Indicating Stop Bath for Film&Paper
Silberra STOP bath is designed to stop developing process instantly. Using stop bath enlarges fixer's capacity by up to 50% and allows to instantly abort any developing processes in film or photo paper emulsion to comply with exact development time for perfect results. Silberra STOP bath contains chemical indicator which changes color and opacity of working solution when it becomes exhausted.
Chemical Composition
Сitric acid, dibromomalonate, distilled water
Preparing Working Solution (Mixing Instructions)
Working solution is prepared by diluting the concentrate in distilled water while actively stirring.
To prepare stop bath working solution for film:
Dilute the concentrate of Silberra STOP bath to a ratio of 1+49 (i.e. 10 ml of concentrate to 490ml of water to obtain 500 ml of working solution or 20 ml of concentrate and 980 ml of water to get 1 litre of working solution).
To prepare stop bath working solution for photo papers:
Dilute the concentrate of Silberra STOP bath to a ratio of 1+99 (i.e. 10 ml of concentrate to 990ml of water to obtain 1 litre of working solution).
Using distilled water is strongly recommended to ensure best chemical capacity of all the processing chemicals.
Usage
Stop bath is used in processing negative materials between development and fixing stages. To use stop bath when processing b&w film no additional equipment needed. SIlberra STOP bath working solution shall be poured into the tank right after the development time is over and developer is drained. The volume of the working solution is the same as the volume of the developer. That volume is usually written on the bottom of the developing tank.
When using stop bath in photo paper processing one extra tray is necessary for stop bath working solution. The most convenient way to place it is to install it between developing and fixing solution. Prints shall be placed into the stop bath tray right after development; moving the print between developing solution and stop bath and between stop bath and fixing solution demands separate tweezers for each movement process in order to avoid coloring stains on photo paper. When moving the print between trays manually, don't forget to wash your gloves' fingers under the running water thoroughly each time after you take the print.
Effective processing time for Silberra STOP bath is 2 minutes at 18C - 24C temperature both for film and photo paper. Working solution of Silberra STOP bath is reusable and chemical indicating component reveals the exhausted solution by colouring it into shades of blue (while normally active solution is yellow or reddish-yellow).
Storage
Keep Silberra STOP bath in a cool, dry and dark place. Keep away from children. All the solutions should be stored in tightly sealed bottles, with low internal air volume.
Expiry Date/ Shelf life
Silberra STOP bath may be stored in its original sealed bottle for up to 24 months; after opening the bottle, the STOP will remain useable for no more than 18 months. Silberra STOP bath working solution (including partially used solution) has approximately 4 months of guaranteed shelf life after the date of preparation and may be used longer in case the colour of the solution remains yellow.
Usage Limits
1 Litre of Silberra STOP bath working solution is enough to process at least 25 b&w photo film rolls or 0,1 Sq.m. of photo paper.
Disposal Regulations
Silberra auxiliary solutions must be disposed of in accordance with the rules and regulations of the country they are used in. Concentrated photographic solutions of any kind 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.