Should I use plastic resin molds or silicone resin molds for my resin jewelry and crafts?
Originally published March 2013. Updated August 2018.
Knowing the difference between plastic and silicone resin molds is important to getting the results you want. Both types of molds can work with a variety of resins, but knowing the limitations of each is essential to making sure you get the results you want.
These reusable resin molds are usually made from polypropylene or polyethylene sheet plastic. They are generally made from a template and are partially flexible.
Inexpensive. Plastic resin molds usually cost less than $10 each. (Many for under $5!) If or when you damage a mold, you’re usually not out a lot of money to replace it.
Easier to work with. Plastic molds are a great place for new resin crafters to start. They are easier to demold and care for as compared to silicone resin molds.
Castings are not likely be shiny and bright. The surface of the casting that is touching the surface of the mold may not be as shiny as you want once removed from the mold. You will either need to recoat with another layer of resin or cover with a layer of resin gloss sealer spray.
Can easily be scratched. While it is helpful that the plastic is flexible, the softness makes it easier to scratch the surface. Something like a toothpick or a fingernail can leave a noticeable gouge if you are not careful.
Difficult to make your own. Making your own plastic molds requires vacuum forming sheet plastic around a template which requires specialized equipment.
These reusable resin molds are made from two part silicone and can last for many years if cared for properly.
Very flexible. Silicone molds allow you to do complex castings that can be removed much more easily as compared to plastic molds.
Custom molds. You can purchase two part silicone yourself and mold anything you want to (assuming you have a model).
Castings may come out shiny. I say may here because the original model used to make the mold must be shiny. If it is (like with our geometric silicone resin molds), then your casting should come out just as shiny as the original.
Expensive. Silicone molds can be two to three times the price of a plastic mold.
Requires more care. Silicone molds must be cleaned after use and stored flat in a cool, dry area. Here are some tips for caring for your silicone resin molds.
May require pressure casting. Unless you’re using a clear silicone mold, you might not see all the bubbles in your resin when casting it into silicone. You might need to use a pressure casting setup to make sure all your bubbles are handled before the resin starts to cure.
So which kind of resin mold should you choose?
If you’re a beginner, I recommend starting with a plastic resin mold. They are inexpensive and if you make a mistake (like your resin doesn’t cure), you’re not out a lot of money.
Once you get better with resin, a silicone resin mold can be a great ‘collection piece’ to add to your mold collection. It will last for hundreds of castings.
Pro tip: if you make a casting from your plastic mold that you really like and you want it to be shiny, complete the casting, get the shine you like, then mold it in silicone.
Unpublished Blog Posts of Resin Obsession, LLC © 2018 Resin Obsession, LLC