wow... outstanding build Scott!
Luis... I haven't had that problem either.. wierd.. here is my cockpit I am working on at present for a F3F-2 at Pearl Harbor, the floor is done with W&N Paynes Grey with more areas to follow:
How much water are you using with the sludge wash? I thin mine to look like coffee... it's thin and flows but totally opaque.. I also use a flat brush to mic it rubbing it into the bottom of the pallete I use for my washes to make sure it is mixed good...
are you gloss clear coating first? I am sure you do, it's just a rhetorical question trying to figure out what is happening... (basically I was talking /typing/ to myself haha)
---edit--- you say when you mix your acrylic with water you see grains in the bottom? it may be the paints' fault then... with me the paint I put in the water is like a piece of axle grease until I use a flat brush to mix it then it dissolves entirely into the water....