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Gold Chloride

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Site Man
Posts: 573
Joined: Sun Mar 13, 2005 1:03 am
Location: Marlborough, MA

Gold Chloride

Post by Site Man »


Posted by Chris Owen on December 21, 2002
During the past 38 years, my work-life has alternated between two diverse professions, recovering and refining precious metals from scrap and making hand-carved, gilded signs. The union of these two have produced an interest in Angel Gilding, especially in the production of the gold chloride. The last step, the re-fining, the purification, of the recoveredgold usually requires it to be dissolved in aqua regia - 4/1, hydrochloric/nitric acids. The result is gold chloride. I've probably made 100,000 troy ounces of this gold chloride in my lifetime.

If anyone is interested, I could probably work up a safe system, with common ingredients, whereby most anyone could make their own, and/or a more sophisticated system for larger volume. I would, of course, follow the Letterhead spirit and not accept any financial gain for this. It is a challenge. I see it as published publicly as a thread. It seems like Rick's death has put a hitch in this technology and I would hate to see it lost, or even hindered.

There are 2 different gold compounds that are commonly called "gold chloride". One is the true gold chloride, AuCl3. The other is the "gold chloride" of Commerce, HAuCl4. The latter's true name is chloroauric acid.

The AuCl3 is made, commercially, by reacting chlorine gas with 24K gold leaf or gold powder, at 200 deg.C, probably in a pyrex tube in a tube furnace. When dissolved in water, it produces a brown-red solution. When hydrochloric acid is added it produces yellow HAuCl4.

HAuCl4 is made, commercially, by dissolving pure gold in aqua regia and subsequent cooking down to eliminate the nitric acid. It produces a beautiful yellow solution, especially when concentrated.

Does anyone know:
1) Which form of "gold chloride" is used in Angel Gilding?
2) What is the color of the gold solution?
3) What is the pH of the solution?
4) What is the gold concentration of the working solution?
5) Are kits available today?
6) Do you have any technical information concerning the reducer? Is is standard tin chloride solution?
7) Is there any palladium chloride used in the process?

Thanks in advance,
Chris Owen
Sarah King
We finally did it - we got the website up and running - www.stainedglassltd.com - if anyone is interested in Angel Gilding and other mirroring supplies.

Merry Christmas and a Happy New Year to all from Rawson and Evans' hometown - Chicago.
Robare M. Novou
Chris, Welcome to the Letterheads and Gold Chloride 101.

It appears you are welled versed in the reclamation of gold from scrap, so much so that you have made $40 million dollars from your 100,000 troy ounces, brother, could you spare a dime. I know some fund raisers that would love to talk to you!

I and others would love to see you come up with a safe system by which one could make gold chloride.

Ricks death did not put a hitch in the technology, it simple caused a void in availability of angel gilding kits, of which he produced and sold.

As to date, there are now 3 sources of these gold chloride gilding kits. Peacock Labs, Sara King, and from what Ive been told, Esoteric Sign Supply.

As to which type of gold chloride is used in Angle Gilding, I am under the assumption that it be AuCl4.

As to the color of the gold solution, it would depend on what source you bought it from. Esoterics Gold Solution was a bright saffron yellow. (some refered to it as urine water)

As to the ph of the solution, Im guessing that you are refering to the gold solution. And that you if you are again refering to the working gold solution, it may vary, ricks was acidic.

As to what was the concentration of gold in the working solution, this also varies. It could be 1 gram (more or less)per ounce of working gold chloride fluid depending on the formula one uses.

As stated before kits are available.

There are many sources for technical information concerning the reducer just as there are many types of reducer. And no it is not tin chloride solution.

There is no palladium chloride that I know of at this time used in gold chloride or angel gilding.
You will have to eliminate it from your scrap recovery of gold before you can use your reclaimed gold in gold chloride or angel gilding.

