I did some tuck-pointing recently on some small cracks. I wanted to keep the fill as tidy as possible, so I mixed up a pretty sticky batch of thinset and used a glue syringe to push it into the cracks. The thinset flows well and sticks tenaciously; also, it’s a good color match with the old mortar. But the key to getting this all to work smoothly was to insert the syringe in a caulk gun. As shown in the drawing (right), I put a large washer into the business end of the caulk gun to give the syringe cylinder something to bear against. The mechanical advantage gained by using the caulk gun to push the thinset helped a lot.
Don Mathis, Macomb, IL