Indigo Vat Diagnosis: Vat Color, Flower, and pH

Q: The color of my vat before stirring looks bluish-gray-brown. There is a shimmery copper color on the surface of the vat, but no flower. When I take a pH reading the strip says that the liquid is higher than pH 11. Should I add more iron and lime even though the pH is so high?

A: The vat color can range and still be within working order, so first things first, I’d recommend stirring the vat thoroughly for about 30 seconds to get all the sediment up and moving so you can see what color the SEDIMENT is. If it is green/yellow, the flower will reform and you’ll be good to dye in an hour or so after the sediment settles back out. If the sediment is blue green or green grey, I’d recommend ‘sharpening’ with another 50g iron and 75g lime.

In the Ferrous vat, the pH is not particularly relevant - if it isn’t working, the answer is often ‘just add more iron and lime’.

To do that, decant as much of the vat liquid as possible (into some large stock pot) and heat that up to a simmer then add those ingredients.

Recombine everything, stir it all up so it’s properly mixed, then let it settle.

Always wait AT LEAST an hour (three is better) after stirring to dye to let all the sediment settle. The chalky green/gray/blue color on the fabrics comes from contact with the sediment. It needs to be blasted (hose) and/or washed off the fabric with soapy water (bar soap is best) before trying to dye again. The blue should ‘clean up’.