Sea Green and Sapphire

A blog about a love of colour, addiction to fabrics and joy of crafting…


Rosy Reds from Surprise Webcap Mushrooms

Finland, my home country, is a land mostly covered with forests and lakes, and in the late summer and autumn those forests are full of berries and mushrooms, so it is not surprising that foraging is deeply embedded in the Finnish genes, and berry picking and mushroom hunting are pretty much a national hobby at the autumn time. Although I have been happily settled here in the UK for a pretty long time, at this time of the year I always miss the Finnish forests and wish I could go there, pick wild berries and enjoy the wind in the trees and the damp mossy smell of an autumn forest.

And this year the urge to go foraging is even stronger than usual – I have just had my first go at mushroom dyeing, with the wonderfully named “Surprise Webcap” (Cortinarious semisanguineus, verihelttaseitikki in Finnish) and I managed to get the most beautiful rosy red colour from it. It’s by far my favourite red that I have ever managed create by dyeing so obviously now I just want to go and pick as many of these little mushrooms as I can possibly find.

Fibres dyed with cortinarius semisanguineus

Wool and silk dyed with Surprise Webcap, Cortinarious semisanguineus (the small skeins at the front are silk, the rest is wool)

Well unfortunately I can’t do that, at least not this year, but luckily I have a few mushroom agents (=my dad and my sister) scouting in the forests of Finland who have promised to be on the look out for some dyeing mushrooms for me. We are armed with a new mushroom dyeing book – Sienivärjäys by Anna-Karoliina Tetri, which is the first ever Finnish language mushroom dyeing book published (until now Finnish dyers have had to rely on Swedish sources). It’s an excellent book, I would warmly recommend it but I know the Finnish language might be a bit of a barrier for most of you.

As with dye plants, there are many mushrooms that will give your various shades of yellow, orange, fawn and brown. Beautiful as those colours are, you can easily get these colours from many plants, so dyers will get mostly excited about the rarer colours of reds, blues and even purples. The blues you get from mushrooms look particularly beautiful, some of them are more greeny blue, others bluey grey, all my favourite colours.

But on this occasion, I focused on the colour red as I had bought,  from Anna-Karoliina Tetri’s shop, some dried surprise webcap mushrooms.

yarn dyed with cortinarious semisanguineus (

Anticlockwise from the front (alum, alum+iron, copper+iron, copper)

I poured boiling water over the dried mushrooms, added some washing soda to the liquid to help the dye extraction process, a tip from Leena Riihelä of the Riihivilla blog (always a great resource on natural dyeing, and,  being a fellow Finn, she writes a lot about mushroom dyeing too). The stems of this mushroom give yellow colour and the cap deep reds, but my dried mushrooms had been dried whole and I didn’t bother separating the stems and the caps so it all went into the same pot. I let them soak properly for about a week, then simmered the pot for an hour, strained away all the bits and then was ready to go.

Finnsheep top dyed with cortinarius semisanguineus

I love the rosy red colour this mushroom gives on alum mordanted wool

silk didn't absorb the colour quite as strongly as wool so most of my silk skeins look quite pink. The copper mordanted silk  looked more like grey, so it's not really a combination I will try and repeat in the future.

silk didn’t absorb the colour quite as strongly as wool so most of my silk skeins look quite pink. The copper mordanted silk looked more like grey than red.
From the bottom: alum, alum+iron, copper, copper+iron and then above these, the same combinations again in a thicker yarn.

A ratio of 2 parts of dried surprise webcap to 3 parts of alum mordanted wool will give you a nice rosy red with a slightly brownish hint. Acid modification washes out the colour a little bit but an alkaline bath intensifies it. Wool mordanted with copper produced more brown shades with a hint of purple in them.

Dyes samples Cortinarius semisanguineus

Alum on wool gives you the stronger reds, copper slightly duller shades. The colours were much less strong on silk, more pink than proper red (the bottom 4 yarn samples on the right)

After my first dyeing session I noticed there was a lot of dye left in the pot, so I kept using the exhaust baths over and over again, getting increasingly light peachy pinks until after the 5th go, the yarn was barely off-white and so I declared the dye bath exhausted.

It took about 5 dyeing sessions to exhaust the dye bath

It took about 5 dyeing sessions to exhaust the dye bath

I had simmered my alum and copper mordanted yarns in separate pots to avoid cross-contamination. As I decided not to use any more copper-mordanted wool after the first bath, I chucked some alum-mordanted wool into the pot that had previously been used for copper-mordanted wool. And this was a happy serendipitous thing to do, because I discovered that this way, the reds I produced had a much bluer undertone that the “non-contaminated” alum yarns. I don’t often use copper as a modifier (to reduce the amount of liquids containing copper I am having to find a way to dispose of) but in this case, just by accident, I discovered a nice colour that I may well want to recreate in the future.

yarn dyed in surprise webcap exhaust baths

The grey yarn at the top left is copper mordanted, the yarns on the right are alum-mordanted yarns dyed in a dye bath that had previously contained copper mordanted yarn (the middle yarns are alum only)

One thing I will want to try in the future is modifying dark red alum-mordanted wool with copper, just to see what that blue/purple shift from copper would look like on darker red yarn. Luckily, I have one more 50g bag of this mushroom left so I can have another go soon.

And, my trusted mushroom agent has already sent an interesting looking parcel containing various little bags of dried dye mushrooms so I will be able to continue my experiments a bit longer. Mushrooms also keep popping up around here at the moment, so I may need to do some research on the dyeing potential of mushrooms growing around here.