How to fix acrylic paint on leather
How to use acrylic paint and marker on leather?
The surface should be properly degreased before use, e.g. wiped with rubbing alcohol, but be careful of washing the paint off the leather when degreasing. Apply the markers as you are used to. One coat is sufficient for most surfaces.
Fixation
No further fixation is needed on the leather due to the porous surface. If you would like better durability, you can fix the image itself with a water-based acrylic clear varnish according to the nature of the surface (glossy/matt).