Understanding pH Values
The pH value shows whether a liquid is acidic, neutral or alkaline. In cleaning, this is important because the pH level determines which type of dirt is removed and which materials may react sensitively. Here we explain it in a simple, practical way.
What is the pH value
The pH value is a scale from 0 to 14 and describes how acidic or alkaline a liquid is.
- pH 0 to 6 means acidic.
- pH 7 means neutral (like pure water).
- pH 8 to 14 means alkaline (basic).
The pH scale at a glance
Note: The colours are for guidance only. In practice, the colour may vary depending on the indicator.
How is the pH value measured
In practice, the pH value is measured using indicator paper, indicator solutions or a measuring electrode (pH meter).
- Dip the indicator paper briefly into the liquid.
- Compare the colour with the scale.
- An approximate result is usually enough for everyday use.
Universal indicators often show: acidic = yellow to red, neutral = yellow-green, alkaline = green to blue.
Which pH level helps with which type of dirt
| Cleaner type | pH range (approx.) | Typical effect | Typical use |
|---|---|---|---|
| Acidic | 1 to 6 | Limescale, urine scale, rust marks, mineral deposits | Bathroom, toilet, taps, shower screens, descaling |
| Neutral | 6 to 8 | Gentle cleaning, light dirt film | Everyday cleaning, delicate surfaces, maintenance cleaning |
| Alkaline | 8 to 14 | Grease, protein residues, dirt film, heavy soiling | Kitchen, industry, workshop, heavily soiled floors |
Material compatibility: where you need to be careful
Not every cleaner is suitable for every material. Especially with natural stone, metals and coated surfaces, the wrong pH level can cause damage.
Acidic cleaners are often not suitable for
- Limestone-based stones such as marble (can become dull or etched)
- Enamelled surfaces (risk depends on condition and contact time)
- Aluminium and sensitive coloured plastic surfaces
- Delicate fittings surfaces (bronze, copper etc.) if too strong or left on for too long
- PVC and clinker depending on surface and product – always test first
Basic rule: never use acidic products on limestone-based natural stone. If unsure, test on an inconspicuous area first.
Strong alkaline cleaners are often not suitable for
- Linoleum and rubber flooring
- Care films and painted surfaces (can dissolve coatings)
- Polished limestone-based stones (surface can be attacked)
- Aluminium (corrosion or discolouration possible)
Basic rule: only use strong alkaline products if the material and coating are suitable.
How to avoid common mistakes
- Test first: check in an inconspicuous area whether the material reacts.
- Use the right dosage: stronger is not automatically better.
- Contact time: let it work briefly, do not let it dry.
- Mechanical action: support with a cloth, sponge or brush instead of relying on chemicals alone.
- Rinse afterwards: neutralise strong cleaners with water and remove residues.
