Increased demand for high quality sheet steel in the automotive and food/beverage packaging sectors has led to adoption of the aluminium killed low carbon and ultralow carbon interstitial free grades. Unfortunately, these grades are also susceptible to unsightly surface line defects, formed by rolling elongation of non-metallic inclusions (NMIs) trapped in slabs during continuous casting operations. Oxide NMIs are the main deleterious type in formable steels. Their origins have been identified as chemical reactions between elements in the steel or physical entrainment of foreign matter. If not removed during processing of liquid steel, these NMIs may become entrapped within the cast slab. It is thus important to minimise all NMI sources during steelmaking and casting and also to optimise NMI removal from the steel bath by flotation into a covering surface slag. Many techniques currently exist to assess the resulting steel 'cleanness' and determine the surface quality of the final product. The most problematic and uncontrollable NMI source arises from casting instabilities caused by accumulation of solid masses (alumina in the case of aluminium killed steel) on the inside of refractory teeming shrouds. This 'nozzle clogging' behaviour causes undesirable in mould steel flow (entraining mould slag into the slabs) and, in extreme cases, may even result in premature termination of casting. Proposed clogging mechanisms include deposition of NMIs from the bath, premature steel solidification, and refractory -steel chemical interactions. Over the past 20 years, many process improvements have been introduced to minimise nozzle clogging and improve steel cleanness. Ladle and tundish metallurgy, mould technologies, and alternate caster configurations have all played important roles. Inclusion engineering by calcium treatment has also proved successful, but is an expensive and difficult technique. Possibly the best solution to date has involved changing the design/composition of the clog susceptible refractory itself. However, variable performance and high purchase cost have prevented widespread industrial adoption of these anticlogging innovations. If such issues can be addressed through further research, there should be no reason why formable sheet steel cannot meet customer quality requirements and maintain its dominant share of the autobody and food/beverage can markets. MST/5166At the time the review was written, the author was undertaking doctoral studies in the EPSRC Engineering Doctorate Centre in Steel Technology run by the