Thoroughly mix the grout with water. Use approximately one gallon of water per 80 lbs of mortar. The thickness or consistency of the mortar is important. It should be able to flow through the bag easily, but stay in the joint when applying. A good test is to stick your hand in the bucket and squeeze the mortar through your fingers; you should be able to turn your hand over and the mortar should not drop off. When mixing a mortar dye with the mortar, do not use more than ½ the box of dye for every 80 lbs. of mortar. Also, be sure to mix the dye and mortar in a dry state.
Fill the baker’s bag with the mortar (make sure the metal tip is in the bag) and while holding the bag at a 45 degree angle, squeeze the bag so the mortar will flow out of the tip. Be careful not to get any mortar on the face of the brick. If you don’t wipe it off immediately, wait until it turns stiff then scrape it off with a putty knife. After the mortar is in the wall it will start to set up.
When you see the moisture darkening the edge of the brick around the mortar and the mortar becomes crumbly to the touch, start to strike the vertical joints then come back and strike the horizontal joints. Wait until the mortar becomes hard, and then brush with a soft bristle brush.