I and others would love to see you come up with a method of recovering gold from scrap. Before becoming versed in the art of gold chloride I was a normal leaf gilder. All my scrap(skewings) went into a container for use on carved signs. What old gold I scraped off of office doors and lawyer windows always went into another container for reclamation at a much later date(that date has yet to come),as I was always told that reclaimers would buy this from you. Along came gold chloride and its production methods...disolving gold in acid, was great if you knew how much gold in grams you started with. The tough part is disolving down an unknown amount in grams of used gold with all its back up paint and varnish still clinging to it, dont get me wrong, the gold does come away from all the paint and crud, heck, I even threw in some "Sign Gold" that my vinyl shop friends throw away. If only they knew! Shhh dont tell them.

This is where my experience comes to an end, as I have not yet measured the dryed bits of gold reclaimed from scrap signs. Im still lacking the complete info that could be relied upon for proper reclamation of ones scrap gold.

I do have information on this process from several sources. I just havent had the time to figure it all out in a clear and consise way yet.
Im hoping to do so sometime next year, I just got my gram scale the other day. If you got your process down pat, then by all means, do post it here. A lot of letterheads myself included would be most thankful.

Chris Owen
Thank you for your response.

From the information you've provided, it seems that the material must be HAuCl4. It's yellow and it's acidic. AuCl4 doesn't exist, except as an ion.

Gold-leaf scrap is always a problem. You have a pile of gold-containing organic scrap and you have NO idea of it's value. As I se it, you have 4 choices.

1) Send it to a refiner - as is. This is scary because the refiner knows that you have no idea of the value. When he counts your money for you, he is in a position to pay you whatever he wants to pay you. I could recount all sorts of horror stories.

2) Before sending it to a refiner, you could try to upgrade it by getting rid of some of the garbage and making it more homogeneous. The refiner would see what you have done and will be more prone to treat you fairly. Just remember that the refiner has to eat, too, and that the stuff you're selling him is not that easy to process. Upgrading involves, at least, burning to white ash and blending. This is not easy because the gold-leaf wants to fly away. Once burned, try to crumble the gold and blend it with the ash. One might be able get rid of some of the ash with acid - maybe even hot vinegar would work. Then, filter, rinse, dry, and blend. You could even torch melt this product and make a bar.

No matter how far you've gone in this scheme, you still must deal with the refiner. First off, send a gram of homogeneous sample to an assay lab. If they charge more than $25-$30, keep looking. You might find a lab with an AA and get it done, fairly accurately, for about $15. Weigh your material on a gram scale and record the weight. Once you have a good estimate of the value, call 2 or 3 refiners and tell them what the material is and that you sent a sample out for assay. Don't tell them your lab's results. Tell them how you'll do the deal. You send them the material. They open it and sample it and determine it's value. They MUST agree to NOT process the material until you have settled on the price. If you can't settle, they send it back. They may charge you for their assay. Find out their total charges before you ship it. If you have a lot of scrap, you might split your lot among 2 or more refiners. You will find that the large refiners may be more honest but are less apt to deal in this manner. They usually have a minimum charge of $250, or more.

3) Refine it. That's how I would do it. Of course, I have a lab, the needed chemicals, equipment, and fumehood, and 38 years experience. Refining is easier said than done. The only advantage of refining is to get top dollar for your gold. The disadvantages are many. It's dangerous. It produces heavy dark red-brown fumes which are very unpleasant to breathe and will rust any steel it comes it contact with. Did I mention the toxic heavy metal waste that is produced?

4) Use it to make gold chloride. You first must dissolve it in the same chemicals and will have the same problems as in (3) above. Before dissolving it, you would burn it, to get rid of the paint, etc., and expose the gold to the acids. Unless you have 24K leaf, you would probably have to fully refine it (re-fine it; make it fine, or pure, again). Otherwise, the added alloy metals could foul the gilding.

If I were in your shoes, I would try (2) above with your scrap.

For the gold chloride, I'd start with pure gold powder, if I were using something like bleach/peroxide or hydrochloric acid/peroxide to dissolve the gold. Pure gold powder is created, as a matter of course, in the aqua regia process used by most refiners. The powder is then melted, cast into bars, and sold. Ask the refiner to pull out some of this powder before it's melted, dry it, and sell it to you. A fair price would be about$10 to $20 over market price, per troy ounce. The purest powder is light tan to medium brown. Less pure powder is darker, although pure can be dark, also. If you put a speck on your finger and rub it on a glass, pure gold powder quickly burnishes to a brilliant gold color. Lesser purity gold burnishes slower with less brilliance. If I were using aqua regia to dissolve the gold, I would use gold Maple Leaf's or American Eagles or powder, all cheap sources of pure gold.

