These notes appear originally on the Yahoo Group 'Natural Dyes' and have been reproduced with the kind permission of the author, Dick Huset.
"Three years ago after a trip up to the arctic where the big lichen 'ears' have been an emergency food source for eons, I experimented back at home to add new color to my wife's yarn palette. Started with Castleman's book and cudbear references. As a biochemist and experimentalist, here's what I learned, and this may well help tune up the color flow.
Lichen contain the orchil dye precursors tightly bound inside cellulose cell walls. At least as tough as wood bark. The Castleman work results in digesting the cell walls in a fermentation process. So, ammonia is used here to macerate, soften, digest the material. It is not just a source of alkaline pH change as we use it in other dye work. Three other factors speed the digestion: warmth, moisture, and particle size.
So, I found the best and fastest and most complete use of the lichen to begin with blenderizing, pulverizing the lichens, adding the ammonia/water mix until it is as thin as pancake batter, then sealing into ziplocks. Throw into warm sunshine.
Daily mushing up the mix is done by squeezing the bag and turning it in the sun. Maceration is fast and uses up ammonia, so I add a couple spoonfuls by day 7 or so. After that I know that orchil is leaving the broken cells, so I start opening the zip daily or better to bring in the oxygen needed to 'develop the color'. Oxygen was not really crucial to the first digestion days, but WOW - type color happens when the oxygen hits the dyestuff.
Just a bit later I dump the bags of lichen mush into water in jars with minor amounts of ammonia. If you are into early period materials, you would not throw the mush into water, but knead in chalk dust until purple balls were formed, then dry these over a smudgy fire, and store on a shelf or sell to neighbors. These were cudbear dyeballs, and stored up the color for the future..
The reason I chose the early zip-bag process was to replicate Castleman's little glass basins - get more sun and warmth to the mush than would happen in a big water bath.
Hope that helps - you can see that not all chemistry types feel obligated to be numbers oriented. I've done most of this with only intuited measurements. And my purples and pinks and mauves are pleasing but not reproducible."