There are a whole lot of methods to brain tanning, most of which yield similar results. Mine is done kinda like Pappy's. The brains look somewhat akin to a strawberry milkshake while it's in the blender. I mix it with more water to thin it out. Just guessing, I probably use one pound of brains with a gallon or two of water. I pour the mix into a 5 gallon bucket, and then soak the hide for an hour or so. I used to always soak them over night, but that brain mixture gets pretty rank when you do that in the summer. Now, I soak for a shorter period of time, but I ring out the hide more often. The hides come out about the same, either way.
I do know some guys that like to slather the brains on fairly thick. I've never tried it that way.
Curtis