ElastaPro makes low outgassing silicones that meet ASTM E595 requirements and are specially formulated and processed to minimize the release of volatile compounds under vacuum conditions and/or heat. In addition to spacecraft, applications include aerospace, defense, electronics, optics, and medical devices.
ElastaPro produces low outgassing silicones at our Made in USA manufacturing facility in Santa Fe Springs, California and offers these specification grade materials as solid silicone sheet and uncured silicone compound. Choose ASTM E595 silicone in following durometers (hardness) on the Shore A scale: 40, 50, 60, and 70.
Keep reading to learn more and contact us for a quote.
What is Outgassing?
Outgassing refers to the release of volatile organic compounds (VOCs) from a material, typically at reduced pressure (vacuum) or elevated temperatures. Volatiles include residual solvents from processing, unreacted monomers, plasticizers and additives, and degradation products from thermal or environmental stress. Sometimes, outgassing is called off-gassing instead.
In vacuum conditions such as space, the released vapors from outgassing can condense on sensitive surfaces such as optical lenses, sensors, or electronics. This can cause contamination, but it can also degrade performance or result in mission failure. Silicone elastomers are chemically stable and heat resistant, but they can contain low-molecular-weight siloxanes that are prone to volatilization.
What is ASTM E595?
ASTM E595 defines a standard test method for Total Mass Loss and Condensable Volatile Materials from outgassing in a vacuum environment. ASTM International developed this test standard in cooperation with NASA, and it simulates the conditions that materials such as silicones may face when used aboard spacecraft.
Importantly, ASTM E595 provides a consistent, repeatable way to measure how much mass a material loses in avacuum due to outgassing, and how much of that lost mass condenses on nearby surfaces. There are three key metrics.
- Total Mass Loss (TML) is the percentage of initial mass lost by the specimen during the test. This measurement is important, but TML alone does not indicate contamination risk. Some volatiles may not condense on cold surfaces but dissipate harmlessly.
- Collected Volatile Condensable Material (CVCM) is the percentage of material that condenses on a cooled collector plate. CVCM is critical measurement for optical and thermal systems since even a small amount of condensable material can fog lenses, degrade solar panels, or alter thermal emissivity.
- Water Vapor Recovered (WVR) is an optional measurement for materials, such as silicones, that absorb and release water vapor. WVR is less critical in space environments, but it’s important for applications (such as electronic assembly) that may occur in humid conditions.
ASTM E595 provides the framework for measuring these values, but NASA’s own standards define acceptable limits for spacecraft. For example, NASA-STD-6016 specifies that a material must meet the following criteria to be considered low outgassing.
- TML ≤ 1.0%
- CVCM ≤ 0.10%
This dual structure of ASTM providing the test method and NASA providing the acceptance criteria ensures consistency and practical usability across the aerospace sector.
Where are Low Outgassing Silicones Used?
Low outgassing is important for spaceflight and aerospace applications, but engineers also need low outgassing silicones for electronics and semiconductors, medical devices and pharmaceuticals, and optical and precision instruments.
Aerospace and Spaceflight
Outgassed volatiles can condense on telescope mirrors, star trackers, and camera lenses, reducing transmission and resolution. These substances can also condense on thermal control surfaces such as radiators or solar arrays and alter emissivity and absorptivity. In crewed spacecraft, outgassed volatiles may pose toxicity or odor concerns.
Electronics and Semiconductors
In microelectronics, outgassed siloxanes can deposit on contacts or printed circuit boards, leading to insulation failure or corrosion. The low outgassing silicones that ElastaPro provides are used for enclosure sealing, but the electronics industry also needs materials with low levels of outgassing for potting compounds, conformal coatings, and encapsulants.
Medical Devices and Pharmaceuticals
ASTM E595 does not apply to medical devices or pharmaceuticals; however, these industries are also concerned about the migration of volatile compounds that could interfere with sterile environments or analytical equipment. Low outgassing silicones can help improve biocompatibility and analytical purity, but other standards and requirements also apply.
Optical and Precision Instruments
Microscopes, laser systems, and satellites all require pristine optical surfaces. Even trace condensation can cause scattering or absorption, degrading performance. Silicones with low outgassing may be required for these applications.
Ask Elasto Proxy for Low Outgassing Silicones
ElastaPro makes ASTM E595 silicone and supplies these specification grade materials as solid silicone sheet and uncured silicone compound. Solid silicone sheets arrive ready for die cutting and come in thicknesses ranging from .010” to .500” and widths up to 60”. Uncured silicone compound can be molded, extruded, or calendered.
At ElastaPro, we manufacture materials in accordance with our ISO 9001:2015 and AS9100D Certified Quality Management system (QMS) and provide a Certificate of Analysis (COA) with each batch for traceability. Contact us to request a quote, discuss your applications, or receive additional information about how we serve your industry.
