Wednesday, October 16, 2013

The Making of a Gold Pigment for the Black Hours Scroll

Recently I created a Peerage piece based on the Sforza Black Hours, which required the use of a lot of gold. When inspecting the original I came to the conclusion that the gold (and silver) were most likely applied with a brush or quill, as opposed to having been gilded.

I needed powdered gold to use as paint, and I needed a lot of it. This is how I made it.

A number of the period manuals describe the making of powdered (sometimes called pan or shell) gold by grinding it in a mortar with salt and honey, somewhat surprisingly I decided not to use that method for my own uses. I'm not entirely certain why. Instead I went with a method that I have read about on various websites pertaining to Orthodox iconography painting.

Most of the time I use gum arabic in dry powder form, just adding a little to my dry pigment as I begin the grinding process. For this method of making pan gold I needed a liquid, so my first step was to make a high-ratio gum Arabic solution.

A quick search of the internet bought me to the following instructions:

"To prepare the gum arabic-water solution you will need approximately one part of water to an equal amount in volume of gum arabic. The actual proportions here is not critical, but what is vital is that the consistency of the gum-water solution should be like thick honey. In a double boiler, heat the water and stir in the gum arabic. Powdered gum takes less time to dissolve then lumps, but complete dissolution still requires about two to three days. After the solution cools, cover and leave it until the solution is clear and the gum completely dissolved. Strain the gum solution through cheesecloth into a clean jar. Keep refrigerated when not in use for it spoils easily. Never heat this solution over a direct flame or heating element, for it will scorch."

Unfortunately I didn't make a note of the source (if anyone knows the source please let me know so that I can give due credit), but following these instructions I set about making my own.

Supplies for making a high-ratio
gum arabic solution.
Firstly, gather supplies - distilled water, gum arabic powder, a measuring cup, a saucepan, a cup (or bowl if you prefer), and a stirring device.

Fill the saucepan with regular tap water and place into this the cup/bowl, essentially creating a double-boiler. Measure out a quantity of the distilled water, in this case I measured out a 1/2-cup, and pour it into the cup/bowl. Turn on the stove and bring the water in the saucepan to a boil, which will in turn gently heat the water in the cup/bowl.

Dissolving powdered gum arabic
using a double-boiler method.
While this is happening, measure out the same quantity of gum arabic powder (1/2-cup). Once the distilled water is warm, start adding the powder one spoon at a time and mix well to dissolve. Eventually the top will get frothy and it will thicken to the consistency of honey.

Once you're happy with the consistency, pull the cup/bowl from the saucepan, cover (I used a small plastic sandwich bag) and set aside to cool down. At this point it looks very creamy-white. Once it's completely cool, place it in the fridge.

After a couple of days the powder will have dissolved further and have turned a clearer amber colour, like honey. Mine still has what looks like froth on the surface, I'm assuming that this might be undissolved powder but I'm not completely sure.

Straining gum arabicsolution through
a cloth to remove any parti
The next thing you want to do will be to strain it through a cloth to prevent any particulates being in your finished solution. I cut up a pair of stockings (art before beauty!) to use as a filter for this and let the solution drain into a Mason jar.

Grinding the Gold into Pigment
Before you begin, find a comfortable spot to sit with a solid surface in front of you. Next cue up a movie to watch to keep you occupied while you do this because it is BORING...

You will need a shallow dish of some sort. I have a set of porcelain dishes I got from an art supply store, in reality you could just use a saucer from the cupboard (ProTip: Goodwill is a fantastic place to shop for such things).

First, add a glob of the gum arabic solution to the clean dish, about the size of a US Quarter (25c). Onto this place a leaf of gold, the same as you would use for gilding (in my case 23k gold from John Neal Bookseller). With the pad of your index or middle finger tap down on the gold a few times until it disintegrates into the gum solution. Add another sheet of gold leaf and repeat the above process until you've used about 10 sheets. You may find that you have to add a little more gum arabic solution if things get to dry.

You should have something that looks a little like the picture to the left. Now, add a couple of drops of distilled water to moisten it a little. You're now going to sit there for an hour or so, grinding the gold solution with your finger-pad.




The dish of gold will start to look like this. Continue rubbing (grinding) the gold particles to make them as small as possible. Once you feel that you been grinding for long enough, do it some more.





Finally, add enough distilled water to your dish so that it covers the gold and creates a small lake. Swirl the water around just a little, "washing" the gold, not to much though as you don't want to remove to much of the gum arabic, then let it sit. Preferably covered, and preferably overnight. By doing this you're allowing the gold particles to completely settle on the bottom of the dish since they are heavier than the water. The water will appear clear. Use an eyedropper (available from a local pharmacy) to carefully remove as much of the water as you can, you won't get all of it. Let the remaining water evaporate.

Congratulations, you now have a gold paint that you can use with a brush, pen or quill. Reconstitute with a little water and use in a similar manner to gouache or watercolour. I found that it has a fairly "gritty" consistency and I'm currently unsure if this is what you get since it's a metal or if I just didn't grind the particles small enough during preparation.

In the picture below you will notice a screw-top glass jar, this is dedicated rinse water for my brush. It allows me to trap any gold from the brush so that it can be re-prepared with my next batch of gold powder, thus not wasting any. For the same reason, when gilding I empty any random scraps into this jar.

Pan / powdered /shell gold for use with a brush or pen.


Sources:
CHOWDRY, Anita. The Alchemy of Pure Gold Pigment. 2011. Anita Chowdry. Web. September 2012. < http://anitachowdry.wordpress.com/2011/05/16/the-alchemy-of-pure-gold-pigment/ >

Author Unknown. The Technique of Shell Gold Painting. Natural Pigments. 2013. Web. July 2013. < http://www.naturalpigments.com/art-supply-education/cat/art-brush-info/post/technique-shell-gold-painting/ >

PORTER, Betsy. Making and Using Shell Gold. Art and Iconography. Web. January 2013. < http://www.betsyporter.com/shell_gold.html >

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