This past weekend I got to try out my new iron dye pot! It is an incredible piece which is not only functional but so beautiful and based on an extant piece as well. It was made by Sir Edward the Red. Cenred forged a little metal ring to go around the handle so we would be easily and unobtrusively able to differentiate between the dye pot and any cooking pots which might be of similar construction. Apparently my idea to put a little piece of dyed yarn on the dyepot handle didn't go over well with the blacksmiths!
I used the dyepot twice. I've certainly used iron as a mordant before but never used whatever free iron might be absorbed just from a pot. I'd read several accounts of varying degrees of success or suitability but not enough to formulate any pre-conceived ideas. The fibre was wool yarn, pre-mordanted with Alum. The first dye was Sorrel and Dock seeds. The dye liquor itself was made up in a Stainless steel pot and transferred to the iron pot. The dye struck quickly and depth of colour depended on length of time in the vat, giving a range of colours from yellow to dark olive green.
The second dye vat was done by cooking crab apple leaves in the iron pot itself. The dye started off a pale "apple" green and got deeper as the dye liquor cooked over the fire. When I poured out the last of the dye, it was a deep, dark green. There was less variation of the colours with the apple leaves though, probably due to starting off with the iron pot. The crab apple, iron green colour is awfully pretty though. I ended up dumping a whole bunch of sample skeins into the dyepot in order to have enough of the green yarn to do a project with!
I was talking with Foote the potter about a celandine glaze he uses. The greens were in the same colour range of the Sorrel and Dock seeds with iron colour. It turns out that the glaze has iron in it. The percentage of iron used in the glaze is exactly the same as what I would use when mordanting with iron in a controlled manner. I'm pretty certain that using an iron pot is a rather uncontrolled use of iron mordant :) but in a stainless steel pot it is entirely controllable.