Wattle & Daub: Craft, Conservation & Wiltshire Case Study
3.6 Daub
4.1 Soils
4.1.3 Strength
4.2 Dung
4.2.2 Lignin
4.2.3 Urine
4.3 Fibre
5.4.2 Renewal

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4.1.3 Strength

A weak daub may fail if it has insufficient cohesive strength to prevent it delaminating from the wattle or from failure within the body of the clay. In a vertical panel the critical stress is shear. The strength of a soil sample can be measured in the laboratory using either the vane method or small shear box.[56] After application, a daub is not under a compressive load and will therefore fail in shear if its ‘apparent cohesion’ is exceeded.[57]

[56] BS1377-7:1990.
[57] The apparent cohesion can be determined as the y-intercept from a graph of peak strength versus normal (compressive) stress.