Back on gold scrap, it may be better to co-op the scrap, somehow, and try to find someone that knows what's what and can be trusted to handle it. This way, larger amounts can be shipped to the refiner and a better deal can be cut. The handler can physically watch the refining of the material and can pull pertinent samples during the process, in order to keep the refiner honest. This only works with large volumes.

Do you know what the reducer is made of? A tartrate? A lactate?

Chris Owen

Robare M. Novou
Ah yes, it is indeed HAuCl4.

Some of your discribed choices for refining scrap gold are more suited for large amounts of scrap.
And the burning of the scrap would not neccassarily be required.

Ive been reading information about those who refine gold from scrap circuit boards, and all the heavy metals they have to deal with. Most gilders would have far less to refine. And for the most part the only impurities would be silver and copper.

I use a 2:1 ratio of auqa regia in a plastic gallon milk jug. I sheread up all my scrap gold and place it into the jug. I then place about a cup of auqa regia into the jug. It doesnt take much. I cap the jug and swish it up a bit, all the gold dissolves off the tissues, scrapings, and pieces of wood letters.

In only a few minutes I am then left with yellow liquid, which is the disolved gold. I can pour this fluid into a flask and cook off the acids, let cool, after which I am left with almost pure gold in cyrstal form.

From here I can refine it further. By adding water and some other chemical I can take out the silver. Filter it and end up with pure gold. With which I can use in solution gilding.
Its a multistep process, and I think its called washing the gold. Like I said before I have all this info on it, and I just skimmed over it. I haven't had the time to go into a detailed reading of it. And I no longer have to deal with the brown fumes.

As far as what type of gold to get to liquify, I have suggested using canadian Maple leaf coins.
Because they are pure gold. American Eagles I believe contain Silver so you wouldnt want to use those.

Lately I've switched to gold bars in 10 gram sizes. They're less costly than the coins, but still pure gold. Ive been told about gold jewelers shot which is even lower in cost than the bars. My cost per gram with the bars is around $13 per gram. check the internet or coin and or jewelery stores.

So as you can see its a relatively simple process.
I've done it several times, but never had enough gold from scrap in solution to produce a true 24k
gild. From gold bars yes, but not from scrap, not yet.

This is where I need to do further research and get the crystal form into a powder form to weigh out into grams.

And yes I do know what the reducer is.
No, its not a tartrate or a lactate that Im aware of. Although a definition of a tartrate is salt of tartaric acid, widely found in plants, grapes being one such source. And as I seem to remember, some formulas called for dextrose as a reducer, dextrose being a grape sugar. I tryed dextrose and didnt like the results.

Lactate, another salt, of lactic acid. No I havent tryed it either.

Chris Owen

You're right about the Eagles. They're 22K and contain about 3% silver and 5% copper. I think that the pure ones are the Maple Leaf, Chinese Panda, Credit Suisse, and Pamp bars.

Four nines pure gold shot is used by most jewelry manufacturers, since it is cheap and the small pieces makes it easy to weigh out. The cheapest place to buy shot is from the person that supplies the jewelers. A supplier in Houston is Eagle Jewelry on Westheimer. Ask a jeweler where he buys his shot - he probably will tell you. Shot goes for about $3 - $8 over market, per tr.oz., depending on how much you buy.

Don't overlook pure gold powder from a refiner. It may be a little more expensive than shot, but it is much more convenient to use as a starting material. It dissolves about as fast as leaf. In fact, it goes so fast that boilovers can occur. This is remedied by feeding either the acids or the scrap slowly, in increments. The best way is to add your hydrochloric and a little water and heat. Then feed the nitric slowly, in increments. Go slow. When you add nitric, the solution will fizz and foam up, a lot. As the nitric is depleted, the foam subsides and you can add another shot. If you add nitric and get no fizzing or foam, either the gold is gone or you need more hydrochloric. Remember, that 99/1 - hydrochloric/nitric and 1/99 - hydrochloric/nitric and any mix in-between will dissolve gold. All the books and most refiners use premixed AR. I find it best to think of the acids as 2 separate entities. I use the very same method for solid gold, pure or scrap.

