spoel chemie

[gary mulder]

Zowel natrium carbonaat als natrium bi sulfiet kan gebruikt worden om sneller fixeer te kunnen uitspoelen. Echter ik lees dat het hier gaat om broomolie proces. Beide hulpmiddelen ter bevordering van het uitspoelen veranderen de hardheid van gelatine. Dit is niet wat je wilt bij het broomolie of olie druk proces. Je maakt daarmee juist je gelatine matrix kwetsbaar.

[Роберт]

20g Natriumsulfiet
5g Natrium of Kaliumbisulfiet

In 1 ltr. water oplossen.

De bisulfiet verlaagd de pH om het zachter worden van FILM emulsies te voorkomen. Werk je met papier dan kun je het bisulfiet weglaten. Je krijgt daardoor zelfs iets meer glans.

Of dit gebruik verstandig is bij het broomolie proces kan ik niet beoordelen.

De inflatie voor Soda is overigens ook toegeslagen: Kost inmiddels iets meer dan een Euro per kg. (Deca-hydraat Natriumcarbonaat). Dus 27g/ltr. nodig voor een 1% oplossing.

[dorff]

Thanks dorff, I understand what you mean now, and it could very well be true, no reason to doubt you. Just curious: do you make your own hypoclear or do you buy it as a finished product?

Thanks also for detailing your workflow with negatives. It seems thorough enough for sure.

Sander

I started using Kodak Hypoclear, but nowadays I make everything myself, as I have all the chemicals available. For proprietary products I either have to import, or drive some distance to Johannesburg. For something as trivial as hypoclear, it isn't worth the effort, especially since it is so easy and cheap to make.

[van eynde ludo]

dorf , can you git the formula for the hypo , to make it myself.
Thanks , ludo.

[dorff]

dorf , can you git the formula for the hypo , to make it myself.
Thanks , ludo.

Will post as soon as I get a chance to look it up.

Edit: Here it is. Stock: 200 g sodium sulphite, 40 g sodium metabisulphite, water to make 1 liter. Dilute 1:9 for use. Alternatively, 20 g sodium sulphite, 4 g sodium metabisulphite and water to make 1 liter, use as is.

The latter should cover a good number of films, and it is probably not necessary to make a stock solution. I must try and find out what the chemical mechanisms are that makes sulphite effective to remove fixer. Nearly all fixer formulas contain sulphite or bisulphite in varying quantities, so I am starting to doubt that it is a chemical reaction with the thiosulphate. It may have to do with elevating the solubility of the silver halide salt complexes. Anyway, a chemist can explain that one to us.

[van eynde ludo]

THanks , Dorff

[Rafal Lukawiecki]

The sodium sulphite is not chemically as effective in reacting away the thiosulphate, for that the metabisulphite is needed. My understanding is that the sulphite component in hypoclear is there to prevent unnecessary oxidation of metabisulphite, i.e. to extend the shelf life.

Sorry for using English, as I have no working knowledge of Dutch, Flemish, or Afrikaans—I bumped into this thread by accident. According to Anchell's The Darkroom Cookbook, 2nd ed, page 254, the ingredient that does the job of helping diffuse fixer out or paper and into the HCA solution is sodium sulphite. Sodium bisulphite is described as an optional ingredient, used to lower the pH in order to prevent softening of the emulsion of film. Anchell further suggests that if paper is to be used, the bisulphite may be left out in order to improve the paper's gloss. And on another note, sodium bisulphite and sodium metabisulphite are not the same thing, although both can be used for this purpose, weight-for-weight. I believe Ralph Lambrecht Way Beyond Monochrome suggestions go along similar line of thinking. In general, I understand that there are many formulations for fixer rinse aid. Originally it was discovered aboard seagoing ships, where sea water proved to be better at clearing fixer than drinking water was.

[kroon]

Hallo

zoek op darkroom cookbook en er komt een link naar steve anchell zijn boek in .pdf


met vr groeten
kroon

[Rafal Lukawiecki]

The recipe from the book is:

Water at 52C, 750 ml
Sodium sulfite, 200 grams
Sodium bisulfite, 50 grams (optional for paper)
Water to make 1 liter

This makes stock solution. To make a working-strength HCA solution, dilute 1 part stock to 9 parts water. The book is good, and you can find it here: http://www.amazon.co.uk/The-Darkroom...dp/0240810554/

I have both the 2nd and 3rd editions. I would be happy to sell the 2nd edition, PM if interested.

[Роберт]

According to Anchell's The Darkroom Cookbook, 2nd ed, page 254, the ingredient that does the job of helping diffuse fixer out or paper and into the HCA solution is sodium sulphite. Sodium bisulphite is described as an optional ingredient, used to lower the pH in order to prevent softening of the emulsion of film. Anchell further suggests that if paper is to be used, the bisulphite may be left out in order to improve the paper's gloss.

The recipe from the book is:

Water at 52C, 750 ml
Sodium sulfite, 200 grams
Sodium bisulfite, 50 grams (optional for paper)
Water to make 1 liter

This makes stock solution. To make a working-strength HCA solution, dilute 1 part stock to 9 parts water.

Роберт
20g Natriumsulfiet
5g Natrium of Kaliumbisulfiet

In 1 ltr. water oplossen.

De bisulfiet verlaagd de pH om het zachter worden van FILM emulsies te voorkomen. Werk je met papier dan kun je het bisulfiet weglaten. Je krijgt daardoor zelfs iets meer glans.

Thanks for repeating my answer in English in the DUTCH forum. In this way people can better stop reading in Dutch. The English part is for English talk and please keep the Dutch part for the Dutch language.