waterafstotend

Waterafstotend describes the property of a material or surface that resists wetting by water. When a waterafstotende surface is contacted by a water droplet, the droplet tends to bead up and roll off rather than spread out. This is different from being waterproof, which implies impermeability to water under pressure; a waterafstotende surface may still allow water to penetrate under certain conditions or pressures.

The degree of water repellency is commonly described by the contact angle between water and the surface. Surfaces with contact angles greater than 90 degrees are considered hydrophobic, while highly water-repellent or superhydrophobic surfaces have contact angles above about 150 degrees and often exhibit low roll-off angles.

Waterafstotend behavior can arise from chemical properties, such as low surface energy materials (for example, certain fluorinated polymers or silicones), and/or from surface roughness at micro- and nano-scales. In many cases, a combination of low surface energy and roughness creates a Cassie-Baxter state, where air pockets under the droplet reduce contact and enable self-cleaning effects.

Applications include textiles and outdoor gear, construction materials like water-repellent concrete and wood coatings, glass and ceramic treatments, and protective coatings for electronics. Durability varies: some coatings are temporary and require reapplication, while others are designed for long-lasting performance. Environmental considerations are relevant, as some water-repellent chemicals have raised concerns and regulatory attention.

Evaluation of waterafstotend properties typically involves static contact angle measurements and roll-off or tilt tests, along with standardized spray or rain tests in industrial settings to assess performance under real-world conditions.