If you used powder, you might be able to do the whole thing, from dissolving to finished product, in about an hour, or two. Here's a clean way to do it. The same process is good for solid gold but, as you know, it will take several hours, at least, just to dissolve the gold.

Theoretically, it takes about 120 mL of standard 4 to 1 aqua regia to dissolve 1 troy ounce - 31.1 grams - of gold. This breaks down to 96 mL of hydrochloric (muriatic) acid and 24 mL of nitric acid. This varies a little due to temperature and the strength of the acids that were bought.

1) Start with a very small test batch. Calculate how much hydrochloric you'll need to dissolve only 95% of the gold in the batch. Calculate the nitric for only 90%. Measure out these amounts. Technical grade acids are much cheaper and work fine. They vary more in concentration, however.

2) Cover with all the hydrochloric acid plus about half as much water. Heat til pretty hot but not boiling. Never boil. If you do, you can't distinguish between boiling and fizzing.

3) Add about 5-10 mL of the nitric that you measured out. When the foam subsides a little, carefully give it a stir - it will foam up fast, if you stir too vigorously. Add another shot of nitric. The idea is too dissolve the gold as fast as possible without it foaming over. Repeat until all the measured out nitric is gone. Heat until there has been no fizzing for 15 minutes, or more.

At this point, you should have a pure, strong, gold chloride solution, containing about 5% hydrochloric, NO nitric (think about it), and 5% of the gold, sitting on the bottom. When cooled, diluted 3/1 with water and filtered, any dirt and silver and excess gold is removed. The residue, filter paper and all, can be put into the next batch. The result is ready-to-go concentrate. If the hydrochloric is too high, add, say, 1% or 2% more nitric next batch.

The purpose of cooking down is to remove the acids, especially the nitric. Cooking down is not easy and requires a special feel to do it right. Angel gilding will probably work with a little hydrochloric but with no nitric. Nitric could re-dissolve the gold. This system could eliminate cooking it down.

For the other readers, this is one of those "don't try it at home" things. Aqua regia is corrosive to lungs, skin, eyes, clothing, and most metals. The fumes are choking and must be controlled. If anyone wants to try it, though, let me know and I will try to guide you through it.

About using scrap, I would think that the copper would cause gilding differences. It might be OK with 23K or 23 1/2 K, but could cause problems with the lower karats. At the least, there would be the problem of an inconsistent product. If you were to drop the gold out the AR, as powder, with something like sodium sulfite (photo supplies), then filter, rinse, and re-dissolve, it would solve these problems. Only the gold drops out. The copper stays in solution. If you did this, you could even use scrap karat gold jewelry as your metal source.

You could also dissolve gold powder or leaf, but not solid gold, in some hot mixture of strong hydrochloric and VERY small additions of hydrogen peroxide. 30% H2O2 is best. You might be able to use the 6% sold in beauty supply stores, but 30% is best. The 3% from the pharmacy is nearly worthless. Be careful with the strong peroxide. It will quickly burn your skin and eyes. If you add too much at one time, it will definitely foam over and get very hot. Any excess peroxide is converted to water. No nitric is used. No brown fumes. A very clean process with clean results.

How is the reducer made? E-mail me if you like. Tit for tat?

Chris Owen
Chris Owen
Here's a copper Angel Gilding-type solution that I found on the internet.

Copper Sulfate - 15 gm/Liter
Formaldehyde - 10 gm/L
EDTA - 20 gm/L
Sodium Potassium Tartrate - 10 gm/L
Sodium Hydroxide - 15 gm/L

The sensitizer is stannous chloride, the same thing used for Angel Gilding. Palladium Chloride can also be used.

Chris Owen
Chris Owen
It may be interesting to note that stannous chloride (tin salts) is commonly used to test for the presence (is or isn't) of gold in an aqua regia or chloride solution. A drop or two of the solution to be tested is placed on a piece of filter paper (or a small beaker or a spotplate) immediately followed by a drop of a fairly strong solution of stannous chloride. If gold is present, you will see the most beautiful purple appear. It is the color of collodial gold, Purple of Cassius. Coincidentally(?), it is the same color as a king's robe. If you've Angel Gilded without gloves, you've gotten it on your hands.

