Clean Freaks Co. Skylight cleaning in Los Altos Hills.

On a Los Altos Hills lot, a skylight sits under a working canopy. Coast live oak and valley oak shed catkins in spring, drop tannin-heavy leaves and acorns through fall, and rain washes that debris down a pitched roof toward the one flat obstruction on it — the skylight curb. What settles there is not ordinary dust. Oak tannins bleed a rust-brown stain into glazing and into the sealant bead around the frame, and left through a wet winter that staining sets rather than rinses off.

The mid-Peninsula climate compounds it. Nights here draw marine fog off the coast, and that moisture evaporates on the glass and leaves a mineral film that reads as permanent haze, dulling the daylight the skylight was installed to deliver. North-facing and shaded panes stay damp long enough to grow a green-black biofilm in the corners, and the same runoff that a graded hillside lot is engineered to shed keeps the low edge of the glazing perpetually wet.

The assembly itself sets the constraints. A flat glass unit, a curb-mounted acrylic dome, and a deck-mounted laminated pane each take a different touch, and none forgive an abrasive pad or a high-alkaline degreaser near the gasket. Reaching them means working above a pitched roof on a hillside grade, over glazing that must stay watertight when the rains return — not a job that belongs on a ladder and a squeegee.

1. The partner first identifies the glazing — tempered or laminated flat glass, or an acrylic dome — because acrylic scratches under a blade and hazes under solvents that flat glass tolerates, so the pad, blade, and chemistry are chosen to the material before anything touches it.
2. Oak tannin staining and catkin litter are cleared from the curb and the sealant bead by hand, then treated with a dwell rather than scrubbed, so the brown stain lifts out of the glazing and the gasket without disturbing the watertight seal the assembly depends on.
3. Marine-fog mineral haze is broken with a mild acidic dilution and a purified-water rinse that dries without spotting, restoring the daylight transmission the skylight was installed to deliver, while shaded-pane biofilm in the corners is removed and the surface left clean enough to slow its return through the next damp season.
4. Roof access over the hillside grade is planned first — anchor points, runoff paths, and footing on the pitch — and the flashing, curb, and gasket are checked as the glass is cleaned, so a developing leak or a failing sealant bead is flagged and reported before the wet season finds it.

• Late spring, after the oak catkins finish dropping (typically May), when the pollen and spent catkins have settled onto the glazing and curb but before summer bakes them into a stain.
• Early fall, ahead of the November rains — clearing leaf litter and tannin off the curb before the wet season sets it, and confirming the flashing and gasket are sound before runoff tests them.
• After a stretch of heavy marine fog, when the panes have hazed over and daylight through the skylight has visibly dulled.
• At the end of the wet winter (March into April), to lift the biofilm that took hold in the shaded corners over months of damp, north-facing exposure.
• Before hosting, when overhead glass sits directly in the sightline of a room and the haze reads under interior light.