There are several methods of washes or should I say applications.This method works for me and Im not implying its the only way, but I personaly love it.
I only use six colors, raw sienna, yellow oxide, burnt sienna and the3 darker colors, a hooker green, paynes grey and burnt umber. All tubes are acrylic paste concentrates from Walmart or art stores.
I use a wet 1 in brush with a very little amount of paint, perhaps tad of paint on three or five brissles of the very wet brush. Were not painting here, were washing. Water in a small bowl and a tad of paint on the rim, a hair drayer in one hand, brush in the other and this is a very quick process.
I use a hair dryer between coats as we dont want the coats blended togather, we want extreamely transparent colors to shine through each other in layers,(This is the Key, Many Thin Washes to highlight each other.)
The above are washes over a flat latex earth tone ( very very boring earth color) , note the different colors , a tad of hunter green in grassy areas, panes grey in granit rocky area and perhaps more yellow and browns in earthey areas. Thiss took about five minit to do. There is very little grass applied and the hunter green really makes it look naturaly blended.
I wanted a light color above to highlight another layout area, I used all colors repeatedy untill I got the tone I wanted. This wash was over a white gesso paint ( the same paint a artist prepares a canvas) and really looks like rock up close and personal. This method reall makes the colors look fantastic.
I will be back, need another pic
This area is also over gesso but the point I want to make is this. To get a more granit effect, (Greyer rocks) use the ligh