Degassing Resins to Reduce & Eliminate Bubbles in Resins – A Guide
When working with resins a critical step to getting a smooth finished product is to ensure your resin mix is free from air bubbles. After all, any air bubbles in the resin can create deformities and rough texture in your cured resin. This guide will cover ways we can degas resins and the benefits or drawbacks of various methods.
Do You Need to Degas Your Resin ?
Before considering buying equipment and creating additional work with your resin casting, first you should consider if you need equipment to degas your resin. Typically air bubbles are introduced into the resin during mixing and transferring material. If you can design your work to reduce or eliminate creation of any air bubbles and do not find your resin texture rough appearing like the parts shown here then you may not need to consider the following tips and equipment options for degassing your resin.
Method 1 for Degassing Resins - Vacuum Suction
The first option you have for removing air or gases from a resin is to pull a vacuum on the resin. Using a vacuum will cause air bubbles that have become entrapped to be pulled from the material you have the suction being pulled.To be able to pull an adequate vacuum (which will depend on the type of resin and other factors) you can use a variety of equipment options but typically will aim for a vacuum of 26 in Hg. Common uses for vacuum include higher viscosity materials like silicone rubber. The benefit with vacuum degassing is that it will remove air from the material, how easily air will escape will depend on the surface tension and viscosity of the material.The benefit of removing air is that the material can then be placed into a mold without having to wait until it gels because the resin will have had air bubbles removed.
Method 2 for Degassing Resins - Pressure
An alternative or additional method to pulling a vacuum to remove any air entrapped in your resin is to pressurize the resin. Pressurizing the resin doesn’t actually remove the air from the material but alternatively compresses any air bubbles that were caught in the mixture to the point where they do not matter. The potential downside to this method is that you will often times have to leave your resin under pressure in your mold until it begins to gel over so that the air bubbles cannot expand and create problems during the time the resin sets up. The downside to pressure for degassing resins is that it can create changes to your sculpt due to the pressure which can be a problem depending on the type of resin casting your doing.
Method 3 for Degassing Resins - Pressure and Suction
A third way to degas resins is to actually make use of both suction and pressure. By leveraging the benefit of removing air bubbles via suction and then setting the mold up under pressure until your resin gels you essentially are providing additional assurance that no air pockets will be present. Many find that just pressure is sufficient for their resin degassing but often times you may need to test to determine if pressure, vacuum, or both are needed for your particular resin application.
Equipment Option 1 for Degassing Resins - An ASME Vacuum Rated Pressure Pot
The first option you have available for degassing resins whether it be for vacuum or pressure is a vacuum rated ASME pressure pot. The key thing to verify before considering a pressure pot for the job is to ensure it is rated for vacuum applications. You also want to ensure that the pressure pot has a high enough rating to withstand the vacuum you intend to pull. For example these Binks pressure pots are ASME rated at -1 atmosphere vacuum rating and up to 110 psi making them sufficient for most degassing processes where pressure is typically 60 psi and vacuum is usually 26 inches of mercury (1 atmosphere is 29 inches of mercury).
The benefits to a pressure pot are that they are an affordable way to degas a variety of resins from a small part or two which you can potentially do inside a 2 gallon pressure pot to a large batch of material in a 30 gallon paint pressure pot for larger production runs. Whatever your application, a pressure pot can provide an easy to use solution to degas your resins whether it be via pressure or suction but will require you to have an air compressor for pressurizing the pot and/or a vacuum pump to pull a suction on the pressure pot.
Equipment Option 2 for Degassing Resins – A Vacuum Chamber
A vacuum chamber offers the ability to pull suction on a resin to remove any air bubbles that have become entrapped in the material. A vacuum chamber will only allow for pulling suction compared to a pressure pot where given you have a vacuum pump.