Almost all buildings built before 1900 used lime based mortars, plasters and renders (with NO cement) and these should always be used for any work on pre-1900 buildings. However the ecological, energy efficient and aesthetic qualities of lime mortars are also making them attractive for new-build applications. If you wish to make up your own plaster or mortar, the Old House Store supplies a wide range of products. Alternatively, their Lime Plaster and Mortar Mixes category contains ready-mixes, including Non Hydraulic and Hydraulic Limes. If you are unsure what to order, this website contains a wealth of advice, including a guide to choosing the right lime mix, coverage rates and technical information.