Transparent high lead and tin-opacijied lead-alkali glazes have been extensively used throughout Europe and the Near East from theirjrst appearance in the Roman era and the tenth-to eleventh-century Islamic world, respectively, up until the present day. Using, to a large extent, information which is widely scattered through a diverse range of literature, the methods employed in the production of these two glaze types arejrst outlined and their merits are then compared with those of alkali glazes in terms of ease of preparation of the glaze mixture, ease of application of the glaze, ease ofjring, cost of production, glaze-body j t and visual appearance. The principal advantages of transparent high lead glazes as compared to alkali glazes are shown to be ease ofpreparation and application of the glaze suspension, low susceptibility to glaze 'crazing' and 'crawling' and high optical brilliance. Factors that influence the choice of tin-opacijied lead-alkali glazes include ease of production of tin oxide by melting tin and lead metals together; a reduced risk of reduction of lead oxide to lead metal and consequent blackening of the glaze; and, again, low susceptibility to 'crazing' and 'crawling'. Limits of current knowledge regarding these two glaze types and requirements for future research are outlined.

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A multidisciplinary programme of research on the glazed ceramics of the Islamic world has been focused on questions of their dating, provenance and technology. One particular question has been the development of tin‐opacified glazes, and the nature of glaze opacification generally in the Islamic world. The findings of the various studies combine to indicate that tin was first used experimentally in Basra, Iraq, in the first half of the eighth century AD, apparently within the context of pre‐Islamic opaque‐glaze technology. Over the course of the next century, an opaque‐glaze technology entirely reliant on tin oxide inclusions was developed in Iraq and Egypt and, subsequently, this technology spread to the rest of the Islamic world and also to Europe.