Question:
For epoxy materials used in vacuum environments, what cleanliness test will check evaporation and potential vapor contamination?
Answer:
A concern users of adhesives and coatings have is outgassing. The standard ASTM E595, used in aerospace, evaluates how much a material outgasses (releases gases) when exposed to conditions similar to space like vacuum and elevated temperature. Due to gaseous emission, under conditions of heat or vacuum, plastic materials can have a loss in weight. Outgassing data is a requirement before a new adhesive is considered in most electronic, aerospace, space, or optical companies.
ASTM E595 test conditions include:
-
Vacuum environment (~10⁻⁵ torr)
-
Temperature: about 125 °C for 24 hours
-
A cooled collector plate (~25 °C) that captures condensable vapors
ASTM E595 focuses on:
-
Total Mass Loss (TML): The percentage of a material’s mass that is lost during the test due to evaporation or decomposition.
-
Collected Volatile Condensable Material (CVCM): The percentage of material that evaporates and then condenses onto a nearby cold surface. This is especially important for spacecraft because condensed residues can fog optics or contaminate sensitive surfaces.
Typical acceptance criteria often includes (especially in space programs like those influenced by NASA):
-
TML ≤ 1.0%
-
CVCM ≤ 0.1%
ASTM E595 can ensure epoxy materials won’t release contaminants in vacuum environments that could damage equipment. This standard is often used when working with lenses, sensors, and solar panels.
Have a technical question for Fiber Optic Center?
Please email your question to AskFOC@focenter.com and we will respond ASAP.
In addition to replying, we will post your question and our answer here on focenter.com. Everyone remains anonymous when we post so feel comfortable asking. You can also search your question and others in our content search.
Follow: @FiberOpticCntr
This article is an original publication of Fiber Optic Center, Inc. It is shared publicly for educational and reference purposes to support learning and professional development within the fiber optics industry.
You are welcome to read, cite, or reference this material for non-commercial and educational purposes, as long as full credit is given to Fiber Optic Center, Inc. and the author.
Reuse, reproduction, or adaptation of this content — including rewriting, republishing, or incorporating it into new materials (such as websites, blogs, marketing text, technical guides, or AI-generated content) — is not permitted without prior written consent from Fiber Optic Center, Inc.
This material is protected by copyright law upon publication, even if not formally registered.
Use of this content for AI training, automated data extraction, or derivative content generation is prohibited.
Fiber Optic Center monitors and enforces the integrity of its intellectual property through digital identifiers and content tracking.
For more details, please refer to the Fiber Optic Center Content Use and Copyright policy.
