Applying Primer 100 & Fibreglass Mesh

Follow the directions below to apply Primer 100 & Fibreglass Mesh to you substrate to prepare and strengthen it for Microcement.

The standard consumption for Primer 100 is 1l per 10m2.  Expected drying time for Primer 100 is 1 hour and you will need to apply the 1st coat of base within 12 hours.

You will need a knife to cut the mesh and a medium pile roller & tray to apply the Primer.

Choose Primer 100 for Absorbent Surfaces

Make sure you have chosen the right primer for the surface or “substrate” that you will be applying the microcement to. Primer 100 is the primer to use on Absorbent substrates.  Absorbent substrates include plaster, concrete, screeds, cement board. Aqua4ma and composite timbers.

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 the base coat or a suitable filler to flush out joins and counter-sunk screw holes and sand until the surface is completely flat.  See surface prep for full details of preparing surface for microcement.

Applying Primer 100 & Fibreglass Mesh

Fibreglass mesh adds strength to your microcement and adds strength to joins in 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.

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 you can also use stainless steel staples to hold it down.

Try to get the mesh flat to the surface.  If you do get bubbles in the mesh that you can’t flatten, you might need to move on and deal with them when applying base coats by slashing the bubble with your trowel or utility knife and flattening down at that point. If bubbles in the mesh are still showing through after the 2nd base coat, sand them out so that you have a completely flat surface before applying top coats.

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.

Fresh Plaster & Concrete

On freshly laid concrete, screed, self-leveller 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 to buy more Primer to complete this stage.

Leave to Dry

Leave the primer to dry. This should take around 1 hour. Primer 100 will loose it’s tack after 12 hours, so you will need to make sure you apply your base coat within 12 hours or apply another coat of re-prime.

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 using a concrete crack repair kit. It’s also useful for bridging joins between boards in furniture and worktops.

This primer 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 in our floor strengthening kit.