I recently found a heart mold in a thrift shop for $1.00. The mold is used to make ice cubes and has Ikea's name on it. I like to make different items out of cement/concrete so decided to put some excess mix into the mold one day. The result was nicely formed, hard, easily worked with hearts! I decided to paint them and then got the idea of adding letters to the hearts. This instructable shows all the steps in these processes.
Step 1: Gather Materials
The usual mixing tools, buckets, water, measuring cups/cans, stirrers, spoons, cement mixtures of various kinds, etc.
Step 2: Mix Substrate of Choice With Water
I found that just about any cementious mix can be used for the hearts. I used: sand/cement mixture (mortar); grouts, both sanded and non-sanded; tile set mortar; fix it all; and various combinations of all of the above. Regular concrete mix with aggregate wouldn't work for obvious reasons.
Step 3: Add Mixture to Mold
I started out filling the molds all the way to the top. But later found I preferred only half filled molds. Saves on the amount of mix and is easier to manipulate. A regular spoon is a good filling tool. It's up to you. Let the hearts set for 18 to 24 hours at least. I try to mix in the morning, and then de-mold the next morning.
Step 4: De-Mold Your Hearts
Voila! Many hearts (16 per pour) to decorate and use in various projects.
Step 5: Painting The Hearts
First, a primer is used. I chose a white house paint that I had left over from a previous job. Any white could be used. Then I used regular acrylic craft paint and a good brush so as to minimize brush marks. More than one coat may be needed, depending on the thickness and make-up of the paint used. It dries very rapidly so is not a problem. After drying, a few coats of gloss water based polyurethane is applied and allow to dry. If letters are added, they should be covered with the polyurethane as well. While this step is being done, another mold has been poured.