Repointing Brick: The Purpose
The process of repointing brick involves the renewal of mortar in the bedding and face joints of brickwork. Its purpose is to replace decayed and worn-out mortar with a fresh batch, giving it a new water repellent surface. There is considerable skill involved in the repointing process because great care has to be taken not to damage the bricks or the non-decayed mortar. Depending on the type of brick used, the process is carried out with the help of special repointing tools or, in some cases, by hand.
Repointing Brick: The Preparation
The two steps of preparation are the joints themselves, and the mortar that goes into them. Decayed and crumbling mortar is usually removed completely, usually to a depth equal to the width of the joint. Older brickwork may need more mortar removed, but typically the limit is two and a half times the width of the joint. Under that will be sound mortar that doesn't need replacing. Once the first preparation stage is complete, the mortar needs to be mixed. Careful attention should be given to the composition, texture and color of the new mortar so that the finished brickwork doesn't have patches of different mortars. Once these two steps are complete, the repointing can begin.
Repointing Brick: The Process
Wet the surfaces between the joints so that they are damp but not soaked. This will allow for better adhesion between the mortar and the bricks. Next, the mortar is applied in layers with a pointing trowel, similar to a brick trowel but smaller and narrower. The point of applying it in layers is to allow the mortar to cure properly, ensuring maximum adhesion and water-tightness. When the mortaring reaches the surface of the joint, it is smoothened and given a finish profile. This is also called tooling the joint. This needs to be done with the finish of the existing mortar in mind, and the match needs to be perfect.
Repointing Brick: Tools
Apart from materials like cement mix for the mortar and the basic mortaring accessories, there are some specific tools required. The pointing trowel is designed for this purpose, as are slickers for tooling the joints, rakes for removing old mortar, and special foxtail brushes for cleaning the masonry after the job is done. These tools are all part of a master mason's essentials, and are usually treated with the utmost care and respect. After all, a craftsman's work can only be as good as the tools at his disposal.
Repointing Brick: Tips
When repointing brick, there are some things you can do to make the work easier. For example if you're working on narrow joints and you don't want any mortar on the adjoining bricks, you can mask off those parts with tape. This will give you more freedom when pointing those particular joints. Another example is the improper levelling of the mortar in line with, or below the level of the brick. If this is not done correctly, several things can happen. First, when it rains, water will collect at the mortar joints and penetrate the cracks between the brick and mortar. Second, the mortar that is out of alignment with the surface will wear out quickly and will need to be replaced sooner than usual. Third, the smudging of mortar on the brick surface will give a shabby appearance to the brickwork.
Repointing Brick: Technique
It is absolutely fascinating to watch a professional bricklayer repointing brickwork. The fluid movements that are characteristic of an expert engrossed in their work are reminiscent of a Samurai warrior doing his Kata exercises, all the grace and poise of the world at his disposal. The immense concentration that this calls for needs to be developed over years of hard practice and training, and experience. The master mason's flowing hand movements come from years of practice and are second nature to him. If you break down the actions into specific motions, you will find that the techniques for each step inherently exhibit economy of energy and effectiveness of effort. You may not think that a simple bricklayer's job of replacing old mortar is glamorous or engaging, but tell that to a master craftsman and he'll probably just give you a gentle smile and say, "hey, whatever", because he knows better.