Hypo-alum

It is not necessary to make test strips with toners that are meant to work to completion, such as bleach and redevelop toners (for example, hypo-alum, sepia, etc.), as partial toning will result in an unstable final print. However, it may be desirable to tone a single strip of a correctly exposed and developed print and keep it among the toning swatches. 

There are two types of toner that can be used to completely convert metallic silver. The first are sulfide/hypo alum toners which can be used to completely and uniformly convert the metallic silver to silver sulfide. The second are selenium toners such as Dassonville T-55. 

The sepia/sulfide/hypo alum toners are the most stable as the selenium toners will only protect the shadow areas, not the highlights, unless toning is taken to completion, in which case the entire print will take on a color/tone, which will depend on the paper used. 

However, by using a single-solution, sulfur-reacting toner such as Kodak T-la Hypo-Alum Sepia Toner or Kodak T-8 Polysulfide Toner (Formulas Toners Brown Toners) it is possible to convert the entire print at once. When this is done, the print cannot degenerate any further and instead of a ruined print the result is an archival print. 

With most sulfide/hypo-alum toners the color will be sepia to deep brown depending on the toner, paper, and developer used. However, polysulfide toner at dilutions of 1 100, has been found to protect most papers with little or no color shift. 

Sulfide/hypo-alum toners are reusable and often improve with age. They usually contain a milky-white deposit, the result of sulfurization, which should not be filtered but stirred well before use. 

The following are suggestions for sulfide/hypo-alum toning. 

While chrome alum can be used in hypo-alum toners, it is more hazardous to the environment and so potassium alum is preferred. 

Uses In fixing baths hypo-alum (sulfide) toning hardener for gelatin. 

Uses Hardening solutions for fixing baths ingredient of the hypo-alum toning bath clearing bath. 

Uses In preparation of chloride emulsions salting papers before sensitizing and before toning in hypo alum toning formulas, also acts as a weak restrainer. 

Hypo-alum toner for reddish-brown tones. 

Then add the following solution (including precipitate) slowly to the hypo-alum solution while stirring the latter rapidly ... 

The silver nitrate should be dissolved completely before adding the sodium chloride immediately afterward, add the solution containing the milky white precipitate to the hypo-alum solution. The formation of a black precipitate in no way impairs the toning action of the bath if adequate agitation is used. 

For crimson tones on hypo-alum toned prints. 

A print toned in hot hypo-alum may be further toned to a rich crimson by gold toning. 

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