2 Using palette knives
Palette knives aren’t just for mixing paint. In fact, you’ll see some knives marketed as ‘painting knives’. Really, just use whatever gets the job done. I’ve used large, plastic putty trowels for creating rocky textures in some larger paintings.
A generous amount of paint applied delicately with a knife. Thick paint applied with a knife by pressing straight down and lifting straight up. Paint scraped across the canvas. Notice how it describes the texture underneath. In this detail from a Bouguereau painting, you can see how he created a rocky dirt effect by knifing on paint.