Mixing liquid clear (paint retardant) and regular paint for the background?

I want to paint the background of a canvas a solid dark blue but mixed with Liquid Clear. Should I put the liquid clear first and then the paint thinking they will mix together or should i mix them together before they go on canvas? How much Liquid Clear goes on canvas because I heard not too much but that's kinda vague. Does anyone know?Mixing liquid clear (paint retardant) and regular paint for the background?
The retardant usually comes with instructions in the back. But what I do is mix them before you paint... like you do when you mix paint. I do 1/4 part retardant 1 part acrylic approx. I eyeball it.


Here's are some instructions I found:


Mix the additive to the paint when on the palette to slow the skinning-over of paint and increase blending time. You shouldn't add more than 25% and there is no binder and it can weaken the stability of the paint film when too much is added.





http://www.liquitex.com/Products/effects鈥?/a>





I hope this helps you. Take care.