Concrete Mold Release Agent
If you’re using fiberglass or aluminum molds, you will have to prepare your molds to ensure you can take them apart after there poured and have cured. Not maintaining or prepping your molds before use will shorten their lifespan and new molds are not cheap.
Use either a brush or spray bottle to apply the mold release prior to pouring. There are 2 different oils I use. Castor oil mixed with denatured alcohol or 91% rubbing alcohol for latex rubber molds and non-detergent motor oil for aluminum molds.
Castor Oil Concrete Release Agent
The mix ratio of castor oil and denatured alcohol is 8 parts denatured alcohol to 1 part castor oil. Spray or brush it on the inside of the latex rubber before pouring cement in. Make sure there are no puddles inside the mold after the mold release is applied.
The concrete won’t set where the puddles are and it will be sandy when you take the ornament out of the mold. Never, ever, use any motor or petroleum-based oil on latex rubber. That will ruin the rubber. Also keep the latex mold out of direct sunlight or the rubber will weaken.
Aluminum Mold Release
Aluminum molds are pretty straightforward. Just brush on non-detergent motor oil and make sure there are no puddles and then it’s ready to be poured. The thing with aluminum molds is they are not as detailed as latex rubber molds, but in some cases more expensive.
I always preferred fiberglass latex rubber molds over aluminum molds. A detailed piece is more fun to paint, plus it looks a lot better when done and you can get more money for it if you plan on selling it.
Mold Release for ABS Plastic Molds
For this type of mold, you can use Pam cooking spray (Link To Amazon). Just cover the inside with the spray and use a paper towel to wipe as much of the cooking spray out as you can. Avoid puddles or the concrete will not “set” right and you will have a sandy finish instead of a smooth finish.