community of dyers

The mixture of rust orange (Procion brown MX-GRN) plus cerulean blue (Procion blue MX-G) doesn't have enough yellow in it to make the mint green in your color swatch. I think you could get very close to that color swatch by mixing lemon yellow (Procion yellow MX-8G) with cerulean. Perfection would require a mix of cerulean, turquoise, and lemon yellow. I strongly advise spending some time playing with Olli Niemitalo's Dye Mixer Applet.

Cerulean blue responds well to chlorine bleach (the stuff whose active ingredient is hypochlorite), bleaching out nearly to white. I have no idea how well brown MX-GRN will do, though, whether it will bleach out or turn some weird color. Cerulean blue doesn't do as well with color remover (based on sodium dithionite a.k.a. sodium hydrosulfite).

Oh, another thing about rust orange: many dye suppliers have replaced the pure color with a mixture of more readily available Procion dyes; no idea whether this is true for your supplier (if it's not, we need to know about it) or what would be in the mix.

If that were my project, I would try overdyeing the colored part of it with yellow MX-8G to make it greener. You might prefer to try bleach or color remover first, though. You can always overdye after doing so.

Who is your supplier? George Weil's lemon yellow is a slightly warmer yellow, Procion Yellow MX-4G, but they also sell Jacquard Products' lemon yellow, which is yellow MX-8G.

Is your rust orange George Weil's brand or Jacquard Products'? If it's the former, there's a very small test I'd like to ask you to do, if you will, to see whether it's a mixture or a single pure color. I already know that Jacquard Products is now selling a mixture under that name.

-Paula