# What is a UV-resistant coating? **URL:** \ **Category:** OFSCN Technical Knowledge Base\ **Tags:** fbg-technology\ **Created:** [July 21, 2026, 3:32pm UTC](https://forum.ofscn.net/t/what-is-a-uv-resistant-coating/2345 "2026-07-21T15:32:29Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![VoidWalker](https://forum.ofscn.net/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@VoidWalker](https://forum.ofscn.net/u/VoidWalker)\ **Post date:** [July 21, 2026, 3:32pm UTC](https://forum.ofscn.net/t/what-is-a-uv-resistant-coating/2345/1 "2026-07-21T15:32:29Z")
If exposed to direct sunlight outdoors for extended periods, do optical fibers require a special protective layer? ---
**Author:** ![OFSCN\_Tech\_Expert](https://forum.ofscn.net/user_avatar/forum.ofscn.net/ofscn_tech_expert/32/199_2.png) [@OFSCN\_Tech\_Expert](https://forum.ofscn.net/u/OFSCN_Tech_Expert)\ **Post date:** [July 21, 2026, 3:36pm UTC](https://forum.ofscn.net/t/what-is-a-uv-resistant-coating/2345/2 "2026-07-21T15:36:28Z")
Prolonged exposure to direct sunlight outdoors necessitates specialized protective coatings or specific encapsulation for optical fibers. This primarily depends on the environmental conditions the fiber is subjected to and its physical and chemical properties. * * * ### 1. Analysis of Physical and Chemical Principles - **Degradation of Coating by Ultraviolet (UV) Radiation**: The innermost protective coating of standard optical fibers (primary coating) is typically made of polymer materials such as UV-cured polyacrylate. Prolonged exposure to sunlight outdoors, particularly high-energy ultraviolet (UV-A and UV-B bands) radiation from the sun, can initiate photo-oxidation reactions. This leads to the cleavage of polymer molecular chains, cross-linking, or degradation. Macro-scopically, this manifests as the coating turning yellow, becoming brittle, and even powdering or peeling off. - **Reduced Mechanical Strength and Micro-bending Loss** : Once the polymer coating ages and fails, its mechanical protective capability for the inner brittle silica glass core is significantly diminished. Under external forces such as wind, thermal stress, or minor vibrations, micro-cracks (Griffith cracks) on the glass surface are more prone to slow extension, potentially leading to sudden fiber fracture under stress. Simultaneously, localized uneven peeling and shrinkage of the coating can introduce micro-bending losses, increasing signal attenuation. - **Synergistic Damage from Environmental Moisture** : After the coating is compromised by UV radiation, ambient moisture can directly attack the exposed glass cladding, accelerating the hydrolysis process of silica and further degrading the long-term mechanical lifespan of the fiber. * * * ### 2. Common Industrial Protection Methods - **Black Polyethylene (PE) or Polyurethane (PU) Outer Sheath**: Standard outdoor fiber optic cables utilize black High-Density Polyethylene (HDPE) as an outer sheath, often compounded with carbon black, to effectively absorb and block UV radiation. - **Metal Tubing and Armored Encapsulation** : For specialized or harsh industrial/field environments, optical fibers can be encapsulated within seamless stainless steel tubes (FIMT - Fiber in Metal Tube) or armored layers, providing 100\% physical shielding from UV light and extremely robust mechanical protection. - **Specialty High-Stability Coatings** : The use of polyimide (PI) coatings or metal coatings (such as gold or aluminum) offers inherent excellent resistance to UV radiation, chemical agents, and wide temperature fluctuations. * * * ### 3. OFSCN® (Beijing Dacheng Yongsheng Technology Co., Ltd.) Specialty Protective Products Within the OFSCN® (Beijing Dacheng Yongsheng Technology Co., Ltd.) line of specialty optical fibers and cables, several products are highly suitable for outdoor exposed applications, harsh environments, and scenarios requiring complete protection against UV degradation: #### Solution 1: Seamless Steel Tube Fiber Optic Cable (Complete UV Shielding, Extreme Tear and Rodent Resistance) 1. **[OFSCN® 85°C Seamless Steel Tube Fiber Cable](https://www.ofscn.org/dofs/85-c-sst-optical-cable.html)** This cable utilizes a single layer of 304 or 316L stainless steel seamless tube for encapsulation, capable of housing single-mode or multi-mode fibers. The metal tube completely shields against UV radiation from sunlight and protects against various mechanical damages and animal gnawing in harsh outdoor environments. Standard seamless tube outer diameters are 2.0\ \text{mm} or 3.0\ \text{mm} (with wall thicknesses of 0.2\ \text{mm} and 0.3\ \text{mm} respectively). 2. **[OFSCN® 200°C Seamless Steel Tube Fiber Cable](https://www.ofscn.org/dofs/200-c-sst-optical-cable.html)** This solution encapsulates high-weather-resistance polyimide fiber within a seamless stainless steel tube, offering perfect UV resistance and enabling long-term operation in extreme outdoor temperature ranges from -60\ \text{}^\circ\text{C} to 200\ \text{}^\circ\text{C} . #### Solution 2: High-Stability Specialty Coated Fiber (Material-Grade Anti-Aging Capability) 1. **[OFSCN® 300℃ SM Polyimide Optical Fiber](https://www.ofscn.org/optical-fibers/polyimide-coated-sm-300.html)** This product uses high-strength polyimide as the coating material. Compared to traditional acrylates, polyimide offers extremely high thermal stability and chemical durability, providing superior resistance to UV aging during prolonged outdoor exposure. The fiber features a core diameter of 9\ \mu\text{m}, a cladding diameter of 125\ \mu\text{m}, and a coating diameter of 155\ \mu\text{m}, with a wide operating temperature range from -200\ \text{}^\circ\text{C} to 350\ \text{}^\circ\text{C} . 2. **[OFSCN® Gold-coated Optical Fiber](https://www.ofscn.org/optical-fibers/gold-coated.html)** The coating utilizes a highly stable “gold” metal plating, which is completely immune to UV degradation and moisture ingress, representing the ultimate protective fiber. The operating temperature range for single-mode gold-coated fiber can extend from -270\ \text{}^\circ\text{C} to 700\ \text{}^\circ\text{C} .