• Welcome to Photrio!
    Registration is fast and free. Join today to unlock search, see fewer ads, and access all forum features.
    Click here to sign up

Water spots with and without deionised water?

I’m curious about the OP’s water quality out of the tap and whether filtration wouldn’t help here. My darkroom sink has an inline filter installed with carbon block that filters the water down to 5 microns. I don’t use distilled water or hang m roll film at an angle. No issues with spots with the use of photo flo.

In my area my water supply doesn’t have a whole lot in it in terms of mineral content and carbonate. I’d wonder whether a final soak of any reasonable time is just inadequate with, say, very hard water out of the tap?
 
brian steinberger said:
In my experience you cannot use just distilled water for final rinse as you risk differential drying marks.
Click to expand...
That's counterintuitive, given that you'd expect distilled water to be more pure than demineralized or deionized water. Btw, I'd expect the practical difference between all types to be unnoticeable in this application.
 
koraks said:
That's counterintuitive, given that you'd expect distilled water to be more pure than demineralized or deionized water.
Click to expand...

Agreed. Extremely high purity water, whether from distillation or high efficiency deionisation,* contains only a vanishingly small amount of dissolved minerals so should leave no discernable residues whatsoever on the film once dried, regardless of whether a wetting agent is used or not. This is of course assuming that the film was previously washed thoroughly, then with a penultimate distilled/deionised wash/soak (as I already described) to ensure residual minerals within the film itself or the tank are already removed.

*Note that not all "deionised" waters are created equal. Some cheap commercial ones actually still contain non-trivial levels of dissolved minerals.
 
Differential drying - at least as Kodak describes it and possible issues - has to do with different local drying rates (droplets…) potentially causing deformities in the emulsion which can apparently print with different density. In other words, a surfactant/wetting agent is recommended to break the surface tension no matter how pure the water. I don’t know whether or not this is the problem OP has.

Edit: Apologies for editing this after posting.
koraks said:
That's counterintuitive, given that you'd expect distilled water to be more pure than demineralized or deionized water. Btw, I'd expect the practical difference between all types to be unnoticeable in this application.
Click to expand...
 
Last edited:
It's really strange that traces appear after deionized water. Could these spots have formed during development?
The wetting agent is dissolved in deionized water, right? In high concentrations, it can cause stains.
I stopped using a wetting agent - just hanging up the film, shaking it out and gently going over the back with soft paper. This seems to work very well for me.
 
brian steinberger said:
In my experience you cannot use just distilled water for final rinse as you risk differential drying marks. Unless you squeegee.
Click to expand...

What I meant was just using distilled water without a wetting agent and hanging to dry.

I have no experience with deionized water or demineralized water. I’ve never used them.
 

I'm in a very soft water area and can't see deposits on the surface of the film. But I have to say I am borderline conspiracy theorist about UK water atm and better filtration is a good shout generally.

I'm first trying simple drying stage adjustments before looking at water supply again. Another conspiracy I have is that this deionised stuff is just crudely filtered tap water, hence not seeing much difference with or without it. But again, no visible deposits either way.
 
John Louis said:
Another conspiracy I have is that this deionised stuff is just crudely filtered tap water, hence not seeing much difference with or without it. But again, no visible deposits either way.
Click to expand...

Deionized water is very important in a number of processes. If (un)filtered water is used, it can cause very serious damage to a number of facilities and consequently trigger a lawsuit with large fines. The deionization process is not that complicated and expensive - hardly anyone would risk it.
 
John Louis said:
Another conspiracy I have is that this deionised stuff is just crudely filtered tap water
Click to expand...

"Conspiracy" is a generous term for this notion. How about "fantasy".

brian steinberger said:
I have no experience with deionized water or demineralized water. I’ve never used them.
Click to expand...

Really? Distilled water is pretty expensive due to the energy cost.
I suspect that much of the "distilled" water you can purchase is in reality deionized or even demineralized. I don't think labeling is particularly strict, especially in the consumer/hardware store market.
 

