How to Make Your Own Skim Coat for Portland Cement
- 1). Determine the area for which you are going to skim coat. If you are covering an existing concrete floor and are simply covering up old cracks or helping to level out dips and valleys, you can use a simple concrete and water mixture. If you are skim coating walls, such as with bricks or masonry blocks, you can add a little lime into the mixture to create a more sticky compound that more readily sticks to the surface, allowing for ease of use.
- 2). Mix your skim coat mixture with a low-speed drill. A high-speed drill will whip air bubbles into the mixture, which will pop as the skim coat dries on your chosen surface, leaving pin holes behind. Add water in small amounts and aim for a consistency just this side of thick peanut butter. The goal is to have it spreadable, but not soupy or runny. Let the mixture set for several minutes after mixing it the first time to let the water completely soak into the concrete, then mix it an additional time before spreading.
- 3). Add lime into the mixture. The amount of lime is somewhat irrelevant, but as a general rule you can add a couple of handfuls of lime to a five-gallon bucket of skim coat mixture. The more lime you add, the stickier the skim coat mixture will be. Some experts choose a 5-to-1 mixture of cement to lime. Otherwise, you can mix the skim coat batch in the same way you would with a normal cement and water base.