One of the biggest problems facing many small scale mould makers is air bubbles within their silicone mould. The bubbles inside the silicone rubber mould itself are generally not really a major issue. The issue is if the air bubbles form at the casting surface making the mould unusable.
There are numerous solutions to use to guarantee bubble free silicone moulds:
1) Special pouring techniques
2) Applying compressed air
3) Using Vacuum to get rid of bubbles
4) Using pressure to make air into solution
The top where casting materials meet silicone moulds is the most important part. It is actually therefore essential that additional care is provided to guarantee no bubbles form when pouring the silicone rubber in the mould box and on the model. It is crucial to never simply pour the rubber over the top of the model all at once. Start by pouring a tiny amount of rubber into the mould box and begin tilting it in numerous angles to create the rubber slide total surfaces. This wets the top of the model by using a fine film of rubber and then any air bubbles can be easily seen and popped having a pin or paint brush.
You can even work with a paint brush to use this first fine film of rubber to the surface of the model. Opt for the method which works well with your cookie cutter.
When you are satisfied that all the bubbles are already popped you can pour the other mould making rubber in the mould box. Pour from as high a point as you possibly can inside a fine stream in order that any bubbles from the mixture will pop around the way down. Aim this stream into a corner of the mould box and never along with the model.
For those who have use of an air compressor you own an effective way of popping air bubbles. Ensure you have about 30psi pressure as well as a small nozzle tip and after pouring the very first small amount of rubber into the mould box blow the material within the model to wet the top inside a similar approach to the very first method. The 1st film of rubber should be bubble free.
Bubbles are often a direct result air beaten in to the rubber throughout the mixing process. Make sure that you stir the mixture in the steady and slow action. There will still be air in the mixture however and this could be removed through the help of a vacuum chamber.
These vacuum chambers work with a vacuum to suck out any air bubbles from the mixture and bring them to the outer lining where they can be easily removed. Each vacuum chamber has their very own 41dexfpky on the way to apply it but this is a guide:
1) Utilize an oversized container for mixing. Allow for the mix to double in dimensions when put into the chamber.
2) Mix both part A and part B within the container and set into the chamber. Close the chamber and commence the vacuum pump.
3) The mixture begins rising to the top of your container. All of the air bubbles within the mixture will rise on the surface. Because the mixture approaches the top of the the container release the valve which breaks the vacuum and the mixture will drop to the bottom as well as the air bubbles will pop. Do this 2 to 3 times to make certain all bubbles are removed.
4) Release the vacuum the last time as well as take the mixture out of your chamber. It is now ready for pouring.
Utilizing a vacuum chamber is usually only possible for cake rolling pin which go on a fair timeframe setting. A few of the quicker setting silicone rubbers will set too quickly and also you won’t have the a chance to vacuum the bubbles out. Be sure you check the label about the product you happen to be using.