7. Mix a fresh bath, which now becomes the second bath.

7. Repeat this cycle four or five times before discarding both baths and beginning fresh once again. 

When working it is wise to check fixer baths regularly, not once a day.

TESTING FINISHED PRINTS FOR RESIDUAL SILVER : Since the quantity of silver compounds needed to cause an over all yellow stain on a print or neg is extremely small, there is no simple quantitative method available. However, the sort of stain that might be visible after a period of keeping can be simulated by using the following drop test. Place a drop of Kodak residual Silver Test Solution ST 1 on an unexposed pat of the material and blot off with clean white blotting paper.

Any yellowing of the test spot other than a barely visible cream tint, indicates the presence of silver. If the test is positive, residual silver can be removed by refixing and washing. This test should be carried out before toning because the residual silver has been toned together with the image. The yellow stain so formed is permanent.

KODAK RESIDUAL SILVER TEST SOLUTION ST1

Water..................................125ml

Sodium Sulfide.........................2grams

For use One part stock solution with 9 parts water. This working solution has a limited storage life and should be replaced once a week.

Store stock solution in a stoppered bottle for not more than 3 months. 

Kodak Rapid Selenium Toner can also be used when diluted 1 to 9. Using this solution, follow the directions above. 

NOTE: This test fails where a large excess of Hypo is present, as in stabilised prints.

WASHING : Even small amounts of Hypo (sodium thiosulfate or ammonium thiosulfate) remaining in a photographic material after the final wash eventually combine with the silver of the image to form silver sulfide. The result of this reaction in black and white negatives or prints is a stained and faded picture. For most purposes adequate washing is achieved in an hour in a print washer that change the water completely every hour like those made by Gravity Works. However, the wash time and rate of flow are meaningless if the prints are not separated constantly so that water can reach every part of every print during the wash.

HYPO CLEARING AGENT : In terms of washing it is interesting to note that seawater removes hypo from photographic material more quickly than fresh water. Investigations into this effect have shown that certain inorganic salts behave like the seawater. Unlike seawater, however they are harmless to the silver image. Kodak Hypo Clearing agent is a preparation of such substances. Its use reduces the washing time for both prints and negatives. When used, it guarantees prints are free from residual chemicals that is almost impossible to when only washing in water. It also has the advantage that prints can be washed in much colder water.

Two Bath Fixer method: Below is a two bath fixer method of processing Fibre based prints for permanence.

Some photographers prefer an extended development of up to 3-4 mins to bring out the fine tones in the high lights and I would suggest experimenting with this specifically to the work being printed.

HYPO ELIMINATOR : It is difficult, if not impossible, to remove the last traces of processing chemicals from photographic papers by ordinary means and for this reason photographers have often used a Hypo Eliminator. However it has since been found that while this acts in a beneficial manner it also has some side effects and is now not recommended.