The present invention provides a testing substrate (W) for estimating stress in production substrates due to a substrate support, said testing substrate having a support surface (SS) divided into predefined portions, wherein the predefined portions comprise at least one first portion (1) having a first coefficient of friction being substantially uniform across the at least one first portion, and at least one second portion (2) having a second coefficient of friction being substantially uniform across the at least one second portion, wherein the second coefficient of friction is different to the first coefficient of friction. The present invention also provides a method for estimating stress in a substrate due to a substrate support and a system for making such an estimation.