Orpiment is Lead Sulfide. It was used to make beautiful rich yellow gold colors. It is also deadly poison. I'm sure some monks had an idea one needed to be careful...it was no accident that only the scriptorium monks seemed to go a bit funny faster than everyone else in the monastery. But they probably had no idea what exactly was making them go off. Lead poisoning takes a while. And since we don't have records of monks becoming violently impatient or severely intellectually damaged, presumably they were more careful that we expect, if only not to waste some of these valuable ingredients.
I was willing to experiment with the real thing which you can get. But only in a premixed liquid form. Alas, all that was available were powers which I had no confidence I would be able to regularly handle safely. That would take
cleanroom care and I know I can't be bothered. If it was a liquid in a tube, I could easily segregate and dispose of brushes etc. But mixing lead sulfide dust? Nope.
What to do? I restricted this project to natural pigments, maybe not exactly the ones monks used, but things they could have used. And I don't want to cheat. I feel paper is a reasonable cheat, calves skins being hard to come by.
So read up on all the well known yellow pigments of the old masters.
Indian Yellow seemed nice. Ah, but it involved mango leaves and animal abuse. Really. It's pretty awful if this is accurate. There is a modern substitute which would do in a pinch, but I was unenthusiastic.
There are some bright ocher yellows, but lets not kid ourselves. Colored soil is not going to approach the vibrancy of orpiment. I'd rather use yellow.
That brings us to plants dyes, specifically laking plant dyes. I'll have a laking post soon(link). There were a couple of good subjects by color. Saffron was too expensive...any saffron I'm going to cook with!...but there was turmeric.
Turmeric makes a bright yellow, and there was plenty about because I use it for egg dying in the spring. So I laked it, just so I had something if nothing better came along.
Problem is turmeric is fugitive...it is not colorfast and fades rather noticeably after a year, in even indirect light. Next up: mullein.
Mullein makes a nice pastel yellow dye on cloth. So I wasn't to eager to waste my time laking it. The other problem with lakes is they are semi transparent, that is they have no coverage power. I was already figuring I'd use zinc as an undercoat. Then I read somewhere weld...the go to yellow dye of the middle ages...when laked and precipitated on chalk, could be as brilliant as orpiment.
That's when I decided, okay, okay, I'll buy weld seeds! Up until then I thought weld was over rated. Yellow dye plants are really easy to find. But weld is the most colorfast natural yellow. So fine, I would try laking weld on chalk.
But it would take a while to arrive and mullein was in the garden. I'd already done a lake of mullein. And I was shocked and pleased it was a much brighter yellow than it dyed fabric. So may as well try out the process before the weld arrived.
Laking on chalk is very similar to regular laking: instead of lye or soda ash, you add the chalk mixed in water, but in a slightly higher proportion. Instead of the alum and ash binding with pigment to make a colloidal fluid mass, the alum and pigment bind to the chalk and fall to the bottom...eventually.
WARNING: Do this over a sink. The container must be at least twice as large because the reaction, while not explosive, is vigorous. It foams up to twice its volume, before eventually calming down.
Once the mixture stops being a drama lama, it needs to be washed, much like extracted indigo(link). You cannot depend on filters to make your life easier, unless you have the finest top of the line chemical supplies. Really, once pigmented chalk is poured out to dry, it loses water pretty fast, unlike indigo which takes it's time.
This could work. Then the weld seeds arrived and I was so excited.
Turns out starting weld is bloody fiddly. If I had time and room in the garden, I could experiment. But I know I'm working with a hard deadline. I want to be painting and lettering by the end of summer and the seeds came in early July. They take two weeks to germinate. The prefer partial shade, though the need light to germinate. It's never easy, is it?
First three plants germinated adequately. Then, all but one died from too much sudden sunlight in their pots. The survivor was moved to a north window. It's hanging on gamely, but not large enough I feel safe putting it anywhere outside.
I start another pot. Two more germinate. It's looking good. Then, suddenly, at the end of the day, one just gives up an falls over. Cop on! This is a vigorous weed that grows throughout Eurasia!
There's nothing for it. I have to accept the weld might not come through in time. The survivors are still in pots, now outside on the back ...shaded.. porch. In the meantime I experimented with the other yellow herb on the property: tansy.
I grow tansy--along with mugwort, vervain, and feverfew... as a digestive bitter. And it's flowers are YELLOW. Oh boy, are they yellow. So trimming only flowers...no leaves need apply....I boiled them per the usual laking method, added alum, then the chalk...and forgot about the vigorous reaction.
It was very amusing. I was able to act fast, save all the mixture by quickly pouring things into larger containers.
Except for that bit of excitement, it was quite a success. Really, the color looks more gold and vibrant.
No idea about colorfastness. But by this time I just reminded myself: they probably kept the gospel book closed most of the time.
I will return to weld if it grows big enough, but I'm also ready to do without it if I must.
