minutes.

The paper is more or less yellow.

1st. The paper tinted with ultramarine.

2d. The sensitizing solution or the developer are not sufficiently acid.

3d. The washing (fixing) in the solution of hydrochloric acid was not

sufficient to eliminate the iron salts from the paper.

The proofs harsh, devoid of half tones.

1st. The sensitizing solution contains too much iron chlorate.

2d. Exposure too short.

The paper is stained.

The brush not kept clean while sensitizing.

Black spots.

They are generally due to metallic dust in the paste of the paper, or from

particles of undissolved salt in the platinite solution.

NB: No good results can be expected unless the paper be kept absolutely

dry before, during and after exposure, when using the former (original)


Impaired sensitiveness of the paper, want of vigor, tinged whites,

muddiness, indicate dampness.