To avoid warping, the carpets are stretched in a frame and dried.
In professional carpet washing, this procedure is mandatory to avoid warping when drying. The effect is known from most textiles, but it is much more pronounced with the dimensions of a carpet.
The individual carpets are fixed on large wooden plates and dry in their shape for at least 48 hours.
The long side edges are sometimes sewn with a leather border for stabilization on the back.