I am so ashamed, I was searching in the code, not in Unity.
I changed the shader in the material (from transparent/diffuse to Spine/Skeleton), and it works.
I can't thank you enough !!

I really don't know what you are talking about, I am so sorry. I also see now, that the title contains the tk2d package, but I don't use it (juste spine-csharp and spine-unity). Do I have to use it ? (if yes, I have some trouble to made unity works with it because spine-unity contains the same class as it, and juste with spine-tk2d it doesn't compile). Thanks for your time.

For an animation, every slot has a new color.
When I played this animation in Spine, the color appears correctly (on the character and in the Draw Order tree).

This color is in the .json file ({"Crete":{"color":[{"time":0,"color":"ffffffff"},{"time":0.0333,"color":"ff8e8aff"},...). But when the animation is played in unity (via skeleton.state.SetAnimation()), the color doesn't appear (with or without the code above).

Thank you for taking the time to help me

Hello,
Sorry to dig this problem, but I don't think this is implemented yet and I tried the code above. It works well in the SpineBoy example but not with an homemade animation, and I really don't understand why. Do you have an idea why or an advice about where I can search ?

Thanks,