Although I could see many blood splatter tutorials. I couldn't see any tutorials on this specific topic.
I have this white clothed wall:
I want a different blood splatter effect to stick on the wall in subsequent fashion after each character has entered.
I have the fake blood and want to do the designs myself on other white walls then paste them in, like an overlay.
The more actors that come in, the more blood designs are on the wall.
How do I achieve the blood on the walls from filming seperate blood designs? (or is there a better way?)
How do I deal with actors walking infront of the wall where I want the design to be?
As you can see from the picture i've had a real, on set, physical trial already, but unfortunately with the actors coming in at different times the effect doesn't stay as saturated for very long.
Shoot your actors on blue screen/ green screen, keep the wall a fully separate shoot, then combine the keyed actors with your filmed blood. If you are concerned about saturation, consider using something less watery and more intense. From deep blue glycerine ink (as used in roller pens) to fruit juice to some acrylic paint types there sure are enough options. Don't even concern yourself with the color, a simple hue shift can turn everything red. When keeping things separate, you should have no problems doing all the blood as a practical effect.