Alternative way to check your fix is still fresh.

Here are two simple and easy ways of checking that the fix is not exhausted. The bottom line is if in doubt, throw it out.

1. Take a drop of fix and place it on some blue litmus paper, if it turns red the fix is still active, if the paper remains blue it is exhausted. Rapid acting fixes by their nature will get exhausted more quickly than an ordinary one. When fixing paper you may expect to get thirty to forty 18 x 24 cm ( 8”x 10”) sheets per litre.
2. Take ten ml of fix and add ten drops of potassium iodide solution to the measuring jar and stir. If the milky solution does not clear after it has been shaken then the fix is exhausted and a new batch should be made up. If it clears the fix is OK to use. Make up your Potassium iodide solution from two point five grams of powder and add a thousand ml of water and mix. This method does not apply to rapid fixes.

These methods will work for your film fixes as well. But the milk test you do for film will not work with paper as you cannot see this stage with paper.

A fixing question.

This is the second most important part of the process after development. Proper fixation ensures the longevity of your prints and negatives. Fix works by removing the unused silver bromide particles from the film or paper. If not done properly, over time they turn black ruining the image.

 

The way the fix works on the emulsion is to chemically convert the remaining silver bromide into complex argentothiosulfate an insoluble  and unstable compound which after a few seconds can be seen on the film  as a milkiness (not visible on prints) this should be allowed to continue until it has disappeared otherwise the negatives will turn black. As the process continues the fresh hypo from agitation turns the insoluble into soluble sodium  argentothiosulfate which can be washed away in water. The fixing of the image is quite quick, it is turning the by products into a water soluble compound that takes the time.

The darkroom practitioner needs to be carefully when choosing a fix as some cause staining when being used with paper. There are three types: alkali, plain, and acid.

•         Alkali are the most modern and efficient with today’s emulsions. They are the easiest to wash out of papers and cannot be over fixed.

•          Plain is a mix of Hypo (thiosulfate) and water that should be used as part of a two bath system, then only as a second one as it can cause staining and other problems.

•         Acid fixes are known to be quick and should be timed carefully as they can cause bleaching. Hence the reference rapid.

Some fixes come with hardening and should not be used if you are thinking of toning prints. Otherwise it is down to personal choice.

Film Fixing.

 

A lot of people ask how long will the fix stay fresh and how many rolls it will process. I mix up  1000 ml or 1200 ml  depending on how many rolls of 35mm and or 120 format I think will be processed at the same time. ( I  use a different fix for paper) I keep the fix until I have developed a mix batch of between twelve and fourteen rolls. Which can take some months to achieve.

 

The film has a milky look after one minute in the fix

There is a more scientific way of being sure what the limits of the fix are for yourself. It can only be done with a fresh batch of fix. After the film has been in the fix for a minute you open the process tank, checking to see if the milkiness has cleared. If it has then give the film a further three minutes this will also establish the time the film needs to be fixed for. You will need to do this check  with subsequent films until the clearing time is double what it was when the fix was fresh. Having kept a check on how many films you have processed this will give you a safe number per litre for the future, hence removing the need to check each time. There are other method for checking fix life which will be posted later.

Paper fixing.

There are two methods to choose from.

•         Two bath method. This where two lots of fix are made up and set side by side. The first bath does all the work, with the second bath removing any argentothiosulfate that have not  been converted to sodium argentothiosulfate in the first place, making for a more complete final wash. Once the first bath is exhausted (which you will need to test for), the second bath becomes the first and a new one is mixed for the second. When the second now first bath is exhausted both should be ditched and two fresh fixes made up.

I use this method occasionally If I'm toning. To get round all the testing you need to know how many prints you can get out of the fresh  bath and the partly used second, for each of the sizes you print most often. It is a lot of work to start with.

 

•         Single bath. Is a fast acting concentrated fix that takes one minute to do the job. This method needs to be timed exactly; to leave it longer will negate  its advantages. Most of the fixing is done in the first fifteen seconds, to leave it longer than one minute will allow complex compounds to build up making them difficult to wash out.

 

I use this method most of the time partly because I do not have a lot of time to spend when printing and the other is I do not do a lot of toning.

Please note: when fixing papers you should check what the manufacturer suggests in the instruction provided with the paper. I have noted the recommendations have changed since writing this article.  

Processed print faults

Exhausted Developer

With all the processes that need to go well when producing a print in the darkroom it is surprising that faults are not more common. Even so the odd  one comes along to de-rail a good printing session. It does not matter how experienced you are sods law trips us all up!

Exhausred stop

Here are some of the most common faults: 

●         Chemical fingers - this where odd irregular marks appear on the finished print usually at the edges. Make sure your hands are free from chemical contamination and dry before you handle photographic paper.

●         Exhausted developer - fails to produced a full image once it has reached its completion time.

Exhausted Fix

●         Wrongly diluted developer - produces faint grainy image. A bit like the above.

●         Exhausted stop - leads to a purple tone to the white areas of the print.

●         Exhausted fix - the slow brownish toning of the finished print in day light.

Related Posts:

Fixing negatives and papers

It is important to fix your negatives fully, this will ensure their longevity.

Fixing removes the last of any light-sensitive material from the negatives stabilising and securing the images so they can be viewed in day light. The temperature of the fix should be the same as the developer and stop bath, 20 degrees C.

Most fixers nowadays are rapid fixers supplied in liquid concentrate form and will complete the fixing process in about two to five minutes. (always check the instructions on the bottle) over fixing will start to bleach the negative. These fixers are usually suitable for film and paper. There is a chance in the case of warm tone papers that they may suffer from bleaching of their warmth with rapid fixers, it would therefore be better to use a more traditional fixer made up from a powder to ensure no loss of tone.

Wet side of the darkroom.

On this side of the room you will have laid out your developing dishes in the following order: developer, stop-bath, fix, print washer and/or sink. These may have heaters under them or you can have a slotty laid out in the same way. Obviously this will take up less space.

Typical wet side layout

This is where you keep your chemicals, it is also the place that the solutions are poured out and back into their storage containers. The height of this table needs to be right so you can work comfortably in the standing position. It is a good idea to store these chemicals under the table if there is a leak it will go on the floor and not drip into your working dishes ruining your prints. For safety reasons it is not a good idea to lean over your dishes to retrieve items from shelves above while your working as you may knock the contents of the dishes over yourself.

Remember that these chemicals need to be treated with care and you should follow the safety advice recommended by the manufacturer.