The standard way to preserve these test solutions of stannous chloride is to keep a small piece of mossy tin in the solution.
Chris Owen
Here's an Angel Gilding formula I ran into from Bruno Schweig's book, "Mirrors, A Guide to the Manufacture of Mirrors and Reflective Surfaces".

There are 3 solutions:

Solution 1

Gold Chloride 5 gms
Selenium Dioxide 7.5 gms
Distilled Water 1000 mL

Solution 2

Sodium Carbonate crystals 50-60 gms
Distilled Water 1000 mL

Solution 3

Formaldehyde 75 mL
Distilled Water 1000 mL

For use, equal quantities of solutions 1,2, and 3 are mixed together.

Chris Owen
Robare M. Novou

Ive a question about how ingredients are measured out in this formula...

the measure of "ml" would be a liquid by volume?

and the measure of "gms" would be a dry powder or crystal by wieght?

Any specifics would be appreciated

Chris Owen
Correct, in these particular cases. Some formulas use weight for the measurement of liquids, also.
Mike King
As a chemist from way back, here's the way I use "ml" for "millilitres", "cm3" for "cubic centimetres" and "g" for "grams":

1.0 g of, say, elemental gold (100% pure) is very well-defined and means only one thing, whether the gold is shot, molten, vapour (rather hot!) or whatever.

1.0 cm3 means the volume of a cube of 1.0 cm on each side. This used to be called a "cc" but the Politically Correct form of this is now "cm3". 1.0 cm3 of the gold above is not very useful as there would be no easy way to actually measure it. I, for one would hesitate to measure out 1.0 cm3 of gold vapour.

The meaning of "litre" is temperature and pressure-dependent and specifically means the volume of 1000 cm3 of pure water at 1 atmosphere and 4 degrees C. This means that a litre is different on the top of Everest or the Space Station. Again, I would avoid measuring the volume of a sample of gold on the Space Station - there are more important things to do there!

Of course, we all understand that the 1.0 g we are talking about is a "mass" and not a "weight". On the Space Station that 1.0 g would be almost weightless but still 1.0 g. We also all understand that "litre" is the way Napoleon would have spelt it when it was invented but Americans spell it "liter".

Realistically, we measure weights and volumes using grams and millilitres at normal temperatures and pressures.

As for when to use each, _ Schweig would have been very familiar with the issue and it would not have been a problem: use weights when you can and volumes otherwise. It is easy to weigh solids with a balance so long as they are not hygroscopic (absorb air-moisture), do not readily evaporate and the weight is somewhere between 1.0 mg and 10.0 kg. It is also easier to measure out 10.0 ml of distilled water than 10.0 g since you would have to put into a container and subtract the weight of the container (tare weight). By the same token, gases in cylinders are measured by weight since the liquid propane or oxygen inside has a very variable volume.

So the answer is: it depends (sorry - I used to be a computer consultant!)
Robare M. Novou
Points well taken! Thank you.

When weighing out gold chloride of the hyroscopic variety,(crystal form) how should one do so, to prevent the mass from absorbing moisture...and is the amount of moisture that it absorbs dependent on relative humidity during the weigh-in session?

And would the amount absorbed(small or large) affect the formula production process?

I've read where those who have used gold chloride in cyrstal form, talk about it becoming sticky and sticking to thier fingers and whatever they touched. Sounded to me like sloppy handling of the material. The one time I did use the premade crystal form, I dumped the contents of the vial into my premeasured distilled water, and then rinsed out what ever was left in the container so that I was not disposing of any gold. No sticky fingers. When you pay $70 for 1 gram of 60 percent gold chloride, you dont mishandle it.

When making gold chloride solution for solution gilding, I don't think one needs to measure out the crystal and then apply it to whatever formula your using.

I would think that you just add your water to the cyrstal you just made, using your previously choosen formula as a guide for how much water to add. You now have gold chloride solution, There by eliminating the need to handle the crystal.

