View Single Post
  #13  
Old 15th May 2020, 03:00 PM
Martin Aislabie's Avatar
Martin Aislabie Martin Aislabie is offline
Friend
 
Join Date: Nov 2008
Location: Stratford-upon-Avon, England
Posts: 2,081
Default

Quote:
Originally Posted by Michael View Post
From the Hypam data sheet: "Full, unopened bottles of HYPAM concentrate stored in cool conditions, 5–20ºC (41–68ºF), will keep for two years. Once opened use completely within six months and keep all bottles tightly sealed until used".

Apart from issues of supplier's length of storage or temperature stored, I'd find 5 litres of concentrate hard to get through in six months.
Michael, most users decant large quantities of all of our chemicals in to smaller bottles (typically 500 or 1000cc sizes), so that if you were to need 300ccs for example, you would only expose the remaining 200 ccs of your chemicals to considered partly opened.

It is always a good practice to date when you originally decanted any chemicals.

You can then go further to reduce the oxygenation of the remaining chemical by filling the rest of the container with an inert gas such as Protectan (available from Silverprint, AG and others good photographic retailers and FADU sponsors)

Because fixer does not discolour as it ages, you need to check the effectiveness of your fixer from time to time - particularly as you exceed the manufacturers recommended life of the chemical.

Simple Fixer effectiveness test

1) Mix up a working solution of your fixer.
2) Take a 75 mm (3 inch) strip of your typical 35 mm film.
3) Dip 25 mm (1 inch) of the film strip in to the fixer solution and leave it there for 3+ minutes.
4) Insert a further 25mm of the film strip in to the fixer and start a stop watch
5) Watch and wait for the second 25mm portion to achieve the same level of film clarity as the first 25 mm portion. Record the time taken.
6) Your film fixing time should be twice the time it took for the fixer to clear the second 25 mm of film.
7) Do not exceed the manufacturers stated fixing capacity.
8) Typically, fixer is considered to be to old to be worth bothering with if the clearing time for fresh fixer is now significantly greater (increase of 50% ?) than needed to achieve (5) when the fixer was both new and fresh.

Many of us don’t use the full quoted fixing capacity of our fixer when it is older than the manufactures recommended shelf life.

Also remember that any photographic chemical can be store for much longer if it is neat (undiluted) – typically measured in months, than when it is in a working solution– typically measured in days.

Hope this helps.

Martin
Reply With Quote