Brush: Stiff Bristle Brushes, round and square both work for various application areas.
Product: Works well with most popular brands of acrylic paints, better if the paint is not too thin and if it doesn't get rubbery and ball up in the brush as it dries, also better if the paint does not have a glossy element (The old brand Studio Stains were terrible to Dry brush with due to this.)
Supplies: Absorbent material like scratch paper, (Nothing with ink print that can be picked up in the brush, newspaper is notorious for this) Towel, tile or paper plate (Water - used only for clean up)
Piece: Especially suited for pieces with lots of texture, but can also be used on smooth areas to create a soft look when applied evenly. The basecoat should be darker than the color being used to Dry Brush over the top.
Prep: Base coat the area with a color that is darker than the desired outcome. Black is a typical color used as a base, or other dark colors like Doc Holliday's Real Brown, Steel Grey, Midnight Blue, Shadow green, etc. You can also basecoat a light or medium shade and then antique with a darker shade to achieve the depth in the cracks.
Method: Dip the end of a clean dry brush into paint that is lighter than the base coat and then pounce most of the color off on the scratch paper until the brush marks on the paper resemble "chicken scratch", very rough, very dry, no wet blobs. Swipe the brush back and forth against a textured area getting an all over fuzzy appearance keeping it even and consistent. Repeat this over an area several times, building layer upon layer until you achieve the coverage you desire. Maneuver the brush across the grain in a manner that keeps the bristles out of the crevices, allowing the darker base to stay dark. You can keep adding different color to your brush blending and highlighting. If you want to change to a clean color without this blending affect, you need to use a new dry brush, or clean your brush and completely dry it, working it against a towel until it is dry. This technique does not work with any added moisture in your brush.
Brush: Soft Bristle Taklon Brushes, square shaders regular length work best. (Short "Bright" Shaders are not optimal)
Product: Works with most popular acrylic brands, however works best with a thick rich bodied paint that stands up or "piles" on the tile when squeezed out, rather than a thinner paint that "pools" when squeezed onto the tile. My favorite Brand for Wet Brushing is Doc Holliday. The consistency is perfect and they have a nice range of rich, bold and bright colors. It's important to have paints that have rich deep shades, because light pastel shades can easily be achieved by adding white, but it's more difficult if not impossible to go the other direction without raw materials.
Supplies: Scratch paper to blend on (no transferable ink print), Paper towel (doubled and folded) to absorb moisture (Bounty works great), Water, tile
Prep: Same as above
Method: Prepare & load the brush: Dip the square shader in the water bowl, tap on bowl rim to shake off excess, gently and briefly, blot brush on towel to absorb initial excess water. Dip the end of the brush in the color, swipe back and forth the scratch paper to work into the brush, blot briefly on towel again. Repeat the paint and towel blot (do not add more water) 3 more times. Brush is now prepared. From this point on dip in paint, blend briefly on paper and go directly to the piece, holding brush at an angle dragging across detail. Color applies thickly and all at once as opposed to going on in layers. Maneuver the brush to avoid getting the tip of the brush direction in the cracks, keeping the darker basecoat showing through. You will learn to maneuver your brush so that you do not get blunt square brush tip marks from starting a full load of paint in the middle of an area, rather, start at the edges and drag to the middle. This takes a little practice, but the effects are amazing and well worth the time to learn. I will be positing some short "how to" videos as soon as my studio remodel is complete... getting very close! Feel free to ask questions if there is something you would like me to clarify.
Hope this helps you in your painting adventures!