I would guess that the reason one needs to handle
the crystal is for selling in 1 gram or more lots.

Mike King
Weighing out those things outside of the "norm" usually involves some simple modifications to the substance in question and some arithmetic.

To weigh something really small or hygroscopic that you are planning to dissolve in water anyway, weigh a larger amount of the solid and dissolve in a larger amount of water but in the right proportion. The solution then has the right concentration but you need to measure out (in ml) a smaller volume of the result. If the solution keeps, you just need to store away that portion you don't use. This is the approach to take when you need to send someone else "the right amount" of a solid that will later be dissolved anyway. By dissolving it in water first, you are then sending the other party some water with their solid which may seem unnecessary but it has the benefit that they can then measure by volume and only have to dilute it to taste (so to speak).

It also solves the issue of what exactly you are working with. Yellow gold chloride in its solid form is actually a "hydrate" - a chemical compound with attached water molecules. The result is a wet crystalline substance whose chemical formula is not very exact. It works the same way as Washing Soda which is technically "sodium carbonate hydrate". It comes in big wet crystalline lumps which are chemically the same as that white powder known to chemists as Sodium Carbonate CAS 497-19-8 but with extra water molecules stuck to the sodium carbonate molecules. Weighing this stuff is tricky because it's hygroscopic and doesn't have an exact chemical formula. The answer with the gold chloride at least is to start with a known quantity of gold and make sure you don't lose any of it. You then dissolve it in water so you can work with it.

Robare M. Novou
I concur,thank you, now could you provide an example of a gold formula that uses weight as a measurement.
Chris Owen

The whole thing is arbitrary and depends on what is more convenient. Gold chloride can be made in two forms, dry crystals or crystals dissolved in a solution. In the formula I posted, the author assumes the use of crystals. If your gold chloride is in solution form, you have to calculate how much of the solution it would take to equal the dry weight called out in the formula. Of course, to do this, you need to know the gold concentration of your solution.

For example, let's say your solution contains 50 grams of gold metal per liter (1000 mL) of solution. Since gold chloride, HAuCl4, contains only 65% gold metal, you have to take that into consideration. The concentration of your gold chloride would, therefore, be 50 divided by .65, or 77 grams of gold chloride per liter. The formula calls out for only 5 grams of gold chloride. The amount of gold chloride solution required would, therefore, be 5 divided by 77, or .065 liters. One liter equals 1000 mL and, therefore, you need to add .065 X 1000, or 65 mL of your gold solution to make up the bath. Since your gold solution is mostly water, you need to reduce the amount of water in the formula by 65 mL. The amount of needed is 1000 - 65 equals 935 mL.

With your 50 gm/L gold solution, your formula for making up solution #1 is now:

50 gm/L gold solution - 65 mL
Selenium Dioxide - 7.5 grams
Distilled Water - 935 mL

Chris Owen
Robare M. Novou
Thanks for the great information! Mike Jackson said I was "the man"...News Flash, Chris, "You the Man"!!! You're the right guy at the right time! Your expertise is astounding, you have contributed a wealth of knowledge that will advance the letterhead movement and better the current understanding of solution gilding by those who use it. Thank you so very much.

Heres some other questions you should be able to answer.

When buying gold chloride in crystal form or making it in crystal form, how can one be sure its at a certain percentage? I noticed some formulas call for 84 percent gold chloride.

Venders sell 1 gram gold chloride in different percentages. How do they achieve a gram of 64 percent and another gram at 50 percent?

And what is the maxium percentage of gold per gram that can be produced in crystal form?
Ive never seen it offered at 84 percent, I think the highest I saw was around 70 percent.

You deserve a gold medal...on second thought, I'd hold off on giving you a gold medal, as you would just make gold chloride out of it. I know I would ;)

Chris Owen
I made an error on my last post and hope this will correct it. I said that the percentage of gold in HAuCl4 was 65%. Not true.

Actually, there are only 3 types of gold chloride to be concerned with.

