Instructables

Step 2: Painting the joint color

Once you have your design masked, you can spray the joint color.  I used a light tan color with some darker tan accents.  Your joints can be whatever color you want them to be, just so they are a little different than your brick color.  Typically, joints are lighter than the bricks.

I gave the whole area a good coat with the light tan, and then went over it lightly with a darker tan.  The darker color has a texture so I rubbed it with my hand as well as a cloth rag to get it to smooth out a little.  If you barely press the nozzle on the darker color the paint will "sputter", this adds some nice texture almost like sand in the mortar.  Just try to avoid blobs and splotches in your paint.  If you mess up, just re-coat with your base color and try again.  Bricks and mortar are hardly ever perfect with solid single colors, so variety makes it better.