Pro edition
Hard-Water Guide
The most-argued-about job in this trade. A customer pays to have mineral staining removed, it does not come off, and both sides think they are right — because the answer depends on whether the mineral sits on the glass or has etched into it. That is testable in about a minute.
The four stages
| Stage | How it looks | Outcome | Cost |
|---|---|---|---|
| Stage 1 — surface deposit | Wipes to a smear with vinegar on a cloth; the smear clears. | Polishes out fully. | $8 – $20 per pane |
| Stage 2 — bonded scale | Vinegar dulls it but a chalky bloom stays. Fingernail catches slightly. | Usually polishes out. Takes three to four times as long. | $25 – $50 per pane |
| Stage 3 — early etch | Nail catches clearly. Wet glass looks clean; dry glass shows the pattern again. | Partial improvement only. We will show you one pane before quoting the rest. | $40 – $75 per pane |
| Stage 4 — full etch | Visible pitting under raking light. Wetting the glass changes nothing. | Nothing removes this. The glass is the damage. | Replacement, not cleaning |
The one-minute test
- Wet a small square with white vinegar and leave it 60 seconds
- Wipe with a clean microfibre and let it dry fully
- Look across the glass at a low angle, with light behind it
- Run a fingernail over the boundary between treated and untreated
- If the treated square is clear, it is stage 1–2. If the pattern returns as it dries, it is stage 3+
What causes it
- Irrigation overspray
- The single biggest cause we see. A head aimed a few inches high will etch a ground-floor pane in three summers.
- Salt spray left through a season
- Coastal glass that goes a full year between cleans starts bonding.
- Concrete and stucco runoff
- Alkaline, and far more aggressive than tap water. New builds are the usual victims.
- Pressure washing the siding
- Drives mineral-laden water onto glass and then dries it in the sun. Cover the windows first.
Preventing it
- Re-aim sprinkler heads away from glass — the cheapest fix in this entire guide
- Do not let coastal glass go more than five months in summer
- Rinse windows before washing the siding, and rinse again after
- Squeegee shower glass; the same chemistry, in miniature, every day
- Ask about a sacrificial coating on west-facing panes if irrigation cannot be moved