Maintenance of Lens Mount Weather Sealing Gasket Aging and Deformation

1. The only defensive mission of the rubber ring (Mount Gasket) behind the bayonet

No matter how well-sealed the front lens group and the zoom ring are, if water leaks at the flange connection that engages the camera body, all defenses will instantly be reset to zero:

• Physical gap of metal to metal:
• Between the stainless steel mount of the camera body and the brass chrome-plated mount of the lens, no matter how precise the processing is, there is still a mechanical activity tolerance gap of tens of microns ((\mu\text{m})) in terms of microscopic tolerances;
• Capillary Action:
• Once rain or splashing water flows to the edge of the gap on the bayonet joint surface, the water molecules, pulled by the strong liquid surface tension, will be violently sucked into the body through the capillary along the gap like a micro straw**!
• Immediately inside are the highly sensitive electronic contacts, sensor anti-shake voice coil motor and motherboard power supply circuit. A trace amount of conductive water vapor can cause an instantaneous surge, short circuit and explosion!
• Physical sealing barrier of rubber seal:
• An extremely thin O-Ring Gasket (Rubber Skirt/O-Ring Gasket) protrudes from the outer edge of the professional-grade weatherproof lens mount;
• When the lens is rotated and locked into the fuselage, the rubber edge is squeezed hard by the hard front plate of the fuselage and undergoes slight elastic deformation, completely filling and sealing the metal bonding gap in physical space.

2. Aging physical dynamics of hardening and brittleness of rubber sealing rings

This slender rubber ring withstands the harshest environmental torture in the entire camera system:

1. Frequent rotational shearing torque wear: Every time the lens rotation buckle is replaced, severe contact friction and torsional extrusion occur between the rubber skirt and the metal shell of the fuselage;
2. Ultraviolet photolysis and ozone oxidation (UV & Ozone Aging): The unsaturated double bond molecules in the rubber are bombarded by high-energy photons of sunlight's ultraviolet rays to cross-link and solidify, causing the rubber to gradually lose elasticity;
3. Seawater salt spray crystal wear: Tiny sodium chloride salt particles in the sea breeze are embedded in the rubber micropores, and the salt crystals harden and cut the rubber microstructure like small blades;

• Deterioration results: The rubber gradually becomes hard and brittle, and tiny jagged gaps appear on the edges. Finally, when disassembling and assembling the lens, the entire section teared, degummed and broke! Shooting in the rain with a lens that has lost its sealing protection is like running naked.

3. Daily self-inspection of microscopic cracks and nourishment and maintenance of trace amounts of high-purity silicone grease

Develop a professional habit of regularly checking your lens butt seal:

• High light flashlight fingertip stretching method:
• Take off the back cover of the lens, and use the pads of your clean thumbs to gently stretch the rubber skirt on the outer edge of the bayonet outward under a strong desk lamp;
• Carefully observe the root and outer edge of the rubber skirt: if you find that the rubber surface has lost its original soft luster, becomes shriveled and white, or has hair-like Micro-Cracks or tiny chips, it means that the sealing performance is on the verge of bankruptcy.
• High purity food grade silicone grease (Silicone Grease) maintenance skills:
• It is strictly prohibited to use any petroleum-based engine oil, cooking oil or butter (petroleum solvents will cause the rubber to swell, deform and turn into mud!);
• High-purity, pure and transparent anhydrous silicone grease (such as Shin-Etsu high-purity silicone grease) must be used;
• Dip a cotton swab into a very small amount of invisible silicone grease (one-tenth the size of a grain of rice);
• Apply very gently along the rubber sealing ring and slide it all the way around, then wipe off all excess grease with a dry, dust-free cloth, leaving only a nano-scale molecular lubrication protective film on the rubber surface;
• Completely isolates air oxidation, allowing the hardened rubber to regain baby-like flexibility and elasticity, and the damping is smooth and silent when rotating and changing lenses.

4. Surgical specifications for self-replacement of damaged rubber seals by the original manufacturer/sub-factory

If the rubber ring is broken and incomplete, there is no need to spend a lot of money to send it to after-sales service. Ordinary photographers can replace it by themselves:

1. Acquisition of accessories selection:

• Search for exclusive accessories for the corresponding lens on the e-commerce platform (such as "Canon EF 24-70 II mount rubber ring", "Sony 70-200 GM mount sealing ring");
• Confirmed to be made of original factory open molded high elastic fluororubber.

2. Lossless elimination of old circles:

• Use a pair of fine-tipped anti-static plastic tweezers (it is strictly forbidden to use sharp metal scalpels to avoid scratching the precision metal flange of the lens);
• Pick up a corner of the remaining old rubber ring, pull it out completely, and use a cotton swab dipped in isopropyl alcohol to thoroughly clean the sand and debris in the rubber bottom groove.

3. The Stretch Fit:

• The new rubber ring has no openings and is a complete elastic ring;
• First insert one side of the rubber ring into the fixing groove at the root of the lens mount;
• Press and hold with your thumb, and use the fingertips of the other hand to gently and evenly stretch the ring outward along the circumferential edge, and then insert the entire ring into the groove of the base;
• Use the flat end of a toothpick to slide and press around the circumference to confirm that the rubber ring is completely flat and falls into the deep groove without any distortion or undulations. The entire all-weather defense system is instantly in place with full health!

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