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Discussion in 'B&W: Film, Paper, Chemistry' started by ann, Oct 16, 2003.
Have been shopping for gold chloride. Is anyone aware of a price less than 13 dollars a gram?
I can't really say that I'm surprised that it's worth its weight in - gold?
Aggie, as you know 22kt gold is 22/24ths gold, and 2/24ths something else. That is by weight, so by number of atoms it's about 90% gold at most.
Making gold chloride involves dissolving it in Aqua Regia (a particularly nasty mixture of nitric and hydrochloric acid). The other components must then be removed until you're left with 99% gold in the solution (pure enough for toning), and the acid removed until you're left with gold chloride only.
I would not like to try it.
Technically speaking, the correct name for "gold chloride" is "tetrachloroaurantic acid" if I remember correctly - or was it "hexachloro--"?
Try searching for the chemical under that name, sometimes it may turn up less expensive alternatives.
Ole is right. Aqua regia is about the only solution that will dissolve gold and platinum. It is composed of equal parts concentrated nitric acid and hydrochloric acid. You will probably find it easier to purchase the gold chloride than the other two nasties.
My experience with this technique is limited, but I remember a lot of fuming, heat release and the obvious requirement to work under a very specialized chemical hood. The reactions can get out of control thermally with the release of clouds of brown nitrous(ic) oxide fumes - not a pretty sight. Once dissolved, the whole mass must be neutralized with lots of caustic soda, ya da, ya da, ya da. Not an easy project and not for amateurs.
Thirdly, in these times of home-made you-know-what, the procurement of concentrated nitric acid will no doubt be an issue as it can easily be use to make you-know-whats. Lets just say that I'm glad my experience is in the far distant past in a galaxy far, far away. That is why my companions changed my nickname from "rocket bob".
Given the price of Gold Toner kits, the cheapest in my area is $26.00 I would say you price of Gold Chloride is reasonable
That is sweet of Aggie to attempt to become a high end chemist, but not necessary. At one time, about a year ago gold cholride could be found for about 7 dollars a gram. Just thought I would give it a try.
The 13 dollar price is determined by purchasing an ounce of gold cholride; price depends on the market price, which changes from hour to hour (almost). When I talked to the source it was $362 an ounce. An ounce contains 28.35 grams of gold. Sure beats $40 dollars a gram.
Appreciate folks looking into this for me.
On the subject of aqua regia there was an article in one of the early issues of Post-Factory Photography a few years ago on how to make gold chloride from gold metal and aqua regia. The article resulted in a rather animated exchange between the editor of the magazine, Judy Seigel, and Dick Sullivan of Bostick and Sullivan. There are apparently some real hazards associated with the use of aqua regia and unless one knows a lot about safe laboratory practice with hazardous materials my recommendation is to stay away from it.
Okay, it's a couple years since this thread, and the price of Gold Chloride has gone up.
PhotoFormulary--$30/gram (solid) if you buy 10 grams
Salt Lake Metals--$26.24/gram (in 1% solution calculated by metals basis--the amount of pure gold, so about a 1.5% solution calculated the way photographers normally do it, sold in 50ml or 100ml bottles)
Anyone finding better prices out there? Anyone good at predicting the gold market (currently around $470/oz)? If I can wait a month or two, should I?
Considering that gold has long been the haven of choice during times of uncertainty, I don't see gold prices declining in the near term.
I believe the ounce used for precious metals is the Troy ounce which is 31.1 grams.
Has anyone tried contacting Englehar(d)t or others that sell it fairly cheap by the 100 gram?
I think that's Engelhard. I'll contact them.
Checking the big suppliers, price depends on purity. What purity do I need for photographic purposes (I'm guessing it's less than is required for medical purposes)?
I believe Lab grade is fine. I also have another contact at work I will pull down on Monday for us.
Thanks. I e-mailed them and it bounced, so I'll try calling during the week.
Considering Ole's post above, the prices that others have been getting in the past, and the lab conditions that most photographers work under, I suspect 99% purity should be good enough.
David, I suspect purity is related to use.
In silver halide emulsions, the gold used must be pure of all other heavy metal contamination or you can get problems. For example, iron contamination at any time in the making of silver halide emulsions is very bad.
So, purity above some level may be important depending on use, and the type of impurity may be important as well. This is why analytical and reagent grades are supplied with a certificate of analysis on the bottle.
Of course. I'll be using it as a toner for albumen printing.
$13 per gm is actually very reasonable.
I went from being a Photographic Chemist in 1986 to being a precious metal refiner and have 18 years experience of Gold refining, many kilos of fine gold per day
Your price of $13 is actually well below the norm for laboratory grade Gold Chloride.
What are people using Gold Chloride for?
I was told by photographer Kim Weston, that if used about 2 drops of 1% solution in your coating for platinum prints...it will give a better black.
What else can gold chloride be used for?
Ann's original post is two years old. Would that I would have bought then.
Most people are using gold chloride in toning formulas. Gold toning is standard procedure for albumen printing and is also recommended for Centennial POP.
It makes a very nice toner as well!!
Gold chloride is use in sensitzing high speed silver halide emulsions in almost all films sold on the market today.
Cachet claimed that their Expo graded paper (same as Maco Expo, J&C Exposition Graded, Efke Emaks) had a relatively high gold chloride content.