Question about Trisodium Phosphate

Steve Goldstein · May 31, 2017

The "TSP" sold in the local big-box stores is actually 75-80% Trisodium phosphate dodecahydrate and 20-25% Sodium sesquicarbonate (the box doesn't list the composition, but it's in the manufacturer's MSDS). An old formula for a glycin-based developer calls for TSP. Is the presence of Sodium sesquicarbonate significant?

I've checked Artcraft Chemicals, Photographers' Formulary, and Bostick and Sullivan. None of them sell TSP. The Chemistry Store has it, with a minimum order of 8 pounds that'll end up costing more to ship than the chemical itself. Where else might I find pure TSP?

trendland · May 31, 2017

Steve Goldstein said:
The "TSP" sold in the local big-box stores is actually 75-80% Trisodium phosphate dodecahydrate and 20-25% Sodium sesquicarbonate (the box doesn't list the composition, but it's in the manufacturer's MSDS). An old formula for a glycin-based developer calls for TSP. Is the presence of Sodium sesquicarbonate significant?

I've checked Artcraft Chemicals, Photographers' Formulary, and Bostick and Sullivan. None of them sell TSP. The Chemistry Store has it, with a minimum order of 8 pounds that'll end up costing more to ship than the chemical itself. Where else might I find pure TSP?

Just to get sure do you mean Na3Po4
CAS.7601-54-09 ? Because it is a quite
simple compound.

with regards

trendland · May 31, 2017

Perhaps your formular should work also
with an other "phosphat" if you're able to get it more simple.

For example K3Po4 - but bewahre of -
I would not trust me to give such advice
in regard of your glycin formular.
Because I never worked with glycin - sade of.
Perhaps P.E. has an answer to you ?

with friendly regards

P.S. I have to try out first pyro developer.

trendland · May 31, 2017

Sorry I should say it probably will not
work due to its ph .

It was just an idea - sorry.

with regards

Steve Goldstein · May 31, 2017

Trisodium phosphate dodecahydrate = CAS 10101-89-0

Sodium sesquicarbonate = CAS 533-96-0

trendland · May 31, 2017

Steve Goldstein said:
Trisodium phosphate dodecahydrate = CAS 10101-89-0

Sodium sesquicarbonate = CAS 533-96-0

Ok - I see this is not looking as a quite
simple compound.
Now I can imagine your problem.
I just have to check it but it seams to be so you'll need an expert.

with regards

trendland · May 31, 2017

H24Na30 16P - sorry but this is off topic
to me. I give up - I can't understand this
special chemical reaction?
Perhaps when I first read some books
about - but not just from mind.

with regards

trendland · May 31, 2017

Today is not my day : H24 Na3 O16 P
same procedure as from above.
White Flags

!

with friendly regards

trendland · May 31, 2017

michael_r said:
Formulary sells it:

http://stores.photoformulary.com/sodium-phosphate-tribasic/

Yes - but I gues we was on that point
20 min. ago.

with regards

Steve Goldstein · May 31, 2017

michael_r said:
Formulary sells it:

http://stores.photoformulary.com/sodium-phosphate-tribasic/

Thanks, I didn't think to look under the alternative names. Problem solved, I'll get the good stuff.

trendland · May 31, 2017

Steve Goldstein said:
Thanks, I didn't think to look under the alternative names. Problem solved, I'll get the good stuff.

Perfect - so your glycin formula is still
working with ordinary Trisodium Phosphate (Na3 Po4).
Problem solved.
I am not sure about the compound you
mentioned in regard of your local big-box
store (trisodium phosphate dodecahydrate H24 Na3 O16 P [70-80%] and sodium sesquicarbonate
Na3 H(Ch3)2 x 2H2O [20-25%].
But as I saw 3 min. ago sodium ses-
uicarbonate is a modern substitute of
Borax.
So your "big-box" dealer has it in addition as ph-buffer.

bon chance to developement

Gerald C Koch · May 31, 2017

Some years ago the EPA reduced the amount of trisodium phosphate that could be present in products marketed as TSP. Phosphates are a serious source of pollution as they encourage algae and plant growth in waterways. While sodium sesquicarbonate is a good alkali for developers it will not achieve the same pH as TSP will. However in the mentioned use using a available TSP will have little effect on the developer. Perhaps slow its action a bit.

Remember that if you use a hardening fixer containing alum with a developer containing TSP you must also use a citric acid stopbath to prevent aluminum phosphate from precipitating out..

trendland · May 31, 2017

Gerald C Koch said:
Some years ago the EPA reduced the amount of trisodium phosphate that could be present in products marketed as TSP. Phosphates are a serious source of pollution as they encourage algae and plant growth in waterways. While sodium sesquicarbonate is a good alkali for developers it will not achieve the same pH as TSP will. However in the mentioned use using a available TSP will have little effect on the developer. Perhaps slow its action a bit.

So it is indeed a question of ph .
Thank you much for this addition
information Gerald.
I was a lousy college student while instruction in chemestry!
But I got very high marks - caused from
all others. (they were more lousy).

with greetings

Question about Trisodium Phosphate

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