Thursday, October 30, 2008

Woad colours

These pictures are from the student's science fair project on woad. This experiment was to test the effects of pH on the colour obtained from the woad vat. All were dyed in a reduction vat with the dye being reduced at different pH's.
Each silk sample was dipped for 15 minutes and oxidized for 15 minutes three times. All samples, except the green were rinsed in a weak vinegar solution after dyeing. All samples have been washed in detergent and water and rinsed in water again. No light fastness tests have been done.
Yellows, pinks and peaches can also be obtained from the woad leaves, after the indigo has been extracted. Pinks are obtained from an acidic vat and yellow after washing soda is added. The different pigments are soluable at different pHs.
Everyday woad yields more amazing discoveries. Yesterday the student extracted the DNA from fresh woad leaves. The DNA was blue rather than the usual muscus clear colour. We don't have an electron microscope in the kitchen laboratory so that was the end of the experiment. But rather exciting anyway.

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