Applying Primer 100 & Fibreglass Mesh

Surface Prep

Before you prime and mesh it’s essential that your surface is completely flat, dry and well-consolidated, so that there is no chance of movement.  Use a small amount of Joint Filler or a filler that is suitable for the substrate, to flush out joins and counter-sunk screwholes. Then sand until the surface is completely flat.  See surface prep for full details of preparing surfaces for microcement.

Applying Primer 100 & Fibreglass Mesh

Fibreglass mesh adds strength to your microcement and adds strength to the substrate. Cut the mesh to size & then flip it over so that it curls towards the surface. You might find it easier to use Self Adhesive Fibreglass Mesh on corners.

Use a medium pile roller to apply an even coat of primer to the surface and mesh.

The primer should help to hold the mesh in place, but thats not it’s primary purpose, it’s more important to get full, even coverage over the area. If the mesh isn’t sticking, then use stainless steel staples to hold it in place instead.

Primer 100 is a thick, high-quality product.  To get the full consumption out of the bottle, you may need a little water.  Add up to 10% water & shake to get all of the primer out of the container.

Highly Absorbent Surfaces, Like Fresh Plaster & Concrete

On highly absorbent surfaces, like freshly laid concrete or fresh plaster, use Primer 100 mixed with water at a ratio of 50:50 before applying a neat coat. Similar to a mist coat of paint, this will prevent the primer from sitting on the surface and create a strong bond between surface and microcement. The primer needs to sink into the substrate to take hold, which is where the water comes in.

After around 1 hour it should be dry enough to take a neat coat of Primer 100. If the substrate is very absorbent, you might need extra primer to complete this stage.

Leave to Dry

Leave the primer to dry. This should take around 1 hour. Primer 100 will lose it’s tack after 12 hours, so you will need to make sure you apply the 1st base coat within 12 hours or apply another coat of Primer 100 when you are ready to start the base coats.

When to Choose High Performance Primer

We highly recommend that you choose this option if you are working on load-bearing horizontal surfaces that have joins e.g. OSB/Ply/MDF/Cement Board flooring, or across transitions between shower trays and surrounding floors. It also helps to strengthen concrete surfaces that have cracked, however the cracks should be repaired in advance. It’s also useful for bridging joins between boards in furniture and worktops.

This primer also helps to inhibit moisture and stains from transferring through from your substrate.

If you think you need High Performance Primer but haven’t got it in your kit, the products are also available to buy separately.