Saturday, 4 July 2009

A return to the subject of Washfastness

Before Woolfest I was doing some washfastness testing of my yarns, I do these tests at random times and on random yarns so I get an idea of how good (or bad) the dyes I'm using are, and my standards of mordanting and dyeing of course.

My method is following the recommendations in Gill Dalby's book Natural dyes fast or fugitive (a very good book and one that I think doesn't get enough praise, it's small and reasonably priced and chock full of really sound information!) The tests are not totally scientific of course - I don't have access to full laboratories and testing equipment, but I make the best use of what I have.

The yarns are stitched into mordanted cotton parcels (I reckon that if there is colour leaching then the mordanted cotton will take up the dye and show staining more clearly than unmordanted) I use my washing machine on the whites wash cycle and a temperature of 60 degrees (not very environmentally friendly, but it is for a specific purpose and only at random times not every week or day) full spin and Bob's your uncle! The detergent I used for these samples was Amway SA8 colour, a powder detergent that I have used for many years, originally I bought it because it was great for septic tanks, it isn't actually organically certified, but is certainly more environment concious that most. I also have Ecover non Bio in the laundry room. I don't add fabric softeners in the laundry but I do always give my wools a final rinse of Eucalan when I've finished dyeing - it's a fabric conditioner and moth repellant and I like it lots!

This sample is wool, it's not the clearest of images and you can tell that the wool hasn't liked the boil wash but there is no transfer of colour at all onto the cotton, the threads on the right are originals and the felted blobs are the ones that have been washed. There is barely any difference in the colours between the originals and the blobs.
The dyes used here were indigo, persian berry and persian berry overdyed with indigo for the green, the yarn is my Welsh wool, it's a 2 ply yarn but knits up as a four ply and is fab for socks because it's so hardwearing (felts well too!!!)

The next samples were some linen yarns. The colour that you can see on the cotton is actually fibres that have rubbed off the linen, not colour transfer, not sure whether the photo is clear enough for you to make that out - but "in the flesh" it is obvious! Here the dyes used were madder, cochineal and logwood, again there is virtually no difference between the original colour and the washed. There are different thicknesses of thread some 8/2, 16/2 and 28/2. It's the 8/2 dyed with cochineal that has "rubbed" off onto the cotton, the others have a much higher twist to them, so I guess that's what's helped there.
I've given information about the detergents I use because it's another thing that can affect the dye colours - if I used one that was more alkaline I could find that the colours actually changed in the wash, the cochineals would go more purple for example, yet another thing to watch out for!


Dorothy said...

Thanks for writing about this. I haven't done washfast tests before now, I will be interested to try it out with my dyed yarns.

I only bought Gill Dalby's book a few months ago and discovered I'd been missing out on far more than I imagined could be fitted into one small booklet. Just shows how true it is that "you can't judge a book by the cover".

Helen said...

Hi Debbie Those wash fastness test are fascinating and very reassuring too.
You and I plug away at promoting Gill Dalby's book and I glad to find that Dorothy has joined the fan club!