The fouling caused by a refinery feedstock on one or more refinery processes, said process comprising: (i) providing a plurality of refinery feedstocks and/or a plurality of fractions of one or more refinery feedstocks, (ii) providing an array comprising a plurality of metal samples representative of metallurgy present in a refinery, (iii) contacting each of the plurality of metal samples with oneor more of said (iv) refinery feedstocks or fractions under non-static conditions, and determining the fouling of said refinery feedstock or fraction thereof. Preferably, the metal samples are in theform of a microfabricated array and the testing is carried out in parallel using high throughput experimentation.