Finishing and Installing
Let your piece dry. In warm sunlight, most crack fillers will dry sufficiently in eight hours; in the shade or indoors, it could take up to twenty-four hours. When you think it is safe to handle your piece, detach it from the board. The side that has been facing the board is the top of your mosaic. Trim the tarpaper on the top side so that it is a half-inch bigger than the tar-coated tarpaper on the bottom side. The layer of tarpaper on top of your piece will remain until it is washed or worn away.
Prepare the bottom surface of your piece. Different tar products dry to different consistencies. If your tar has dried like tire rubber—flexible, yet dry to the touch—use a paper towel to spread a very thin layer of fresh tar to the bottom side. The goal here is to create a sticky surface, not to make a layer of wet tar! If your tar has dried to be flexible and sticky, it is not necessary to add fresh tar.
Find a spot. Asphalt crack filler sticks only to asphalt such as is used to make roads, sidewalks, and paths. It does not work on concrete, brick, or cobblestone. Find a high-visibility location. We highly recommend crosswalks, as your piece is probably scaled for pedestrian viewing: pedestrians will be able to enjoy your work as they cross the road, and the passing cars will help mash the piece into the asphalt. Also, in their capacity as dumb and dangerous moving objects, cars will faithfully deter someone from kneeling down to pick at your piece. Yes, just this once, the cars are working for you!
Don’t let your masterpiece be covered up in the prime of its life just because the road needed repair. Your tile can last for ten years, possibly longer than its asphalt host. Apply your piece on the freshest asphalt you can find that is also a good location. Also, new asphalt is softer and stickier, and thus more receptive to your decorations.
Install your artwork. You should install your designs during warm weather, when the asphalt is warm, soft, and dry. If the forecast calls for significant rains in the next few days, wait until they have passed. Bring a small brush to remove sand or debris from the road. Place your piece by simply setting it down, tar side to the road. Now walk, skip, jump, and run all over it to make sure it is firmly planted. The top layer of tarpaper will serve to camouflage and stabilize your piece for the first few weeks, when it is most vulnerable, while it begins to join with the road. Eventually, the top layer will wear through or wash away, unveiling your masterpiece.