Paper towels will scratch a coated filter. So will a dry shirt hem and that folded receipt at the bottom of the bag. If the glass has a multi-layer coating, you treat the face like front-element glass — not like a phone screen you wipe on your jeans.
I'm Leo Liang. I run XT Filters. The mail about cleaning usually arrives after someone bought a UV or clear, left it on for a month, and then watched a fingerprint turn into a haze they tried to rub out with whatever was nearby. The filter was doing its job. The wipe was the problem.
I keep an XT996S on my GH7's 12–40 for seaside evenings and street days. That coating is what I am protecting when I clean — not because I ran a lab wipe test, but because the glass is cheap to replace and the habit is cheaper than either.
What actually scratches
Coatings fail the same boring ways every time:
- Dry abrasion. Tissue, paper towel, or a dirty cloth dragging grit across the face.
- One hard circular scrub when you are impatient.
- Cleaning fluid poured onto the glass so it runs into the ring and under the retaining lip.
Dust itself is often harder than the soft coating layer. If you wipe before you blow, you are dragging grit. That is the whole story. Brand names on the bottle matter less than whether grit moved under pressure.
I do not clean on a schedule. I clean when I can see a print, a salt film after wind near the water, or a smudge that shows up as a soft blob against a bright sky. Leaving a clean filter alone is fine.
The short routine I actually use
Fifteen seconds if the glass is only dusty. Longer if something oily landed on it.
- Blow first. Bulb blower, not your mouth. Mouth spit turns dust into mud.
- Look again. If the face is clear, stop. Do not invent a wipe.
- One drop of fluid on the cloth, not on the glass. Lens fluid or a dedicated filter fluid. The cloth should be barely damp — not wet enough to drip into the threads.
- Wipe once, light pressure, center out. A clean microfiber or nano cloth. No second pass with the same dirty corner.
- Finish dry with a fresh side of the cloth if a streak remains. Then leave it.
If grit is stuck after blowing, I stop and rinse the cloth, or I take a second clean cloth. I do not keep polishing. Polishing is how people turn a thumbprint into a swirl they will see forever at f/8 against the sky.
Skip shirt hems. Skip the napkin from lunch. Skip kitchen paper. Those fibers are cut for absorbency, not for soft coatings.
When I leave the filter alone
A few flecks of dust that do not show in the frame can wait until I am home. Night street light will make every particle look dramatic on the rear LCD; most of them vanish in the file. Cleaning under a street lamp with a half-dirty cloth is worse than walking another block with a speck.
Salt air is the exception. After a seaside evening I check the face before the bag closes. Salt left overnight etches. That is worth the thirty seconds.
Cloth as an add-on, not the product
The glass is the product. The wipe is maintenance.
We sell a nano cleaning cloth in small packs (5 / 15 / 25 / 40) priced from $10 to $30. It is meant to ride in the same order as a filter — not to replace the filter decision. Multilayer cloths beat paper. A fresh pack beats the one cloth that has lived in a jeans pocket for six months and collected sand.
Orders over $120 ship free on the site, so a cloth pack is an easy add when you are already sizing a UV or clear. If your bag already has a clean microfiber you trust, use that. The rule is clean fabric and no grit, not our SKU name on the tag.
Quick don'ts
- Don't dry-scrub a fingerprint.
- Don't stack dirty cloths "one more wipe."
- Don't soak the ring so fluid creeps behind the glass.
- Don't clean with the filter still hot from a car dashboard. Let it cool.
If the coating already has a permanent swirl, stop wiping. Replacement glass is the honest fix. Our clear and UV cuts exist partly so the expensive front element never becomes the thing you scrub under stress.
Blow, damp cloth if needed, light pass, done. That is the whole method.
— Leo Liang
