How to Dissolve Lime Mortar

Lead Image
  • 2-3 hours
  • Beginner
  • 25-60
What You'll Need
Muriatic acid
Protective clothing
Trowel or putty knife
Plastic container

Lime mortar is used in a variety of ways, especially in brickwork. If some of the extra lime mortar needs to be removed, the easiest way is to scrape it off using a metal putty knife, a trowel, or a spade. However, some of the mortar may still cling on to the brick or to the material it has been used for. Another way to do it is to dissolve it using acids. However, using acids to dissolve mortar can be quite tricky. Although vinegar can dissolve the mortar to some degree, it may not be the best solution. Below is a set of instructions to dissolve lime mortar using muriatic acid.

Step 1 – Scrape the Excess Mortar

To make the dissolving process a lot easier and faster, make sure to scrape off the larger portion of the mortar using a trowel or a putty knife. This way, you do not need to use a lot of acids to dissolve the mortar. Clean the residue afterward.

Step 2 – Safety Preparations

Muriatic acid is a very strong acid and therefore requires careful safety preparation. Make sure to wear gloves and protective clothing to protect the skin from direct contact. A muriatic acid is a form of hydrochloric acid and it can burn the skin instantly. Use protective glasses as well just in case.

Step 3 – Mix the Acid Solution

The safest way to use muriatic acid is to weaken it with water to come up with a ten percent solution or less. Mix one part of the acid to nine or ten parts of water. Make sure to mix them well in a plastic container. Metal containers can be corroded. Never ever apply the acid directly on the mortar. Make sure to weaken it first.

Step 4 – Prep the Lime Mortar

Do not directly apply the acid solution to dry mortar. Wet the mortar first with water and allow the excess water to escape for a couple of minutes. In addition, do not apply the solution to a newly applied mortar. Give it at least two weeks to cure, unless working with already cured mortar.

Step 5 – Apply the Acid Solution

The solution can be applied to the lime mortar in a number of ways. It can be sprayed onto the lime mortar using a plastic spray bottle, poured directly, or in any other way possible. When the solution is applied to the mortar, allow it to sit there for about ten minutes or so until it dissolves the material. Notice that there are bubbles formed during application. This means that the solution is doing its work.

After ten minutes or so, remove the dissolved mortar using a scrub or a brush. Never allow the acid to stay on the surface for a long time. Rinse the acid well with water after the dissolved lime mortar has been removed.