I started with this piece of cloth which had several layers of dye and the piece was quite dark.
I cut of strip of fabric, folded it horizontally and then concertinered the fabric and clamped the square of perspex on it.
The shibori technique always creates different effects depending on where the fabric is in relation to the resist and the liquid solution. However, I may have got more even results if I had left it in the solution longer.
In another experiment I screwed up some of the fabric into a ball and held it together with elastic bands.
This time I left it in for about an hour and it is surprising just how much of the original colours and patterns are preserved. The thin lines of colour are where the elastic band created a resist. Is it just me or can anyone else see flowers in the piece?
My final experiment was to place a lose piece of the fabric in the discharge solution. In fact I did it twice leaving it in for 2-3 hours but it didn't seem to make much difference the second time around. It seems that once it's done it's stuff, it's done it's stuff.
You can actually see the original layers of print before the grids were added. Then there was the experiment with the commercial black fabric.
Again, the crispness of the square varied depending on where the fabric was in the pile.
If you would like to experiment with this method of shibori or like me, you are looking to remove your mistakes then you can get Thiox (also called Spectralite) from George Weil. I used 2 tsps of Thiox, 2tsps of soda ash and enough steaming hot water to cover the fabric.
Given the darkness of both fabrics it did a good job of removing the colour. The effectiveness of the discharge does seem to depend on the colour and depth of colour on the original fabric. In my lake piece there were large areas that discharged completely back to white but other areas were left a mustardy yellow. If you try this out, I hope that you get some interesting results.