Green from blue

Iris petals

There is a remarkable medieval green ink that is pretty easy to prepare – as long as you’ve got some blue iris flowers handy – and that is iris green. This color is one that has been associated with sap green, the classic watercolor made from buckthorn berries, but iris green may actually have preceded sap green in use. At some time iris green was even called sap green. It’s been written that it is essentially impossible to distinguish one from the other in old manuscripts; but the bright, delicate greens I’ve been able to get from iris flowers I prefer to the olive greens I’ve gotten from buckthorn.

As I’ve posted here, I am growing some heirloom iris plants in my garden plot, and after a year and a half of care they began to bloom this spring. My irises are more on the violet side of blue, but this doesn’t seem to make much difference. In fact, my irises have a lot more dye in them than the irises I bought at the nursery last year for my first test. There’s something to be said for growing heirlooms. Here’s the procedure:

Cooking iris petals

We’re making ink, so you want to make sure the dye is pretty concentrated in color. After chopping the iris petals into medium-sized pieces (Yes, you have to destroy the pretty flowers – I wish I could simply use the flowers after they have dried, but it just doesn’t work as well), split them into roughly equal parts. No need to be exact. Put one half into a small saucepan and cover them with distilled water. Steep or simmer them until most of the blue or violet color is gone from the petals, then strain them from the liquid, which will now be a pretty rose color. This should take a half an hour or so. Once you’ve strained the first batch of petals out, then add the other half of the petals to the bath and repeat the process. Splitting them up and adding them sequentially to the same small amount of water allows for a more concentrated color right off the bat.

Filtering the dye

Once you’re done with this, you should have a liquid that is a nice deep purple, deep enough so that you can’t see through it. You’ll want to filter it at this point to remove any petal debris, bugs, pollen etc. The setup I use is a really simple one: just a funnel (you can get these at Wal-Mart or any auto shop) and an ordinary basket coffee filter. I wet the coffee filter a bit before using it: already being wet, it doesn’t soak up as much of the dye. To collect the liquid I use a Mason jar, which will handle hot liquids pretty well – the last think you want is for your precious dye to crack the jar and spill all over the kitchen! – but even so, if I’m patient enough, I try to allow the liquid to cool a bit before pouring it in, cool enough to dip the tip of my finger into it.

Even with what is almost entirely liquid, the filter can get clogged and go slowly. Once it’s finished, you have your filtered dye. If all you want is a purple ink, then you can stop here; but the magic of iris flowers is their ability to make the medieval green. Purple can be had from many different natural sources.

Iris dye

To the right is the color of the dye as it is at this point. The next stage will be to add alum to it – the alum is what gives it its green color. Alum, or potash alum, is aluminum potassium sulfate, a crucial ingredient in dyeing and lake pigment production. It’s been used in dyeing and pigment making for – well, for quite a long time now. It’s also used to make pickles and maraschino cherries. Apparently you used to be able to get the stuff just about anywhere: the spice aisle, the pharmacy, etc. Perhaps if you live in a more rural part of the country you still can. I buy mine from an online dye supply shop. I’ll go over this stage in the next post.

Tags: historical color, ink, iris green, medieval art, natural organic, natural pigments