Stormdry Repointing Additives (500 ml)

Joints should be raked out squarely to a depth of twice their width. This should result in a depth of approximately 15 – 25 mm, and never more than 35 mm. The joints should then be brushed out to ensure that the repointing mortar can form a good bond.

After shaking the bottle, Stormdry Repointing Additive No.1 should be diluted with clean tap water in the ratio 1 part Stormdry Repointing Additive No.1 to 9 parts water by volume. (Lime:sand mortars can be waterproofed using the same ratio of 1 part Stormdry Repointing Additives No.1 to 9 parts water by volume. Grade NHL 5 hydraulic lime should be used.) The resulting gauging solution should be added to the chosen sand:lime:cement mix or masonry cement/sand mix (see above) to attain workability.

To avoid shrinkage it is important to add the gauging solution carefully to ensure that only the minimum quantity necessary to attain workability is used. Once mortar has started to set and has become unworkable it should not be “knocked up” by adding more gauging solution. For this reason, only small batches of mortar should be mixed at a time.

The curing time will depend to a large extent on the chosen repointing mix (e.g. mixes containing cement will cure more quickly than those based on pure lime). During the curing period mortar should be protected from frost and should be prevented from drying out too quickly. In dry, windy or warm weather it may be necessary to spray the surface of the wall occasionally or cover the wall with damp hessian to allow a proper set, particularly where a lime mortar has been used.

To avoid shrinkage it is important to add the gauging solution carefully to ensure that only the minimum quantity necessary to attain workability is used. Once mortar has started to set and has become unworkable it should not be “knocked up” by adding more gauging solution. For this reason, only small batches of mortar should be mixed at a time.