QUESTION: Why does my epoxy have crystals in it?
ANSWER:
Crystallization of liquid epoxy is a known phenomenon that frequently surprises users who are not very familiar with epoxies. Crystallization may look like crystals, snowflakes, cloudiness, fog, turbidity, and even a solid, or a solid sediment, in the epoxy resin.
The reason some epoxy resins crystallize has to do with their ‘super-cooled’ nature – they are supposed to be solids at room temperature, but have remained liquid below their solidification (freezing) point. Therefor super-cooled liquids have a natural tendency to crystallize.
The timing of crystallization is highly variable and unpredictable. Factors effecting crystallization include resin purity, viscosity, additives, moisture content, the presence of ‘seed’ crystals, and environmental variables such as storage temperature and even a sudden cold shock.
Crystals can be easily eliminated by increasing the temperature of the liquid resin to about 50°C (about 122°F) for a period of hours or until all signs of the crystals are gone. Allow the resin to cool back to room temperature, and proceed to use normally. There is nothing about crystallization that is damaging to the epoxy. It is the same as water freezing, and melting ice: the water is exactly the same before and after crystallization.
ADDITIONAL CONTENT & RESOURCES:
- Category Resource: FOC Epoxy Page
- Find More Information in this Blog: Helpful Epoxy Tips (and a Few Tricks)
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.
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.