Good shout yeah. I think this further supports the differential idea then as most plausible, given same marks are visible with and without deionised and with different Ilfotol dilutions tried.
 
Basically it comes down to your local water supply. I have always lived in areas that the local tap water does not require me to use distilled water.
 
koraks said:
I suspect that much of the "distilled" water you can purchase is in reality deionized or even demineralized. I don't think labeling is particularly strict, especially in the consumer/hardware store market.
Click to expand...

Precisely. Any cheap stuff you buy in the shops should be treated with caution. I bet if you tested them with a good TDS meter you would find them to be all over the place.

Better to distill your own (machines for doing this can be bought relatively inexpensively). I can get ultrapure deionised water from work, but transportation is a hassle.
 

I assumed they were similar. I went through years of trial and error dealing with the same things the OP is dealing with now. When I figured out what worked I don’t mind paying 1.50 a gallon for distilled water to get perfect negatives!
 
brian steinberger said:
I assumed they were similar. I went through years of trial and error dealing with the same things the OP is dealing with now. When I figured out what worked I don’t mind paying 1.50 a gallon for distilled water to get perfect negatives!
Click to expand...

That is really, really cheap for true distilled water.
 
Do not use wetting agent. The last liquid your film should be in, is deionised water. Agitate your film in deionised water for about 30 seconds and hang to dry. No drying marks.
 

I use tap through the process and do a final rinse with distilled. Might want to agitate a bit more at the start to make sure your negative is totally coated.
 
Steam distilled water in my part of the US is $1.29/gallon at the grocery store. I don't know of anybody (though I am sure there is somebody) who is palming off DI water as distilled.

Distilled water is funny stuff. It pours differently - sort of silky - and produces no bubbles as it pours.

It also makes good coffee with the added benefit that your coffee maker doesn't lime-up.

Steam distilled water doesn't use all that much energy. The most brute force method takes ~3kWH/gallon - or about $0.33 electricity / gallon. Industrial regenerative and vacuum methods use much less power than this.
 
Last edited:

This is very similar to what I do, just check when taking the film out of the final photoflo bath that it is evenly coated with no drops, keep it well wetted and hang to dry at an angle. Works for me.
 
cliveh said:
Do not use wetting agent. The last liquid your film should be in, is deionised water. Agitate your film in deionised water for about 30 seconds and hang to dry. No drying marks.
Click to expand...

In my experience this will lead to differential drying marks. Might not happen every roll but it will at some point. Now if you squeegee the water off then you wouldn’t have to worry.
 
I should have attached this to this thread sooner. But here is my original thread from years ago detailing my struggle. Please read all the way to the end because there are a few updated times where I thought I had fixed my problem and I had not.
 
I live in a very hard water area. I use tap water for washing the film, but deionised for the final rinse (with Tetenal Mirasol, of which I have enough to see me out!). Generally I see no water marks, but on the rare occasion they occur, they are always down the centre of the (35mm) film, and on the non-emulsion side, where they are easily removed by rubbing very lightly with a soft cloth dipped in deionised water and blotted dry.
 
brian steinberger said:
In my experience this will lead to differential drying marks. Might not happen every roll but it will at some point. Now if you squeegee the water off then you wouldn’t have to worry.
Click to expand...

Deionised water contains no calcium deposits and can therefore never cause drying marks.
 
cliveh said:
Deionised water contains no calcium deposits and can therefore never cause drying marks.
Click to expand...

I thought the same thing at one time until I learned about differential drying marks. I was in denial for quite a while until I did some research. I’m sure many here could explain better than me. But when a drop of water continues to sit on an area of film and the rest of the film around it dries, the emulsion is “stretched” and causes the area around the drop to form a change in density.

Thus the need for a wetting agent to allow the film to dry evenly.
 
You must log in or register to reply here.
Menu
Log in
Register