Understanding pH values
The pH value shows whether a liquid is acidic, neutral or alkaline. In cleaning, this is important because the pH value determines which type of dirt is removed and which materials react sensitively. Here we explain the topic in a simple and 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 further away from 7, the stronger the effect, but also the higher the risk for sensitive materials.
pH scale at a glance
Note: The colours are for orientation. In practice, colour display may vary depending on the indicator.
How is the pH value measured
In practice, the pH value is measured with indicator paper, indicator solutions or an electrode (pH meter).
- Briefly dip the indicator paper into the liquid.
- Compare the colour with the scale.
- A rough classification is usually sufficient for everyday use.
Universal indicators often show: acidic yellow to red, neutral yellow-green, alkaline green to blue.
Which pH value helps with which type of dirt
| Cleaner type | pH range (approx.) | Typical effect | Typical application |
|---|---|---|---|
| Acidic | 1 to 6 | Limescale, urine scale, early rust, mineral deposits | Bathroom, toilet, taps, shower walls, descaling |
| Neutral | 6 to 8 | Gentle cleaning, light dirt film | Everyday use, sensitive surfaces, maintenance cleaning |
| Alkaline | 8 to 14 | Grease, protein, dirt film, heavy soiling | Kitchen, industry, workshop, heavy floor soiling |
Material compatibility: where caution is needed
Not every cleaner is suitable for every material. Especially with natural stone, metals and coated surfaces, incorrect pH values can cause damage.
Acidic cleaners are often not suitable for
- Limestone-based stones such as marble (may become dull or etch)
- enamelled surfaces (risk depending on condition and contact time)
- aluminium and sensitive, coloured plastic surfaces
- grout and sensitive tap finishes if too strong or left too long
- PVC and clinker depending on the surface and product, so always test first
Basic rule: never use acidic products on limestone-based natural stone. If unsure, test in an inconspicuous area first.
Strongly alkaline cleaners are often not suitable for
- linoleum and rubber flooring
- care films and painted surfaces (can dissolve coatings)
- polished limestone-based stones (surface may be attacked)
- aluminium (corrosion or discolouration possible)
Basic rule: use strongly alkaline products only 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: allow a short contact time; do not let it dry.
- Mechanical action: support with a cloth, sponge or brush instead of relying on chemistry alone.
- Rinse: with strong cleaners, neutralise with water and remove residues.
Frequently asked questions
If you tell us which surface you want to clean and what kind of soiling it is, we will recommend the right cleaner and the correct application.
