Techniques for reducing silicone bubbles in molds without a vacuum machine

Bubbles in liquid silicone during the mold opening process can seriously affect the aesthetics of silicone molds, which makes us helpless, especially for people without vacuum machines who are confused

Firstly, let's analyze the reasons for the formation of bubbles. The first reason is that the bubbles introduced when mixing silicone and curing agent are not completely eliminated. Therefore, when stirring, we need to stir in one direction and let it stand for a period of time after stirring, allowing the bubbles to float up on their own.

Secondly, when pouring the glue, it is best to let the liquid silicone flow slowly in a filamentous shape. This can eliminate bubbles while pouring the glue. After pouring, any bubbles on the surface can be punctured with a toothpick.

Besides, we can also extend the curing time by controlling the ratio of silicone to curing agent, giving more time for bubbles to naturally dissipate. For example, if the ratio of silicone to curing agent is 4%, we can reduce it to 2%. This way, the cross-linking time of the silicone in the early stage of the mold will increase, and the air in the mold will gradually be discharged to reduce bubbles.

The second reason is that the formula of liquid silicone raw materials contains a small amount of volatile impurities, which can easily vaporize and form bubbles during heating and curing. Therefore, we try to use room temperature curing or low-temperature baking methods during curing to let these impurities evaporate first, so as to reduce bubbles.

Some mold makers also have the habit of diluting silicone oil with silicone oil to increase the fluidity of liquid silicone and facilitate the elimination of bubbles (low viscosity silicone is more prone to air bubbles). However, we recommend that the maximum amount of silicone oil added should not exceed 5%, because excessive addition of silicone oil can damage the molecular weight of silicone, resulting in silicone molds that are not resistant to acid, alkali, and aging.