Filtering chemicals...

Hi,

So I have this Ilford Fixer concentration for a long time which is very good, but I guess because of the age it has acumulated some small white dust in it.

I filtered once a mix with coffee paper dilter but I think because of the quality of the dilter it added some more dust which made my photos a bit fogy.

A I wonder if there is an other method to filter my fixer mix in order to remove the dust in it.

Has anyone any sugestion?

With any filter you should re-filter the very first liquid though it, or rinse water through it and discard the water before filtering the solution that avoids dust particles.

However it shouldn't make any difference to your films, I use coffee filters all the time as they are easy to find, I have better lab filter papers but they are slow and less convenient.

Dust won't make your film or prints go foggy.

Ian

marciofs said:

Hi,

So I have this Ilford Fixer concentration for a long time which is very good, but I guess because of the age it has acumulated some small white dust in it.

I filtered once a mix with coffee paper dilter but I think because of the quality of the dilter it added some more dust which made my photos a bit fogy.

A I wonder if there is an other method to filter my fixer mix in order to remove the dust in it.

Has anyone any sugestion?

Click to expand...

Filtering is quite normal, and is applied in replenished b&w and colour systems such as machine processors.

Coffee filters are good, but I find they sometimes can tear.

What I do like is an especially large funnel with an inch wide hole at the beginning of the hole in the funnel that tapers down, I bunch up paper towels in there tightly, works quite well.

Just to add to the information. After mix the solution (filtering or not) the fixer liquid is not crystalline/transparent but kind of white or fog.

The last film I developed the images wasn't fog but I didn't filtered it. This is why I believe the filter had something which added in the in the fixer.

Meybe I try again with an other filter brand.

I'd get some fresh fixer, it sounds like it;s decomposing.

Ian

Ian Grant said:

I'd get some fresh fixer, it sounds like it;s decomposing.

Ian

Click to expand...

+1

When in doubt, throw it out.

Your fixer concentrate is starting to sulfurize. That is it is decomposing and precipitating free sulfur. Once a fixer starts to do this the process continues and cannot be stopped. You can filter but the problem will just re-occur. Toss it and buy some fresh.

So I have this Ilford Fixer concentration for a long time

Click to expand...

This says it all. All acid solutions of thiosulfate are unstable and this is the final outcome of the decomposition process. You can slow the process by keeping fixer in a cool but not sold place.

I have never found coffee filters to be particularly useful. They are designed to work for filtering out VERY coarse particles and do not work well with photographic solutions. Some brands are better than others for our purpose. They work better if you use two filters instead of one. Before the invention of coffee makers people used a cotton ball at the bottom of the funnel. Both filtering methods work about as well. Gently seat the cotton ball but do not squash it down before starting.

Should any sulfur particles stick to the wet film emulsion then you are SOL as they are impossible to remove without damage to the film. Aother rreason to toss this fixer.

As mentioned, it sounds as though your fixer is pretty much finished. Best plan is to make up a new batch.

I use several developers made up from powder kits and always filter them before use by using a ball of cotton wool in a plastic funnel. It doesn't need to be a huge ball and let half a funnel of clean water run through to get rid of any loose material before filtering the chemical. I think there has never been a time when my (clean looking) solutions have not left something behind in the cotton wool.

When I was a child, I went to the local pharmacist to get some filter-papers for filtering the chemicals I used then, and he suggested the cotton-wool + funnel idea as a more convenient alternative. I've been using this method ever since, for more than forty years.

It explain everything.
Thank you all for the help.

By the way. Do you notice any difference among fixer brands, apart from the difference on fixing time??

Thanks..

In the lab when a solution needs to be filtered a filter funnel is used. This style of funnel has a very long stem of constant diameter bore. The idea being that the small vacuum caused by the column of liquid in the stem increases the rate of filtration. Ordinary style funnels can be very slow and tedious for filtration.

Gerald C Koch said:

In the lab when a solution needs to be filtered a filter funnel is used. This style of funnel has a very long stem of constant diameter bore. The idea being that the small vacuum caused by the column of liquid in the stem increases the rate of filtration. Ordinary style funnels can be very slow and tedious for filtration.

Click to expand...

Interesting... I will follow your advice.