Mixing Gold Chloride

[Festus]

Now that I finally got an image that’s a keeper, I guess it’s time to gild that puppy. At alternativephotography.com, it’s stated that you make Part A by dissolving one gram of Gold Chloride in 500ml water. Then make Part B by dissolving 4 grams of Sodium Thiosulfate in 500ml water. THEN, to make the solution Add A to B, but DO NOT add B to A, as this will ruin the solution. Whaaat? Is there some magic to making this? At 60 bucks a gram, I sure don’t want to screw this up.

And, I just bought a small alcohol lamp on ebay. Conpared to a propane torch I think the lower temperature will increase my chances for success. Just hope it arrives before this weekend, or I’ll have to chance it with the propane.

[dagist]

Festus said, “Add A to B, but DO NOT add B to A, as this will ruin the solution. Whaaat? Is there some magic to making this?”

The rule that you must always remember when mixing your working solution of gold chloride is to ALWAYS pour the gold solution into the sodium thiosulfate solution. Do NOT do it the other way around, or you will risk a black precipitate forming in your solution which will make the solution unusable until you remove the precipitate. Pour the gold into the sodium thiosulfate quickly but gently and then agitate gently to make sure it is mixed thoroughly. It is also wise to filter your mixed solution before using it.

If you accidentally do pour it together the wrong way and get the black precipitate, the gold chloride solution can be saved by mixing some common table salt into the solution and letting it sit overnight. A teaspoon of salt should be enough to clear the precipitate from 100ml of gold chloride.

Good luck with your gilding and remember to heat the plate as evenly as possible. Don’t let any part of the plate cool down during gilding (especially the perimeter), otherwise you will get visible tide-lines (swirls) on the plate where the gilding solution hasn’t acted on the image uniformly.

Cheers,

Rob McElroy

Buffalo, NY

[drdag]

for your sake, practice on a non important plate first.

[jdanforth]

Also make sure that the plate is perfectly level. I pour the solution on the plate and then use my finger to carefully draw the water along the perimeter of the plate. It’s vital that the liquid not evaporate or pour off the plate while you’re gilding.

The only advantage that the blow torch has over the alcohol lamp is speed, by the way.

This has already been mentioned but it bares repeating: filter your solution every day you’re going to use it. Months will go by where I haven’t made plates sometimes and I always filter the solution about four or five times before using it.

If you don’t filter it then you’ll get these little black spots all over the plate. I’ve heard it called Daguerreotype Measles. I think it has something to do with sulfides but I’ll leave the real answer to the scientists on the forum.

[Festus]

Good info! But what do you use to filter the solution with?

[dagist]

Festus,

I use a general-purpose laboratory filter paper. Whatman is one of the most popular manufacturers here in the US. I use a 20-year-old box of their Grade 40 ashless paper, for no other reason than I had a box laying around from an estate sale purchase many years ago. It is a classic paper for general purpose filtering with a medium flow rate and retention. It works great for me.

Whether a paper with a faster flow rate and less retention would be just as effective for gilding solution filtering, I don’t know. Maybe one of the chemistry experts among us can share their filter paper knowledge.

Cheers,

Rob McElroy

Buffalo, NY

[Festus]

Geeez Rob. I was hoping you would recommend coffee filters or something simple like that.

[Mercury]

Festus,

A cotton-ball crammed into the neck of your funnel with work, but hey, this is GOLD we’re talking about. A box of filter papers is not that expensive from Cole-Parmer or Aldrich. I’ll go with Dagist and recommend the Whatman paper. I also use it.

Cotton balls retain a lot of solution, which equals either waste or a lot of distilled water rinsing, which dilutes your gilding solution. Save the cotton balls for cheap stuff like the thiosulfate fixer. Cotton balls are adequate for that.

Coffee filters actually contribute a fair amount of particulate to the filtered solution from the “downstream” side of the filter surface. I think cotton balls are better, tho not as fast.

The Whatman paper retains very little of the filtered solution, and so can be rinsed with a few millilitres of distilled water to flush most of the good stuff down the funnel where you can use it.

Don’t disrespect the gold. I’ve f***ed up more wonderful plates trying to scrimp on gold or the things that touch it than I care to tell you about. And it hurts worst since it’s the last chemical step in the process.

Oops, I hear Miss Kitty calling…

[Festus]

Very good. I’ll make the effort to get the Whatman paper.

BTW, it’s overcast today, so no new dags. But I’ll still try to gild the one I made last weekend. Wish me luck.

[Festus]

Just mixed the gilding solution. Photographers Formulary only had a half gram in stock, so mixed it half strength….1/2 gram to 250ml water, and 2 grams Sodium Thio to 250ml water. Before mixing the two, the Gold water was a nice shape of, well, gold. After mixing the two solutions, it just looked like water. Poured into a brown bottle and set off to the side. From what I understand, it’s supposed to sit for a day. But being the person that I am, will probably try to gild the plate later today. Hopefully all this fog will burn off and I can occupy my time making another dag. I’ll run my the medical supply store to look for filter paper also.

[photolytic]

Festus

No 54 Whatman paper filters faster,and its hard finish absorbs less solution.

No need to age the solution. It’s ready right away.

In fact it’s better to make it fresh and only as much as you need for 1 plate.

Any color in the gilding solution is usually colloidal gold, a very fine precipitate which is less active in the gilding process and will eventually settle out.

If you practice pouring your gilding solution on a level plate rather than using a tray you’ll save lots of money. Approximately 80 ml is all that is required for a wholeplate.

Don’t use your fingers to spread it around as was suggested above.

Get a glass stirring rod. It’s much cleaner and won’t contaminate the solution

By the way I liked Mr. Dillon’s first deputy, Chester, with his gimpy leg.

[jdanforth]

Festus, I use coffee filters and they work fine. Recycled ones to boot. I just cut them into little squares so I don’t lose much solution to transpiration.

edit: better do what Photolytic commands you to with the finger. It’s worked fine for me for years but obviously it’s wrong. In fact, I guess you could disregard all my advice for the same reason.

[Festus]

Hey Jonathan, I’m sure if it works for you, it’ll work for me. But I did use a glass stirring rod to spread the solution. I’ve already had too many booboo’s by accidently touching the plate at various times during the process. But I’ll try the coffee filters.

Thanks.

[Author]

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