Some years ago I died the silk span on a Barnstormer to see how it would work, I used Rit brand dye, and mixed the dye in thinner, letting the dye settle, then shaking it many times to blend into the thinner.
  Then I mixed the thinner into clear dope, about 50/50 and doped the silk span, it turned out okay, but the dye faded in the sun light.
  Hope that this helps, and good luck..

And the fading problem is why folks have gone to other methods. Pete Peterson uses Kandy Koncentrates from House of Kolor. Cover the plane then mix them in your clear and start spraying. When you get the transparent color you want, stop. It doesn't fade and looks pretty slick.

But Higgins will fade too. The red and blue will be gone very quickly in the sun.

Has anyone tried aniline dye for coloring?  It's expensive, but a tiny bit goes a very long way!

Hi Brother Will,

Bob Bunt used aniline dye on the polyspan he covered his Frisky Pete with.

BIG Bear
RNMM/AMM

I have used analyn dye on my Frisky Pete and my Hobo (will be in the August 2012 Model Avation) with good results with no apparent fading.
I will try the House of Kolor Kandy Konscentrates in the future.

Will,

Try here: http://www.tcpglobal.com/hokpaint/hok-kandy-koncentrates.aspx

It's an additive you put in clear (lacquer in our case - or urethane is you are so inclined).

You could paint your sunglasses I guess...

Hi Brother Bill,
Did he have much sun exposure since?  How did/has it held up?  I love the stuff for guitar work, have threatened to use it for stunters but haven't yet.
Hey, on a more important note, how you healing, friend?

HI Brother Will,

(I mis-spelled Bob Hunt! LOL!!) anyway, I have not heard much after he built it and took it to VSC.........

Thanks for asking about the healing process, it is going VERY slowly......... but it will be ok in the end!

 BIG Bear
RNMM/AMM