Gold toner going black

I am dipping my toes into Kallitype printing. Very interesting. Would like to try gold toning the prints, and based on a description I read on this forum (from @revdoc posted January 23) I settled on Clerc´s formula, and mixed up the Na-thiourea, tartaric acid and NaCl in demineralised water. Used 20 ml of this fluid, and added 20 drops 1% gold chloride. The mixture turned black. The black stuff turned to particulates when I poured it on the print. What is going on? The salt is sea salt (maldon sea salt). It states on the box that it is pure NaCl (no additives).
I found a gold toner recipe on the unblinking eye site, from Sandy King, that doesn't contain salt. For the chemists - what is the purpose of the salt in the original recipe?
Feedback is very much appreciated.

Torleif

I cannot comment on your specific problem, but from a lot of cooking experience I can comment on Maldon (and other) salt. "Pure MaCL" means no additives. It does not mean 100% or chemically pure. For culinary salt, "pure" generally means tha that there is no iodine or anti-caking ingredients addded. So it's natural and closer to chemical purity. Maldon is great salt and is made by precipiatating seawater; it has trace minerals in it. I would not consider it the best option of use in chemistry. Here is an analysis of Maldon salt, which I find a lot of reading but quite fascinating:



If you can use it for photographic chemistry, that's great. If not, use it generously as a finishing salt... sprinkled on top of your favorite meal. Maldon is particularly good as a topping on meat.

Hi Brian, thank you - I clearly see that I have to find another source of salt. Based on the link I see that Maldon salt is a mixed breed - I fully agree that it is a nice topping in the culinary sector

Here is another article worth reading. If I were using culinary salt for chemistry, I'd consider using plain (non-idodized) table salt. Not sure what brands are available to you; in the US the most common brand is Morton, which is said to be more chemically pure than all others. https://www.mortonsalt.com/home-product/morton-table-salt/ Table salt is highly refined. I think 99% pure is an oft-cited claim but I couldn't verify on the packaging because even the non-iodized version has anti-caking ingredients. Maybe there's another on that our markets don't stock.

BrianShaw said:

. Not sure what brands are available to you; in the US the most common brand is Morton, which is said to be more chemically pure than all others. https://www.mortonsalt.com/home-product/morton-table-salt/

Click to expand...

Probably Mortensen's in Norway

pentaxuser