Lime mortar lime putty when mixed at a 1 to 3 ratio, fill these voids to create a compact mortar. Analysis of mortar samples from historic buildings typically indicates a higher ratio of around 1 part lime to 2 part aggregate/sand was commonly used. A traditional coarse plaster mix also had horse hair added for reinforcing and control of shrinkage, important when plastering to wooden laths and for base (or dubbing) coats onto uneven surfaces such as stone walls where the mortar is often applied in thicker coats to compensate for the irregular surface levels. If shrinkage and cracking of the lime
Lime mortar needs to be performed at a time of year where the weather conditions are conducive to the mortar setting properly. Those conditions are not only above freezing temperatures but also drier seasons. To protect the slow curing mortar from damp, a siloxane can be added to the surface. With historic structures, this may be a controversial strategy as it could have a detrimental effect to the historic fabric. The presence of Portland allows for a more stable mortar. The stability and predictability make the mixed mortar more user friendly, particularly in applications where entire wall sections are being laid. Contractors