1) AuCl - 84.7% gold - true, valence +1, gold chloride - pale yellow powder - Made by heating AuCl3 - water converts it back to AuCl3 - Not what you would buy for Angel Gilding, although it seems it could possibly be used

While researching this in one of my books, I found this interesting quote, concerning AuCl. "It (AuCl) dissolves in alkali chloride (table salt) solutions ... These also soon undergo decomposition in solution, however, depositing metallic gold..." Remy, "Treatise on Inorganic Chemistry", VOL II, page 416

2) AuCl3 - 64.9% gold - true, valence +3, gold chloride - red needle crystals - made by reacting chlorine gas on gold leaf or powder at 200 deg.C - soluble in water and produces a brown-red solution - when hydrochloric acid is added to the water solution, the lemon yellow HAuCl4 (see below) is produced - this would probably work for Angel Gilding

3) HAuCl4.4H2O - 47.8% gold, when purchased in crystal form - valence +3 - chloroauric acid, the "gold chloride" of commerce - long, bright yellow, needle-shaped crystals - formed by dissolving the gold in aqua regia - this is what all of you are using - if you were to carefully evaporate your solution down, HAuCl4.4H2O would crystallize out.

Chris Owen

Robare M. Novou
Yep, #3 is what I make. Now can you tell me what a "valence" is? I see it here in my dictionary...and I get the feeling that it pertains to "parts" as one part gold, 3 parts hydrochrolic.

Mike King
Many large elements have the ability to form multiple compounds with a given element, the suffix "-ous" and "-ic" being used to distinguish between them.

For example, iron forms two oxides: ferrous oxide and ferric oxide. The difference is "valence" - the number of electrons that move from one atom to the other in forming the bond between the elements that makes it a molecule. In the case of gold, there are two chlorides: aurous (valence 1) and auric (valence 3). Aurous chloride has less chlorine atoms per gold atom and is called a "reduced" form and is less stable whereas auric chloride has as many as it can handle and is considered the "oxidized" form (even though it doesn't have any oxygen!) The stuff Chris correctly refers to as chlorauric acid is the result of bonding a hydrochloric acid molecule to an auric chloride molecule and hydrating it. The water molecules are what makes it stable. Some of the other metals that do this are tin (stannous and stannic), lead (plumbous and plumbic), copper (cuprous and cupric) and chromium (chromous and chromic). When these compounds dissolve in water they form "ions" which are then written with a superscript indicating the valence , e.g. Au(3+).

Mike Jackson
Hi Chris,
Are you in Santa Cruz? I don't know if I heard the name, but I heard there was someone there doing a lot of solution gilding, mostly on mirrors. Welcome to the site, whether you are that person or not.

Robare Noveau is selling a book on the subject, including several techniques and variable techniques. Rick's step by step process for applying the gold is in the Rick Glawson section. Sarah King is now producing and selling kits, and I hear some kits are being sold by Peacock Labs.

I personally used the Angel Gild process on a lot of our Glass Art panels, but I only bought the kits from Rick and used them. I never asked how he made it or the version he used.

I haven't had the time and money to try to figure out the process, but it appears several people now know how to to do it. Adding your knowledge to the collective information base is very welcome. My opinion might be contested, but I think it is time for the information to be available to all and used by anyone willing to spend the time and money to make it work.

Again, nice to see you on this Forum!
Mike Jackson : Co-Host
Posts: 1
Joined: Fri Apr 07, 2023 4:46 pm

Re: Gold Chloride

Post by Slimos »

Hello Everyone,

Im new in this forum and hopefully you can help me.

I want to make gold nanoparticles from AuCl3, im wondering about proportions used for hcl and Aucl3 to make a 25 mM HAuCl4 sokution.

Thanks in advance
Kevin Betz
Posts: 2
Joined: Sun Jul 04, 2004 4:54 pm

Re: Gold Chloride

Post by Kevin Betz »

Interesting Information
Is this about Recycling Goldleaf ?
Or, the Best Appearance ?
I do not believe you can Angle Guild on a Vertical
Window ?

Ron Percell
Site Admin
Posts: 66
Joined: Fri Apr 09, 2004 9:32 am
Location: Angie, La.

Re: Gold Chloride

Post by Ron Percell »

Gold Chloride (Angel Gilding) can be sprayed vertically.
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