Mushrooms to Dye For

I thought I would share what I've learned so far while using our recent mushroom haul in some yarn dyeing experiments. 
First, I was asked for more information about this hat:

I knit this in Cascade 220, which I dyed with 2 different kinds of mushrooms.  Both the pale yellow main color and the chartreuse stripes were created from Boletus edulis, or Porcini.  One can achieve lighter or darker colors from the same dyebath, depending on the ratio of mushrooms to fiber.  Or, as I did in this case, by dyeing a second batch of yarn in an "afterbath" or previously used dyebath.  The taupe-like shade was created with a Hydnum imbricatum, commonly known as a Hawkwing mushroom.  I've been searching unsuccessfully for more Hawkwings ever since. 

When I made this hat, all I knew was that you prepared a dyebath by cooking all or part of the mushrooms, and that you could add alum as a mordant.  I was operating under the assumption that any mordant was better than none, in terms of achieving a more saturated color. 

My husband is waiting for me to knit this Klaus pattern from Cocoknits.  I already have a number of skeins of yarn dyed from Porcini, so now I need a contrast color.  So, after our last mushroom hunting trip, I decided to be more methodical.  I read more about the mordanting and dyeing process in The Rainbow Beneath My Feet:  A Mushroom Dyer's Field Guide.  This book gives recipes for various mordants including alum, chrome, tin, copper, and iron.  However, I've used only alum and iron.  I have gathered from reading other sources that many people have stopped using chrome, tin and copper because of their toxicity. 
I made two different dyebaths by cooking one pot of Boletus edulis, and one pot of the single woody mushroom I found.  I had high hopes for this second mushroom as it is commonly know as the "Dye Polypore".  I used three different yarns, prepared three ways:  no mordant, alum mordant, and iron mordant. 
Here are my results: 
(This blog post is starting to feel like science homework.)

Porcini Dyebath:

Dye Polypore Dyebath:

These photos did not capture the colors accurately but you get the idea.  While none of these colors fall into my favorites category, I am so happy that I went to all this trouble.  Now I know that alum brings out yellows, and iron enhances greens.  And sometimes no mordant at all is even better.  I still have one more shot at getting my hands on some Hawkwings this Fall.  If it works out I will use that to dye more yarn for Klaus.  If not I will use more Porcini with iron mordant to aim for that olive green pictured above.

Soon, back to sweater finishing...