Back in August I posted about my process for making sure my hand dyed fabrics are colorfast. Since then I have done a little more testing and wanted to share the results.
Briefly, my process involves soaking the fabrics overnight in hot water with Synthrapol (or other detergent) instead of repeated wash and rinse cycles. My experience tells me that the long exposure to water is better at leaching out all of the excess dyes than repreated washign and rinsing.
In that post I talked about using boiling water. I still believe that boiling water is best but I wanted to exxperiment with very hot tap water. Now my hot water heater is set at about 140F. That is a level that requires me to sign a release statement for my plumber before he will set it that high. It's hot enough that we can scald ourselves with water from the kitchen sink. So, I believe that hot water is still key to this process.
But I wanted to test the time element.
I did this test in several dye batches but these two photos are representative of all of them and here's what I did.
- I rinse the newly dyed fabrics to remove the soda ash and I put the fabrics in a big basin of cold water while I rinse out the rest of the fabric.
- Drain the rinsed fabrics, add Synthrapol (or other detergent) and fill the basin with very hot water. I make sure there's lots of water in relation to the fabric. I want the fabric to get easily exposed to water.
- I agitated the fabric in the water (wearing double gloves for insulation) for about 15 minutes to mimic the time in a washing machine and then took about 1/2 cup of the water for a sample.
- I covered the fabric with weights 9as in the last post) to make sure all the fabric is under water.
- I took more 1/2 cup water samples at 3 hours and at 12 hours.
After I had all 3 water samples I stirred them to make sure that the dye molecues were dispersed in the dye and then poured about 1/4 cup of each on a folded paper towel. I let these dry so I could see how much dye had released from the fabrics at each stage. My goal was to determine how much time mattered in the soaking process.
You can see that there wasn't a lot of dye release at 15 minutes. There was some and this is about what I'd expect after a cycle through the washing machine. At 3 hours most of the excess dye has released but you can see that there is a little more after 12 hours. (12 hours isn't magical, it's just overnight for me based on my dye routine.) Can you see that the 12 hour sample is brighter? I think that's the turquoise taking it's sweet time to decide if it's staying or going.
This batch of fabrics had more reds than blues. There's not a great deal of different between the 3 and 12 hour samples but you can see more white areas on the 3 hour sample. That tells me that there is some additional dye release at 12 hours.
In all cases, the water is very dark after 12 hours and that may worry some people. As long as all of the fabric is submerged under water AND you have detergent in the water (I use about 1/8 - 1/4 cup for about 10 yards of fabric), the dyes will not reattach to other fabrics. I rinse bright yellow and pastels with every other color and have never had a problem.
Someone tried this method on a finished quilt recently where hand dyed fabrics (not mine) bled onto white fabric after the quilt was custom quilted. She did this process and got all of the excess dye out of the quilt. It will work on commercial fabrics too.
There you are. I am finally done with this little process! I will not bore you with it again but you can always find the information in my tutorials tab at the top of the page.

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