How to Build Fake Pond Rocks
- 1). Cut out pieces of foam into rock-shaped pieces with a saw. Make them slightly smaller than you want the finished rocks. You will be applying a thick cement coating that will increase their size.
- 2). Round and smooth the rock shapes with a rasp.
- 3). Mix a small batch of cement in a mixing bucket, following the mixing instructions on the bag. It should have the consistency of peanut butter.
- 4). Spread the cement over the surface of a few foam rocks with a small trowel. Work in small batches to avoid wasting cement.
- 5). Check the hardness of the cement every few minutes. You are looking for the point when it has almost hardened but can still be scratched with your fingernail.
- 6). Buff each rock smooth with a wet rag once it has reached the semi-hard state where it can be scratched.
- 7). Allow the rocks to completely harden. This will take a few hours.
- 8). Stain the rocks to the desired color with concrete stain. Brush the stain on, then wipe it off with a clean rag after a few seconds. If it is not dark enough, apply a second coat of stain.
- 9). Brush a coat of glossy cement varnish on the rock to seal it and give it a shiny outer layer.