Rapid Fixer milky white?

[andrei_farcasanu1]

Hi all,

 

So I realized that my concentrated Ilford rapid fixer got a milky white color when mixed with water (from a 5L bottle, half full) It has more than the stated 6 month by Ilford sheets. 

I just mixed a 1+9 dilution and run the "negative strip test" and the fixer cleared in below 1 minute. What should I learn from this? It s white because extended shelf time, but still works well?

Thank you so much in advance!

[SCL]

Let it sit after dilution for about 1/2 hr and it will fully dissolve and become clear.

[Alan Marcus]

Test it yourself easy to do this! Cut off a snippet of the film leader protruding (tongue) from a 35mm film cassette. In normal room light, swish this snippet in the working strength fixer solution. The film snippet enters the solution opaque gray. In just a few minutes, it begins to clear and turn transparent. Time this reaction. The correct fix time is twice the time it takes to become clear film.  Work every time as this is a valid test procedure. 

[rodeo_joe1]

Do you have a hard water supply? Minerals dissolved in the mains water may well be reacting with the fixer to form insoluble complexes in suspension, or even minute gas bubbles that turn the liquid milky. If they're solid particulates they may re-dissolve slowly, or settle out as a slight sediment. Gas bubbles will obviously dissipate as well.

I wouldn't worry if the fixer is working properly and doesn't throw white scum onto the film. 

[glen_h]

I have had Ilford rapid fixer silver plate the inside of my bottles.

And, I believe, before reaching the rated capacity.

 

If you have questions about the water, store bought deionized, or even distilled water,

isn't all that expensive. 

[Tony Parsons]

As a matter of interest, would a normal domestic water filter remove sufficient minerals to prevent this happening ? I use mine to filter water before boiling it for tea (this is England, you know !), to prevent the build up of limescale in the kettle.

[glen_h]

There are many kinds of filters for drinking water.

 

In the US, we there are water softeners with ion exchange resins to replace all the

calcium and magnesium ions with sodium ions.  Normally, calcium ions aren't much

of a problem, though.  It might be that iron ions are more of a problem.

[rodeo_joe1]

8 hours ago, Tony Parsons said:

.... would a normal domestic water filter remove sufficient minerals to prevent this happening ?

It depends what sort. The cartridge-in-a-jug type filters are mainly charcoal to remove the chlorination taste/smell, although they might have some ion-exchange resin pellets in there as well. 

A proper in-line ion-exchange purifier is very expensive to fit and run. 

I used to fit my darkroom tap with a reverse-flushable fine particulate filter. Just to stop visible crud from speckling the film. It had no effect on dissolved minerals, but then the water supply in that area was very soft. 

I've since moved to a hard water area, but I don't develop much film these days, so it doesn't bother me too much. 

FWIW, some commercial developer formulations contain sodium hexametaphosphate (Calgon) or a similar sequestering agent. So adding a bit of Calgon to the water used for making up processing chemicals and the final wash water shouldn't hurt. But I'd still use an additional particulate filter to stop random crud settling on the film. Mine consisted of a small cloth 'cartridge' enclosed in a plastic cylinder that fitted straight on the tap via a rubber adapter. I think the make was "Micronyl" IIRC. 

[Tony Parsons]

Thanks for the help - I think I'll just get a gallon of de-ionised and use that.

[glen_h]

2 hours ago, rodeo_joe1 said:

 

(snip)

A proper in-line ion-exchange purifier is very expensive to fit and run. 

(snip)

 

 

Whole house sized ones cost between about $400 and $1000, more for harder water.

If your water is hard enough to cause photographic problems, most people want a

water softener for household use.

 

But I don't know that there are small ones, sized for a darkroom.

 

For actual deionized water, replacement for distilled water, you need both cation

and anion exchange resins, the former recharged with acid, the second with

a hydroxide, and so more expensive than plain salt.  But usually less than

actual distillation.

[Niels - NHSN]

Reverse Osmosis (RO) units can be purchased for very little. The one I use has a modest 75 gallon per day capacity and cost me less than €300 - all filters included.

It is easily installed with average DIY skills. It came with a 1 gallon pressure tank which allows me to pour 1 liter/quart in a few seconds.

With an output of water with undissolved solids of less than 15 PPM (parts per million) it is effectively demineralised water. The tap water where I live is in the 350-450 PPM range!

Beside use for mixing photo chemistry, rinsing film, washing windows, the RO water is also excellent for drinks, coffee, tea and ice-cubes - but if used for consumption you should add a tiny amount of minerals.
That can be a little unfiltered tap water (if your tap water tastes good), or it can be a tiny bit of epsom salt (magnesium), or more easily; by adding a remineralisation filter to the RO unit. 

The latter will raise the PPM to around 40-50 ppm and it will for all practical pourposes still be as good as demineralised water for photo chemistry and rinsing.

This basic RO system consists of a RO membrane that will need replacement every 3-5 years (depending on use) at a €100 cost. The pre-filters will need replacement on a yearly basis and will cost around €30 - a little more if you add a remineralisation filter. It is compact and can be stored under the kitchen sink.

I find this set-up very cost-effective considering I always have easy access to purified water.

[rodeo_joe1]

I just stuck a cheap water-quality meter in my known-to-be-hard tap water. It read 345 ppm after running the tap for a minute or so. However, the last few B&W films I've developed in it have been OK, with no lime scum marks showing up after drying. No strange opalescence to any processing chemicals either. 

If I was developing a lot of film or doing it commercially, then I wouldn't be too happy with that level of dissolved solids.... but I ain't!