View Full Version : Distilled vrs. Deionized water for developer

Dan Dozer
20-Apr-2013, 09:01
I always have used distilled water for mixing my developers. However, I now have a Deionized drinking water system in my house and am wondering the difference (if any) between DI water vrs. distilled water for developer. It sure would be nicer filling up from the kitchen sink instead of lugging the 2 1/2 gallon jugs home from the grocery store.

Any of you engineer type people out there who might know?

20-Apr-2013, 09:07
De-ionised is perfect, it's what's used commecially anyway.

I'm assuming you mean mising developers from raw chemicals, if not tap water is OK for commercial concentrates and powdwers.


Pete Watkins
20-Apr-2013, 09:23
I've used both and as far as I can see the only difference is the price. Over here de-ionised is cheaper and that's what I use. Used as a final rinse I never have a streak problem either.

20-Apr-2013, 09:29
I use tap and used to use well. I guarantee you couldn't see any adverse effect

Nathan Potter
20-Apr-2013, 09:39
What Ian says should be fine. When using deionised water there would be some concern about the actual resistivity you get at the fawcett since the quality depends on the type of deionizer beds you are using and the piping system that delivers the water to the fawcett. If you are fussy you would need to measure the water resistivity using a resistivity meter. The upper limit of purity is about 15 megohms per cc. I might guess you may actually be a bit below 1 megohm per cc. with your central system. Untreated water can be as low as 1000 ohms per cc. or even lower if you have an acute dissolved mineral problem.

Distilled water from the store may actually be deionised rather than distilled. My sense would be that store distilled might be, in general, a bit better than a central home deionizing system delivered to the home fawcett since bottled distilled water is prepared and stored under decent controlled conditions.

In my experience a fine water filter is a more useful water treatment aid than a deionizer unless your water is highly alkaline from dissolved lime.

I'm fussy so I use a mixed bed deionizer column followed by a sequenced filter set of 10Ám, 1Ám and 0.22 Ám particle removal for mixing chemistry and final wash for film.
Actually a 1 Ám final filter will easily get you a film clean enough for a 10X enlargement and then some.

Nate Potter, Austin TX.

Dan Dozer
21-Apr-2013, 07:45
Thanks Nate for the info. The unit I have fits under my kitchen sink and has three cartridge units plus an in line filter, so I suspect that it's pretty clean because it isn't a central loop system. Regarding the resitivity - I suspect that it is much closer to 1 Megohm rather than 15. The water here is fairly hard, but the combination of my water softerner unit plus the Deionizer unit get's it really very clean.