Eighteenth-century chemists could gain useful income and patronage as advisors to industry – and some of the wealthiest and most influential industrialists were brewers. Making chemical knowledge credible to this audience, however, was not always easy: most brewers trusted the direct lessons of the brewhouse – and also the counting-house – to those of the laboratory. This talk discusses how chemists tried to resolve these problems, and how they were challenged by experienced brewers promoting a scientific identity of their own.