Set in Stone “So you see, imagination needs moodling—long, inefficient, happy idling, dawdling and puttering.” —Brenda Ueland Gluing shards to concrete surfaces, statuary, and birdbaths is not much different from tiling a wooden surface. The biggest difference is the preparation, adhesive choice, and upkeep.

When gluing directly onto concrete there are a couple of things that you must do to assure your success.

Preparing Concrete Before Gluing

Tools and materials

1. Box of trisodium phosphate (TSP)
2. Concrete patch, if repairs are needed. This can be found in most home improvement stores.
3. Concrete sealer
4. Rubber gloves
5. Bucket
6. Wire brush
7. Foam paint brushes
8. Rags
9. Drop cloth or layers of newspaper

Directions

1. Mix the trisodium phosphate in a bucket according to the directions. TSP is a popular cleaner that helps ensure that the surface is free of dirt, grime, or grease. Objects glued to a clean concrete surface will have a much stronger hold.
2. Scrub the piece with a wire brush.
3. Let dry completely.
4. If you see cracks in the concrete that need to be repaired, fix them now with a concrete patch. Let dry.
5. Seal the concrete according to the instructions on the package of concrete sealer. Let dry.

Adhesives

Working with concrete means that you have to have the proper adhesives to assure that your finished project will withstand the outdoor elements—especially if you live in a colder or rainy climate. Use a thinset mortar or waterproof silicone adhesive.

Thinset mortar is made from a combination of cement, aggregates, and special additives designed for attaching rock, stone, tile, china, and porcelain to concrete surfaces. You can purchase it pre-mixed or in a powdered form that you mix yourself. The benefit of thinset mortar, besides its strength, is that it gives you a fair amount of working time to move the pieces around. Thinset won’t solidify for at least 2 to 4 hours (but it takes at least 24 hours to dry); however, I would still suggest working in small sections to prevent it from drying out.

Since thinset mortar has a tendency to crack, you need to find one that is polymer or latex modified. Thinset is usually white or gray.

I purchase thinset mortar at my local home improvement and tile store, under several different brand names. I’ve been happy enough with those choices to stop looking for a better alternative.

For small projects, butter the mortar onto the back of the piece with a popsicle stick and glue the pieces onto the base. For larger projects, use a trowel or other spreading tool to spread the thinset directly onto the surface and push the pieces directly into the mortar. Remember to clean off any excess mortar before grouting.

The concrete mushrooms shown in this chapter were cleaned with TSP and allowed to dry. Concrete sealer was then applied.

Pieces were buttered with a silicone adhesive and applied to the mushrooms and then left to dry for 24 hours.

Sanded grout was used, but instead of mixing the grout with water, I used a liquid latex additive to make the grout more flexible and help to ward off future cracking.

Once the piece was grouted, cleaned and dry, I sealed it with grout sealer. As always, read the directions when using this kind of product.

Try to keep the piece free from dirt by applying a coat of grout sealer at least once a year.