Drawing render target over texture in material

Hi, I’m trying to display blood on object which are hitten by particle collisions, it is working quite nicely, but I don’t understand how to solve my material problem.
I’m using a render target with a white clear color, the problem being that it produce an overbright blood texture on the object, probably because of the white color clean right ?
Also another question, it is possible to include a normal map to the return of the render target, and some metallic / smothness etc… values ? So it lerp nicely between normal texture properties and the blood layer one ?

Object Material :


Blood effect which is overbright :
image
Brush Material :

Thanks, have a nice day !