Edging a concrete slab is one of the final steps in finishing the slab before you allow it to sit and fully cure. Edging both seals the slab and provides a slight rounded form to the edge that will help prevent future cracking. This rounded edge also will make it easier to strip the forms from the side of the concrete later. While indoor slabs do not neccessarily have to be edged, you should always edge outdoor slabs, as they tend to be subject to more damage. The process is easy to learn, but you will have to practice the technique to learn to do it well.
Fill a bucket halfway with water. The bucket only has to be large enough to allow you to submerge and clean the hand edger you are using.
Wet the edging tool by dipping it in the water. Shake the tool to remove excess water from it.
Hold the tool by the handle with the curved downturn of the blade toward the outside edge of the slab and the flat part going toward the interior of the slab.
Slide the edger onto the concrete, pushing the curved downturn of the blade between the concrete and the wood of the form edge.
Push the edger back and forth along the edge, keeping a light, downward pressure on it at all times. After two or three times going across one area, you should see the concrete at that edge take on a smooth appearance and the round edge of the concrete should look solid--you should not be able to see any of the aggregate. Once you can see that this has occurred, lift the edging tool from the concrete and clean it in the bucket of water. Move on to the next area of the slab to be edged and repeat this process.
You can also add a wood edging strip to your slab form. Simply tack the strip onto the inside of the form before you pour the concrete. This will not provide as clear and defined an edge to your concrete slab as one finished by hand, but it can be a quick way of edging a large area.
Keep your edging tool clean. Old concrete or even concrete that has got on the tool and begun to harden can fall into the fresh concrete and create a pocket that can cause chipping or cracking later.