They are another classic of the natural dye world. Buckthorn berries, Avignon berries, or best known as; Persian berries. Buckthorn shrubs are common in the east and have been cultivated in Europe since Roman times. In the United States some species of Rhamnus are considered invasive and they are being actively eradicated.
Our Persian berries are foraged from the wild in Europe and are organic. They undergo a special treatment with Co2 in a pressure chamber to make sure they are sterile, free of bugs and potential pests before being packed for the end user.
Persian berries are a substantive, and good lightfast yellow dye source. The active dye ingredient is Rhamnetin (Azaleatin) with the chemical formula C16H12O7. Some subspecies also contain other colourants such as kaempferol (R.cartharticus), quercetin, xanthorhamnin, and emodin. In history the active dye component was called Stil de grain yellow, or sap green.
Back in the days, buckthorn berries were used for their pigment in various ways; to make a green ink for use in medieval manuscripts., as a yellow wall colour in England (18th century), as a lake dye called Dutch Pink, and of course for shades of yellow and green on textiles. The boiled down Rhamnetin syrup would be stored in sheep’s bladders before getting used further.
Should we use the unripe berries or the ripe berries?
In the 16th century dye book The Plictho by Gioanventura Rosetti there are multiple recipes for using Persian berries. In recipe 105 it says;
Take little apples of buckthorn at the time of St Michael. the month of September. See that you take said little apples at midday and that it be not rainy weather and neither should it have been given frost.
This explains to us that we should use the mature berries for the dye. Another recipe for leather says;
To make green color on skins.
163. Measure the small apples of buckthorn of the month of september and which are about to ripen. Take the quantity you need and pestle them a little;e and put them in a small cauldron. Put into it as much white vinegar or strong wine that covers the said little apples and not more. Put in also a little Roche alum pestled. Allow to boil for the space of saying six paternosters and not more. Then take it from the fire and allow to cool. When you want to use it, dye it cold this way. (...) and you will see it become to the manner of a green grass.
One 'paternoster' takes me about 26 seconds to recite (yes, I timed it), so safe to say not to go over three minutes for this recipe.
To make green ink from Persian berries;
boil down 50 grams of berries and 200 ml water until it is very a very concentrated 100 ml. This will take some time. Strain the water through a cloth. Add one teaspoon of alum and a spoon of acetic acid for green ink. Add soda ash instead of acetic acid if you want yellow ink. You can add gom arabic solution if you want the ink to have a gloss.
To dye fabrics yellow with Persian berries simply add washed and scoured textiles to the dye stained dye bath. For dyeing textiles we use around 200% WOF berries. I soak them in warm water before extracting the dye in plenty of water brought to a boil. You can mordant your textiles with alum or copper sulfate for increased lightfastness. Dyeing the berries and the fabric together will get you many many blotches (from experience), so the straining should not be skipped!
To dye fabrics a greenish tint, add alum and two spoons of acetic acid to the strained dye bath. Persian berries dye wonderfully on protein and cellulose fabrics.