How to Apply Refractory Mortar

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Things You'll Need

  • Rubber or leather gloves

  • Refractory mortar

  • Wooden stick

  • Margin trowel

  • Bricks

  • Ruler

  • Brick hammer or rubber mallet

  • Professional cellulose tiler sponge

  • Water

  • Bucket

  • Ceramic wool (if needed)

Refractory mortar is often found in fireplace brickwork.

Refractory cement is often used for laying brickwork in high-temperature environments such as fireplaces. Refractory mortar mix consists of Portland cement, silica sand, perlite and fireclay. Although the bricklaying technique used for refractory mortar resembles the popularly used Portland cement-laying technique, you should allow the refractory cement to dry completely before exposing it to high temperatures. Once this mixture is dried thoroughly, it should be able to withstand years of high heat exposure.


Step 1

Clean the area in which you intend to lay bricks. Sweep the area and wash it thoroughly with water. Allow the surface to dry completely.

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Step 2

Open the refractory mortar bucket and aggressively stir the contents with a wooden stir stick or a trowel. The mixture may settle or separate during storage and shipment, so it is vital that you thoroughly stir the mixture to bring it back to a suitable state.


Step 3

Use a margin trowel to apply a layer of mortar to your dry brick. As a general rule, while doing brickwork you should apply the mortar directly to the brick, not the work surface. You can also dip the working edge of your brick into the mixture, if you prefer; just make sure the entire edge gets covered.


Step 4

Immediately place the brick into place on your work surface. Push down and make sure that the brick gets a good bond on the surface on which it was laid. Mortar should squeeze out of the crack as it is laid and pushed into place. The joints between bricks should be around 1 mm and never larger than 3 mm wide.


Step 5

Scrape excess mortar off the edges with your trowel and place the mortar back in the bucket.

Step 6

Grab your next brick. Cover the bottom edge with mortar in the same manner, as well as the side edge that will be touching the first brick you laid. Push it into place until it gets a good bond. Repeat this process until you have completed your first row.


Step 7

Check the first row with a level to ensure that it is level. If the bricks need adjusting, use a brick hammer or a rubber mallet to tap them into place.

Step 8

Use a slightly moistened professional cellulose tiler sponge to clean the brick area as you work. This will keep the area clean, remove excessive mortar from the joint areas and eliminate any rogue mortar that has been misplaced on your work surface. Rinse the sponge in a bucket of water often and ring out any excess water.


Step 9

Continue laying subsequent layers of brick until you have reached your desired size and shape.

Step 10

Place quarter-sized amounts of refractory mortar along the edge of your work surface if you are applying ceramic wool to the brickwork. Working from one end, apply medium pressure on the mortar areas as you position the wool into place.


Always wear gloves when working with refractory mortar, as the mixture can harm your skin. Wipe your tools clean frequently, especially if you are taking a break or mortar is drying on the surface of your tools. Thoroughly clean the tools at the end of the project. Always place your trowel in the mortar bucket, on the bricks or in the sponge bucket to keep it from picking up unwanted dirt or debris.



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