develop with tab water or distilled difference

[Kirk Keyes]

David - Welcome!

We need more people with science backgrounds here.

 

[Willie Jan]

Thanks David.

Did you see a difference using the normal and pure water?

 

[clayne]

You know what I'd like to see scientifically proven or debunked? If particulate matter is capable of being "embedded" into the emulsion during the development process (any part of it). Has always seemed somewhat sketchy to me - even though I have plenty of negs where it sure looks that way!

 

[Ian Grant]

What I am pretty sure will not work is boiling water to remove calcium or other minerals. These are not volatile and will just get more concentrated as you boil off water. It is possible that this would cause some minerals to precipitate so that they would settle or could be removed by filtering. Boiling will reduce chlorine or oxygen. Removing oxygen will help the stability of the stock solution.

David

Some formulae specifically call for boiled water, this is mainly to remove dissolve gases such as oxygen and chlorine and can still be important even if distilled/de-ionised water is used. One side effect in areas of hard water is the removal of a significant amount of the calcium. Where I live in Turkey the tap water is undrinkable because of the high mineral content, boiling produces a calcium scum, which can then easily be filtered out. When I'm in the UK I get the same, as again the water is very hard.

But as I said earlier in the thread commercial developers are compounded to work with all but the very worst of tap waters.

Ian

 

[dancqu]

You know what I'd like to see scientifically proven or debunked?
If particulate matter is capable of being "embedded" into the
emulsion during the development process (any part of it).

Particulate? I couldn't say. What I've mentioned in my post
22 this thread suggests the possibility of emulsion embedding
of silver thiosulfate complexes. Dan

 

[Ian Grant]

The semi-soluble and insoluble silver-thiosulphate intermediary complexes are caused by high silver levels in the fixer and incomplete fiing and not the quality of the water used, use of an HCA can help but only with tipping the equilibrium balance, it won't remove the insoluble complexes.

Clayne's point is relevant because calcium salts etc will form in some cases and cause drying marks on the non emulsion side and embedded particles on the emulsion.

Ian

 

[Kirk Keyes]

You know what I'd like to see scientifically proven or debunked? If particulate matter is capable of being "embedded" into the emulsion during the development process (any part of it). Has always seemed somewhat sketchy to me - even though I have plenty of negs where it sure looks that way!

PE and I were just discussing this situation a couple weeks ago and he talked about particulate down as small as 10 um (microns) as causing issues. The more enlargement used in printing, the greater the problem.

 

[Ian Grant]

And filtering your water will still not solve the problem with hard water as many of the particles form during drying.

I have to admit this is actually causing me a problem here in Turkey, I processed negs for 6 or 7 months before returning to the UK to print, luckily my retouching skills are good but I shouldn't need them The only option is using filtered de-ionised water. Even the bottled drinking water isn't perfect and still has some mineral content. I should add this time of year the water comes from a bore-hole, we are within100 yds/metres of the sea and plenty of calcium carbonate in the local rocks.

Ian

 

[Nathan Potter]

In Texas where the city water is quite alkaline and contains a lot of calcium there is definitely residue left on film after all the processing steps. It consists of particles and organic oily residue like some sort of protoplasm. The organic stuff varies seasonally. This all confirmed by lab analysis from SEM and optical microscopy of film pieces. I installed 3 in line sequential filters after the mixing valves. The first 5 to 15 um from Home Depot; the second 1 to 5 um from Home Depot; the third a nominally 0.22 um Millepore filter. This combination leaves essentially no visible residue on evaporation. The 0.22 um is probably overkill but I like clean negatives. The Home Depot filter solution by itself seems pretty effective.

Nate Potter, Austin TX.