Favourite thing on a Friday - logwood purple

My favourite thing this Friday has to be logwood purple.  I have been dyeing with logwood this week.  The dye comes from a tropical tree, it arrives as fine chips of wood.  I extract the dye from the chips, strain off the chips and then dye the yarn.  It is a slow process.  However the colours are amazing.  You can get a dark purple:

Or paler shades of lavender:

The camera struggles to pick up purples accurately, the colours look more blue in the photos. 

This week I make a strong dye bath and dyed a batch of purple yarns.  The next day I wanted to use the same dye bath to get lavender shades.  I lifted the lid on the dye pan and saw the liquid was no longer a lovely purple .  The dye bath had turned a nasty browny yellow - arrrgh.  Since this has happened before I knew what to do.  It annoys me that books on natural dyeing do not always warn you this can happen.  Last time I dyed with logwood and got a ghastly colour I did some frantic internet research and discovered logwood is affected by the pH value of the water.  To get lovely purples you need an alkaline pH. 

I don't understand the science but somehow how my dye bath had changed pH and was now pH5, acidic.  I dissolved some washing soda in hot water and added it to the dye bath.  Instantly the water turned purple!  I put the yarn in the dye bath but I had to add more soda as the water started going yellow again.  It is better to add small amounts of soda and keep testing the pH value until it is correct.  Of course wool is not fond of an alkali solution so it is important not to let the dye bath become too alkali.  I find pH9 gives a good colour.

The yarns I have dyed this week will be on sale at The Big Knit Show this Sunday.  There are also some yarns dyed with logwood available in my shop.

Now do go and see what everyone else has chosen for their Favourite Thing on a Friday!