Both Ian Wilson and Bill Paterson have a long-standing interest in the problem of fouling and cleaning of heat transfer surfaces: fouling layers are examples of unwanted soft-solid layers and these are a major problem in many industries and universally in the food sector. This fouling problem gives rise to the cleaning challenge, particularly for the cleaning-in-place systems employed in the food and pharmaceutical sectors. The group has studied deposition and removal of several soft-solid materials on heat transfer and reactor surfaces, and developed novel techniques for studying the cleaning behaviour of these materials in situ. The technique of Fluid Dynamic Gauging, developed in the group, is now being used as a surface rheology tool. Recent work includes investigations of swelling behaviour of polymer films, attachment to nano-structured surfaces, and fouling in crude oil preheat train heat exchangers. The expertise in soft solids allows the group to consider the materials science aspects of fouling layers as part of our investigations.