Technology
What hard water is
10 minEstimated reading time — roughly how many minutes it takes to read at a normal screen pace.
It is elevated Ca²⁺ and Mg²⁺ (and other ions). After water evaporates on the body, crystalline rings remain — water spots. In sun, droplets dry faster and locally a more aggressive chemical environment can form than with
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What hard water is
It is elevated Ca²⁺ and Mg²⁺ (and other ions). After water evaporates on the body, crystalline rings remain — water spots. In sun, droplets dry faster and locally a more aggressive chemical environment can form than with “pure” water.
Interactive diagram
Hard water and drying speed
The slider simulates water hardness and how long water stays on the paint as isolated droplets — further right = worse water spot scenario.
Medium load
Drops partially mineralize before evaporating — systematic drying and a drying aid help significantly.
Rings = mineral residue after evaporation
Regional reality in the Czech Republic
Water hardness varies by water utility and source. In general: tap water for washing is not demineralised — expect mineral content unless you work with RO/DI water.
Typical ranges in Czech public supply (indicative):
| Hardness (°dH German) | Approx. mg CaCO₃/L | Common regions / note |
|---|---|---|
| Soft (< 8 °dH) | < 140 | Some mountain / surface sources |
| Medium (8–14 °dH) | 140–250 | Large share of distribution networks |
| Hard (> 14 °dH) | > 250 | Limestone aquifers, many small supplies |
Exact values for your postcode: annual water-quality report from your supplier (zpráva o jakosti pitné vody). For detailing, assume medium to hard unless you filter.
Prevention during washing
- Do not leave the vehicle in direct sun with droplets on the paint.
- After rinse, start drying immediately — see Drying, drying aid, and Water Spot Remover.
- Shade, morning / evening hours, or filtration (RO/DI) for final rinse in studio workflow.
What water spots do to hydrophobicity
Minerals can fill micropores in ceramic — beading appears lost visually. An acid phase in the studio sometimes helps; home acid experiments are not safe.
Summary
| Steps | Purpose |
|---|---|
| Shade / cool panel | slows droplet drying |
| Quality drying | removes water before mineralisation |
| RO/DI final rinse | optional maximum for detailing |
Topic: Prep & washing
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