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Sodium Tripolyphosphate

CMoore

Member
Joined
Aug 23, 2015
Messages
6,344
Location
USA CA
Format
35mm
Go ahead and laugh, but.......why did i buy this stuff.?
I want to say it is for making some kind of Perma-Wash type of washing agent.....but i do not really see this chemical listed as a typical ingredient.....maybe it is.
I certainly have not read All Of the Posts/Recipes, but this does not seem to be a part of making a Perma-Wash/HCA kind of a wash aid.
Thank You
 
Actually, you probably need some of it to make a wash aid, if your tap water is hard. Anyway, it can also be used in developers and it's not typically listed in formulae.
 
One of the main uses of this chemical is to chelate calcium and magnesium ions in hard water. If you mix your own HCA it would be useful in a concentration of 2 to 3 g/l of working solution. Another use would be in paper developers. It's pH is probably too high for use in film developers.

https://en.wikipedia.org/wiki/Sodium_triphosphate
 
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Thanks Guys..... not at a point where i am ready to make developer.
OK...so "Hard" water...which definitely applies to my house.
Would this stuff be the Same/Similar as using Sodium Bisolfite...that is to say, if i use One of these, does that me i do not need the other.?
Thanks
 
Gerald C Koch said:
... It's pH is probably too high for use in film developers...
Click to expand...
Funnily enough, it is listed as an ingredient in Perceptol, one of the lowest pH developers (< pH 8)...

No, it's unrelated to bisulfite and you don't really need bisulfite. You can use your wash aid for a single session, in which case ~2g/l sodium tripolyphosphate + 20g/l sodium sulfite are fine. The order of addition is important.
 

The proportions of the ingredients in Perceptol are adjusted for its presence. This would not be true if it were added by the user.
 
Wow...i REALLY need to be careful, as my vision (at least for reading) has gotten worse as i age.
So you are saying the Order IS IMPORTANT.
I assume then, i measure One Liter of water, stir in Two Grams of Tripoly, and after that is well dissolved, stir in 20 Grams of the Sulfite.?
Thank You
 
Yes, exactly that. If you do have hard water and dissolve sulfite first, then your washaid will get cloudy within minutes. At this point there's not much that can be done.
 
Anon Ymous said:
Yes, exactly that. If you do have hard water and dissolve sulfite first, then your washaid will get cloudy within minutes. At this point there's not much that can be done.
Click to expand...
So if that does happen, it would be better to switch to Distilled Water.?
I do have a filter on my darkroom sink, but i am not sure what exactly it filters out. Not sure how many types of "Hard Water" there is either.
All i know is that, where i live, the sprinklers (for people that actually still waste water on a lawn) bleach out a wooden fence in one year. You can see the outline of where the sprinklers hit the fence. But i do not know if THAT means the water id bad for washing RC Paper.......
 
If you scratch mix your wash aid with sodium tripolyphosphate, then there's no need to use distilled water. You already have it, so it can be put to use.

If your filter has any water softening capabilities, then mixing some sodium sulfite in tap water should create a clear solution that remains so. If it doesn't, you will notice cloudiness that will become precipitate given enough time.

Your tap water is fine for washing paper. In fact, a wash aid is certainly not needed for RC paper. A 2' wash in running water is enough. Just make sure you don't use a hardening fixer, that's an important bit.
 
OK...Thank You.
I have read the term 'Hardening Fix" several times. I am not really sure what it means, but i am pretty sure Ilford Rapid Fix is not that type.?
Thanks
 
@CMoore: raw photographic gelatin has a melting point of 20°C, and swells strongly in alkaline liquids. Hardening increases linkage of gelatin and therefore raises its melting point. Traditionally this was done by adding special compounds to fixer. Any halfway recent stash of photographic paper coming from a somewhat reputable supplier now comes prehardened from the factory, which makes hardener in fixer mostly obsolete. Typical hardeners in fixers require the fixer to be acidic, which decreases its shelf life and increases wash times, therefore stay away from hardening fixers if possible.
 
10-4...Thank You.
I HAVE read a few recipes to make my own Fix. I also did a bit of reading here...going back and reading previous posts.
But at this point, with me still having a lot to learn about photography in general.....i decided against it.
Unless it gets (becomes.?) deemed a huge Environmental/Terrorist/Shipping threat.......For the foreseeable future, i will be using Ilford Rapid Fix, or another similar product that is easy to buy.
 
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