Standardised Classifications Decorative Coatings

Standardised Classifications Decorative Coatings

Water vapour transmission rate:

sd: diffusion-equivalent air layer thickness [m] V (=WDD): water vapour transmission rate


sd [m] water vapour transmission rate V [g/m²d] ISO 7783-2
< 0.14 > 150 I (high)
0.14 - 1.4 15 - 150 II (medium)
> 1.4 < 15 III (low)

low sd-value = high water vapour permeability

Liquid water transmission rate
W: water absorption [kg/m²]
w: water absorption coefficient [kg/m²h0,5]
t: absorption time [h]

w [kg/m²h0.5] ISO 1062-3
> 0.5 I (high)
0.1 - 0.5 II (medium)
< 0.1 III (low)

low w-value = low capillary water absorption
ideal: sd < 0.14 m, w < 0.1 kg/m²h0.5

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