Done properly lime pointing can last hundreds of years and prevent the wall from movement and plants growing inside it. A fat lime putty from slaked lime can be used. Different coloured stone and sand can be incorperated to match previous stone or mortar. Usuially we use a Nhl 3.5 mortar and mixed sharp sands that set relitavly quickly and allow for a shorter period of protection providing continual dampness and shade from the sun. This aids the set and reaction with air and moisture called carbonation which continues allowing the wall to dry and breath easily.
Lime Pointing a wall in Bath
This wall was pointed using a pre mix of bath stone coloured fat lime putty with the additive of some NHl 3.5 to aid the set. Some of the old stron mortar was left to save on time and money. In the base layer a small amount of white cement was used for longevity as it can be a continual wet area for long periods.