How To Make A Silicone Mold!

Have you ever wanted to know how to make a silicone mold?  In this article I am going to show you how to make a silicone mold and what I learned in the process.  I will show you how I built my mold and what I did when there was not enough silicone to fill my mold completely.  Most importantly, the question “Can I pour freshly mixed silicone over cured silicone?” will be answered.

Supplies needed

1.  Something you want to make a mold of.  In my case, I went to the thrift store and found a cute glass trinket holder.  
2.  Mold Star 15 Silicone kit (this is a two part kit)
3.  Hot glue gun
4.  Utility knife
5.  Gloves (optional)
6.  Something to measure and mix the silicone in.  I am using two small plastic cups and a storage container.  (originally I was going to use the green cup pictured but quickly found out I would need something larger.
7.  Double sided tape 
8.  Foam board to create the wall/border for the mold.
9.  Measuring stick (not pictured) to measure the foam board.  

Framing things up!

The first thing to do is secure to the floor of the mold.   For this project I used double sided tape.  I have since learned I could use contact paper.  I can see how this would make it much easier to remove the mold from its floor.

I cut a long piece of the foam board long enough to go around the piece.  Then I cut a slit at each corner.  You can just bend each section to create the border.  It works pretty slick.  

Then I secure the loose corner with a piece of tape.  Next I put the double sided tape on the bottom of each border side.  This helps to both secure the piece to the floor and also helps to prevent the silicone from leaking out under the border walls.

Flip it over and secure it to the floor.  Then with the glue gun, run some glue across the bottom of each wall.  Don’t forget to get the corners real good.

 Now that everything is secured and leak free, it’s time to mix the silicone.
I am using Mold Star 15.  This seems to be the silicone kit of choice for many.   It cures in approximately 4-5 hours.  Although the longer you let it site the more firm it will get.    
Stir both A and B prior to measuring out equal parts of each.  Combine both parts and mix well until there are no striations left in the container.  Approximately 3 minutes is what I would recommend.  

Once the silicone is mixed thoroughly, start pouring it into the framework. 
When pouring the silicone start in the corner and don’t move the stream around too much.  Just let the river flow and fill in all of the space.

As you may have noticed in the video, I didn’t mix up enough silicone.  This would not have been a problem had I still had enough of the product to mix up some more.  But this was not the case, sadly.  My only option was to order more to complete the project.  Which led me to the question “Did I just waste all of this silicone?  Would I be able to let this cure and pour more over the cured silicone?”  This was the question of the hour.  There was only one thing I could do.  Find out!
Order more silicone mix was what I did.  It arrived after a few days.  This was it, the big test.  It was time to find out whether or not I could pour over the existing silicone mold.  
I mixed up the silicone, just as I did a few days earlier, and poured it over the mold.  Then I let it sit overnight.  
I was very excited to release the mold from the framework.  Here is a short video of that process.  

It worked out perfectly!  You can definitely pour fresh silicone over existing silicone.  This was very exciting as that would have been a lot of silicone going to waste.  But there is something else I learned in the meantime.  

How to recycle a silicone mold

While waiting for more silicone to arrive, among other things, I did some research on making a silicone mold.  I learned you can recycle silicone molds by using them in new mold.  This will decrease the volume of silicone needed to fill the mold.  I decided to do it and this is how that worked.  
I started adding them after I had some already poured into the mold.  


I really loved creating my own silicone mold.  It allows me to create a unique piece of resin art.
Some of my takeaways when learning how to make a silicone mold were:

1.  Build the smallest framework possible for the mold while making sure to have at least 1/4 inch around the mold.  You will use much less silicone this way.
2.  Silicone is not cheap.  
3.  Always have enough silicone on hand.
4.  Choose wisely when deciding what you want to make a mold of.  (I wish I had not used such a complex piece to mold, at least for one of my first molds)

Fun Fact!

Here is a tip on how to decrease the amount of air bubbles in your silicone.  
When pouring the silicone into the mold, start low and slowly raise the cup to create a very thin stream.  This causes the air bubbles to stretch and break as they enter the mold. 

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