Experiments with silk part 2: Washing and dyeing

Monday, March 21, 2016

After my initial experiment with washing silk, I decided to buy a yard of the dupioni and give it a more thorough test. While I was pleased with the overall result on the 4" swatch, it was difficult really see the change in the hand of the fabric on such a tiny piece, and I needed to order organza and habotai for my couture dress project anyway. While I could have just bought coloured habotai I figured it'd be more fun to dye it myself, so I ordered some of Dharma's acid dye in the silver-grey colour when I ordered my silks. I decided to dye the dupioni at the same time, because I can at least use a yard of grey silk to make a skirt or something.

Anyways, back to the washing and draping. I took my yard of white dupioni and pinned and draped it around my dress form with folds somewhat similar to my wedding dress pattern. Ta-da! It almost looks like a dress already:

Unwashed dupioni pinned and draped
Unwashed dupioni close-up
Before washing, the fabric is fairly stiff, and the draped front section of the bodice is kind of bubbly and unflattering. I prefer how it falls after washing - it'll move with me rather than being a kind of exoskeleton.

Washed dupioni pinned and draped
Washed dupioni close-up
You can really see the difference at the sides of the skirt, where the unwashed fabric sticks out a lot more. I also didn't notice earlier, but the texture of the fabric has changed significantly. It is a lot smoother before washing, which admittedly does look nice, but I can't have both.

What about shrinkage? Turns out that Dharma cut me a rather generous "one yard", and my shrinkage was consistent with the test swatches.
One yard length before washing
One yard length after washing
On to the fun part! Now that I'd tested the draping behaviour of a whole yard of silk dupioni, it was time to dye it (along with my habotai), both to subject it to the most intense washing procedure ever, and to give me a more usable colour of fabric. The first step was weighing the silk and then washing with something to strip away any oils or sizing. I didn't have the recommended synthrapol, so I just used dish soap and very hot water. If it can handle this, it can handle anything!

1500 grams of silk getting a bath in the sink
I opted for the low end of the recommended intensity range, so I ended up using 22.5 g of dye powder for 1500 grams of silk, which is the combined weight of my 1.5 yards of habotai and 1 yard dupioni. The instructions stressed the importance of dissolving the dye thoroughly before adding the fabric, so I mixed it up with a cup of boiling water and let it sit for a while. This stuff did not want to dissolve in such a small quantity of water, but after about half an hour of sitting with occasional stirring, I decided it was as good as it was going to get. I strained it through a piece of organza to pick out any lumps:

My high-tech dye strainer 
In the end I had a pretty uniform cup of super-concentrated dye. Much to my surprise and delight, this did not get all over my kitchen - in fact, it only seemed to want to stick to its intended target, the silk.

The dye concentrate
As I was spending all this time dissolving the concentrated dye solution, my largest pot was slowly heating up on the stove. I think it holds something like 30 litres. The dye dissolved into the water really well, so I went ahead and added the silk. Apparently it's important that the silk be thoroughly wet before adding to the dye pot, and it should be brought up to temperature together. I think the water was around 130 F when I added the fabric (I actually had to put in some ice cubes because it fully boiled while I was futzing around with the concentrate).

This produces the most disgusting looking soup ever:

Yum
I basically stood over this pot and watched an entire episode of Supernatural while stirring and waiting for it to come up to temperature (185 F). It was really cool to watch the water clarify while the fabric sucked up the dye:

It's working!
When the water bath hit 185 F, I held the fabric to one side as well as I could and added about a cup of vinegar. I stirred this around and cooked it for another half hour, then pulled out the fabric and dumped it into a sink full of tepid water. The fabric took up the dye really well, leaving only a pale hue to the water bath:

This started as inky black!
Again, I was really impressed with how well the dye stuck to the fabric and only the fabric! I washed it again with dishsoap in warm water, and barely any dye ran out of it:

Washing the dyed fabric. That colour is stuck on really well!
To dry it out I strung up a clothesline in our hammock room/spare bedroom. I was so confident that the colour wouldn't drip off that I didn't even bother covering up the white duvet. At this point the fabric was quite a bit darker than I had anticipated, more of a dark plum than a silver grey:

Move over hammock, it's drying time.
 Since the dupioni has now been boiled for the better part of two hours and scrubbed twice with dish soap, I figured it's shrunk as much as it's going to. To my surprise, it only shrank an additional half inch. I wonder if Dharma sells their yardage in anticipation of shrinkage in the dying process, or if I just got lucky?

In the end, I have exactly one yard.
Just for fun, I went back to the dress form and draped the dress again, in grey this time. You can see how well the colour lightened up when it dried, and the silver grey description is pretty accurate. I don't think the hand has changed significantly compared to the single wash, but you can definitely tell I took the picture in daylight this time.

Washed, dyed, and draped dupioni
Close-up of bodice draping
In the end, I'm pretty confident in my decision to pre-wash my wedding dress fabrics. I'm also really excited at the possibilities opened up by this dying experience - it went way better than I expected, and now I want to make everything out of silk. 

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