How to apply microtopping, step by step

Yellostone microtopping, often called microcement, is ready to use: no powder to mix, and it does not dry out in the tub, so you have time to work. A careful DIYer can apply it themselves. This guide follows our application datasheet, which you can download from the kit page.

Before you start

• Do a test on a board or a sample: you will get your technique right before the real job.
• Ventilate or heat: a fan or a site heater speeds up the drying of the microtopping and the varnish.
• Allow the time: 4 to 5 days to apply, then 7 days before normal use.

The equipment

• A sander, abrasives in 40/60, 60 and 120 grit, and a vacuum cleaner.
• A roller for the primer and the varnish.
• A trowel or a spatula for the two A coats.
• A plastic smoothing spatula for the B coat.
• A paint mixer to blend the varnish with its hardener.

1. Prepare the substrate

Sand the substrate with 60 grit, then vacuum. Over tiles, first fill the grout lines with a skim to zero, using a ready-to-use tile adhesive: otherwise they show through (see microtopping over tiles). On underfloor heating, switch the screed on for 24 h before you start.

2. Apply the primer

Roll on the bonding primer at 100 to 120 g per m². It dries in 2 to 8 h depending on the substrate.

3. First A coat

Mix the A tubs to even out the texture and the colour. Spread about half of the A tubs with a trowel or a spatula, 1 mm thick (about 1 kg/m²). This coat does not affect the final look. It hardens in 2 to 6 h: a visual check is enough.

Then lightly sand with 40/60 grit, just to knock off any excessive ridges, and vacuum.

4. Second A coat

Apply the rest of the A tubs with random strokes, aiming for a fairly smooth result. This stroke creates the final effect: grained, shaded or more textured. Sand as for the first coat, keeping slight reliefs: heavy sanding wipes out the material effects.

5. The B coat, the finish

Mix the B tubs; if the product is too thick, add a little water. Work it with a plastic smoothing spatula, pressing and scraping the coat to fill the hollows left by the A coat. After 12 to 24 h of drying, sand lightly with 120 grit, then vacuum thoroughly.

Wait 24 h before applying the varnish.

6. Two coats of varnish

Filter the varnish, then mix it with its pre-measured hardener for 1 minute with the mixer: a poorly blended mix is less resistant. The mix must be used within 30 minutes.

• Matt finish: two coats by roller, 3 to 24 h apart. The milky look disappears as it dries; even out any white overlaps.
• Satin finish: one impregnation coat, on a floor above 12 °C, then the satin varnish the same day, 1 to 4 h later. A second coat of varnish is recommended in a shower or on a worktop.

Drying

After 24 h, the microtopping is still fragile: it hardens in contact with the air for at least 7 days.

• Do not cover the surface (tarpaulin, cardboard) while it dries.
• Do not walk on it or put anything on it for 3 to 4 days.
• No water for 3 days.
• Hardening is complete after 7 days at 20 °C.

Mistakes to avoid

• Sanding too fine between the A coats: a fine abrasive "burns" the surface and darkens the shade.
• A stainless steel trowel for the B coat: it leaves grey marks.
• Poor vacuuming before the varnish: a grain of sand leaves a tiny hole at the slightest wear.
• Varnishing too early: wait 24 h after the B coat.

Getting help

To get a feel for it, we offer training courses. Your stockist will help you plan the job. For a walk-in shower, a trained applicator is recommended.

Frequently asked questions