The mechanical performance of brittle structural materials, such as engineering ceramics, decreases drastically in the presence of cracks which are inevitably introduced during material preparation via machining and polishing. For functional brittle materials (glasses and semiconductors) their optical and electronic properties may also be affected by the presence of such cracks; furthermore, 'chemical damage' in the form of surface contamination may arise after polishing. We present here two contrasting methods, both utilizing the mechanical probing of a surface, to evaluate such damage.