by Christopher Osborne.
Does the world need more Black & White chemistry? Well, perhaps so. Because Tetenal’s new Parvofin developer and Superfix fixer come in tablet form.
Tetenal have announced an exciting new developer and fix combination for Black & White chemistry. Does the world need more Black & White chemistry? Well, perhaps so. Because Tetenal’s new Parvofin developer and Superfix fixer come in tablet form.
The Parvofin developer tablets are a reformulation of a developer which Tetenal has previously manufactured. It has been redesigned, and so for example Borax has been replaced by an alternative compound. These tablets meet the latest safety standards.
The sales datasheet says this developer was sold in the 1950’s although an internet search suggests that a variant of this developer may have been available as early as the 1930’s. It is described as a general purpose developer which balances fine grain against contrast.
How are these products used? The tablets are dissolved in hot water to create a stock solution. A temperature between 50-60 degrees C is recommended and so this is warmer than water from a normal household tap. The tablets dissolve when stirred and the resultant stock solution is then left to cool to 20 degrees for use.
The Parvofin developer is made from 2 tablets, and each retail pack contains 10 of each tablet. The recommended retail price is €29,20 and the whole pack can develop 20 films.
Conveniently Tablet A is larger than Tablet B to avoid confusion. Each set of tablets makes 150ml of stock solution, so for example to make 600ml requires 4 x Tablet A and 4 x Tablet B. Unused Pavofin developer stock solution stored in airtight containers has a shelf life of 1-2 months, and used developer will last for a shorter period.
One might expect the Parvofin tablets to make a 1 shot developer. Instead, Tetenal have taken a more economic approach and instead the tablets are used to make a reusable stock solution. Using our 600ml example the stock solution can develop 6 rolls of 135 or 120 film.
The stock solution can either be used straight or can be diluted 1:1 for use. The developer can be used for traditional films as well as modern films like Ilford Delta and Kodak T-Max. Constant agitation is recommended for the first 30 seconds followed by intermittent agitation every 30 seconds. Times range from 4-8 minutes depending on the film and Tetanal provide recommended times for common films.
The Superfix fixer uses a single tablet. The formulation is a rapid fixer with a shelf life measured in years. Each pack contains 20 tablets which will make 3 litres of film fixer which is capable of fixing 30 regular films, although the capacity reduces to 20 rolls of Ilford Delta or Kodak TMax. Alternatively the tablets can make 4.5 litres of paper fixer. The recommended retail price is €22,85.
Why would one want chemistry in tablet form? Today’s chemistry comes as either liquids or powders. Liquids are heavy and are therefore expensive to transport. Powdered chemistry runs the risk of the user breathing in the chemistry dust, and some institutional users insist on liquids to avoid this risk. Tablets are light, and have a long storage life, and are extremely safe. And they are easy to mix.
We can envisage three groups who this product will appeal to. Institutional users such as schools and universities may be attracted to a safe alternative to liquids. Occasional home film developers may well like the shelf life and the ability to mix just enough stock. And travelling photographers may find these ideal products for hotel room developing to beat X-rays.
Do these products work? Tetenal have dispatched some chemistry to SilvergrainClassics for evaluation. We will let you know as soon as we have tried it.
Images © Tetenal 2021.
Visit Tetenal at https://tetenal.com/en
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