Achieving the Faux stone look is easy if you follow a few painting rules. Just like in painting the idea is to layer paint in thin washes using the fat over lean rule. This means that you have to start by applying thin washes and gradually build up towards the look that you are after.
My dollhouse has a lot of brown and blue grey tones so those were the colors I wanted to incorporate for the patio tiles. I am redoing a plastic dollhouse, but you can use this technique on card stock as well as other materials. Once you have the texture the application of paint is the same.
There are no straight lines in nature, but a series of colors that are close together giving the illusion of a straight line. Avoid the temptation to create lines. Let the colors do the work for you for a more realistic look.
You can use your fingers as well to rub the pastels in. However keep some of the pastel texture as well in random places - it just adds character.
Applying fixative will protect your work from getting soaked and warping. Since I am doing this technique over plastic I did not have to spray the fixative.
Gravity is your friend here. The water will take the watercolor and move it randomly around. If you want more color just keep dipping the brush into paint and reapply. If you over did it use your finger or a paper towel and dab the excess off. ( More in the video)
As you can seen it looks rather messy at this stage. However once the final coat of blue grey goes over the dry surface everything will come together rather convincingly.
This paint has a clear gel like consistency that adds a nice sheen to the rocky surface. Since the pigments are kind of floating in the gel, you can use this to your advantage. Where you only dip into the gel the paint applies like a varnish and lets the underlying colors show through. When you apply more of the actual paint it take on a darker grey blue tone making the darker areas look more like rocks.