Here is the color chart for Jacquard's acid dyes: http://www.jacquardproducts.com/products/dyes/aciddye/colors.php

It sounds like your blue dye was not made with a stable pigment, but a combination of different colors. You shouldn't have that problem with browns, but contact Jacquard to be sure that you've picked good colors.

I used three browns and a sponge to do mine. Start with the lightest color, and work to the darkest color. I have had no fading at all, but what I have had is the nylon turning more amber, which makes the lightest of my color darker, and lessens the contrast, so keep that in mind.

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