Pinterest is brimming with DIY concrete projects, from planters to home décor to jewellery. Many of those do not require any special tools and are very affordable. You may just take a plastic cup, put a cement mix in it and voila your handmade concrete candleholder is ready (well, in about 12 hours.)

But if you are looking for more consistent quality and sleeker look you might consider using silicone rubber molds. They are flexible and withstand multiple usages, allowing you to get consistent results and produce a professionally looking batch of products, be it flower pots, door knobs or pendants. Molds are also cleaner and faster way to work with concrete. The post-production sanding is minimal and doesn’t take much effort either.

There are several types of silicone molds available in online shops, including tin-cured silicone molds and platinum-cured ones. Both types vary in performance and durability, with platinum silicone rubber being more flexible and resistant to tearing. Platinum rubber molds also produce smoother surface in the cast products.

Although molds are stretchy and withstand many castings, there are several factors that may contribute to tearing, such as release agent used (or not used) to ease the pulling, abrasive particles in cement mix, leaving the molds folded or not cleaning them. 

Here are a few tips that will help your molds last longer and work better.

1. For the molds to retain their shapes store them in a single layer, do not pile them up. 

2. After using clean the mold with tepid water and soap, don’t use abrasive products. Don't forget to clean the mold between the castings, especially when using pigments or different colour cement. Gently remove the dry particles of concrete with soft sponge and soap to avoid scratching the silicone surface. 

3. Keep your molds away from direct sunlight as UV may cause damage to silicone.

4. Don’t pull at the mold too strongly. Release the cast product by gently moving around and unsticking the mold rather than pulling strongly at one end. 

5. Platinum-cured silicone molds can be used with different materials, such as cement, resin, wax. However, it is recommended to dedicate mold to one material to avoid ‘cross-contamination’. For example, if you are using it first with concrete and then with epoxy resin, you may end up with concrete particles in your resin cast.