Silberra ST-1

Silberra ST-1 Developer is a universal single-solution developer on metol-hydroquinone base. It works as a general-purpose developer and can be used as a standard sensitometric developer for different types of photo materials. The Developer provides good image quality and wide gamma of tones and halftones, doesn't affect final image quality. It is supplied as a set of reagents in two separate packages, designed to prepare 1 litre of working solution.

Chemical Composition

Metol, sodium sulfite anhydrous, hydroquinone, sodium carbonate anhydrous, potassium bromide

Preparing Working Solution

Working solution is prepared by pouring the contents of the packs into water while continuously stirring the solution (use glass stick or special plastic stirring stick for chemicals). Distilled or filtered water is strongly recommended.
The method of preparation is as follows:
1) Warm 750 ml of water up to 35-40 Celcium degrees (use mix of hot and cold water, or use microwave for warming up the water).
2) Pour contents of pack #1 into the water while stirring until the powder is completely dissolved.
3) Pour contents of pack #2 into the water while stirring until the powder is completely dissolved.
Do not begin mixing the contents of pack two until pack one is completely dissolved. If any lumps of powder form in your solution, they can be broken down with your stirring stick. As soon as the working solution is ready (powders are totally dissolved), add cold water to make up to 1 litre and stir.
Allow the solution to cool to room temperature, nominally 20-22 C. At this point the developer is ready to use.
Filtering the solution is not obligatory but recommended option.

Development Times

Average development time of photo paper in newly made Silberra ST-1 Developer at a temperature of 20° will be 1-2 minutes (for resin-coated papers - less than 2 minutes, for fiber-based papers - about 2 minutes).
For films and other negative materials average development time will be about 4 minutes for ISO=100. Optimal time to process specific films is stated either by manufacturer of the film or can be learned from the development times table at this page (the table is being constantly updated).

Usage Limits

Silberra ST-1 Developer for films can be used from 10 to 20 times. 1 litre of the developer can be used to process up to 20 films of 135 type or up to 6 films of 120 type, subject to an increase in processing time of 10% for each film after ther first.
Silberra ST-1 Developer for photo paper can be used to process 0.5 square meter of paper with 1 litre of the developer; such amount of processing will save basic sensitometric properties of the developer. Using the Developer over this limit doesn't guarantee optimal quality and density of the image on the prints and development times should be increased.

Side Effects

Darkening or slight coloring of the working solution will not affect final quality of images while working with negative photo materials. Intensely colored or darkened developer might be exhausted, so we recommend to test it before use and increase the development times.
Please note that Silberra ST-1 Developer increases contrast of the print on FOMA and Slavich photo papers by 0,25 – 0,5 stops due to specific properties of their emulsions.

Storage

Keep ST-1 Developer working solution in a cool, dry and dark place. Keep away from children. It is optimal to store your working solution in opaque, chemically inert and tightly sealed containers with minimal air space in order to reduce oxidation.

Expiry Date / Shelf Life

Silberra ST-1 sealed powder packs can be stored up to 12 months past the production date; ST-1 Developer working solution can be stored up to 30 days, and, if used, no longer than 5 days past the first use. Double concentrate of ST-1 Developer can be stored up to 90 days (in a tightly sealed bottle).

Disposal Regulations

Silberra developers and fixers must be disposed of in accordance with the rules and regulations of the country they are used in. Concentrated developers could be toxic and may harm the environment unless disposed in appropriate manner. Silberra recommends to use special disposal services provided by correspondingly licensed organizations which are eligible for photographic chemistry recycling/disposal.