Janitorial & Sanitation Reference Library · Chemistry & Dilution
pH and Cleaning Chemistry
How the pH scale groups cleaning products into acids, neutrals and alkalis, which soils each removes, and which surfaces each can damage.
Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.
What it is
pH is a measure of how acidic or alkaline a water-based solution is, on a scale from 0 to 14 with 7 as neutral. The scale is logarithmic: each whole step is a tenfold change, so a pH 12 product is ten times more alkaline than a pH 11 product and a hundred times more than pH 10. Matching the pH of the cleaner to the soil is the first rule of cleaning chemistry: acids dissolve mineral soils, alkalis break down organic and greasy soils, and neutrals handle light, routine soil without harming finishes.
How to identify
- SDS Section 9 (Physical and chemical properties) lists the product's pH, often as a range for the concentrate.
- Diluted solutions move toward neutral; test strips or a pH meter show the use-solution value.
- Labels for strong acids and alkalis carry corrosive hazard statements and the corrosion pictogram.
Product families by pH
| pH zone | Family | Removes | Can damage | Typical products |
|---|---|---|---|---|
| Strongly acidic (about 0–2) | Strong acids | Heavy scale, rust, urine stone | Metals, grout, marble, limestone, skin and eyes | Some bowl cleaners, rust removers |
| Mildly acidic (about 3–6) | Mild acids | Hard-water spots, soap scum | Calcareous stone (marble, terrazzo, travertine) | Restroom and shower cleaners, descalers |
| Neutral (about 6–8) | Neutral cleaners | Light daily soil | Rarely surfaces; residue if over-concentrated | Neutral floor cleaners, damp-mop products |
| Mildly alkaline (about 8–10) | Mild alkalis | Light grease, fingerprints, body oils | Some floor finishes with repeated use | All-purpose cleaners, glass cleaners |
| Alkaline (about 10–12) | Alkaline degreasers | Heavy grease, oils, protein soils | Aluminum, some paints, floor finish | Degreasers, kitchen cleaners |
| Strongly alkaline (about 12–14) | Caustics | Carbonized grease, floor finish (by design) | Aluminum, skin and eyes, wood | Floor strippers, oven and drain cleaners |
Key points
- Ranges above are general groupings for orientation; the SDS for the specific product governs.
- Strong acids and alkalis require eye and skin protection and nearby eyewash where corrosive exposure is possible (29 CFR 1910.151(c)).
- Never mix acids and alkalis; they react and can generate heat, and acids mixed with bleach release chlorine gas.
- After using a strong alkali (such as a floor stripper), a neutralizing rinse may be needed before applying finish—follow the finish manufacturer's directions.
- Acid cleaners should not be used on marble, limestone or terrazzo unless the product says it is safe for them.
Common mistakes
- Using an acid restroom cleaner on a marble vanity.
- Degreasing aluminum with a high-pH product.
- Skipping the rinse after stripping, which leaves finish problems.
Governing standards: 29 CFR 1910.1200 (SDS Section 9 and labels); 29 CFR 1910.151(c).
Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.
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