Application Guide
Application Guide
One Rock microcement on walls and floors — from bare substrate to a sealed, finished surface.
A starting point, not a rulebook
This guide lays out the One Rock system and the way we work — the steps, the products and the specs that matter. But microcement is a hands-on craft, and every applicator develops their own feel and style over time. Take it as a foundation to build on.
Read this first
One Rock is a thin decorative finish, not a filler. The surface — wall or floor — must be made flat, solid and movement-free before you start. Don't try to correct a poor surface by building up the microcement — get it right first, then coat it.
First things first
Safety & site protection
Set up safe, leave it cleaner than you found it.
Protect yourself
- Wear gloves when mixing and applying.
- Wear a mask — especially when sanding.
- Wear goggles to keep dust and splashes out of your eyes.
Protect the space
- Cover and protect all surfaces, fittings and furniture.
- Mask off everything you're not coating.
- Always run the orbital sander connected to a dust extractor to keep dust down.
What you'll need
Tools & materials
Have everything to hand before you start.
Application
- Metal trowel
- Flexible plastic trowel
- Drywall spatulas
- Filling knife / scraper
- Plasterer's hawk
- Bucket trowel
- Internal & external corner trowels
- Small- & medium-pile rollers & frame
- Paint tray & mixing tubs
- Drill & paddle mixer (for One Rock & pigments)
- Resin mixer attachment (to blend sealer part A & B)
- Masking tape
- Misting bottle (to close the final coat)
- Drying cloths (to dry wet tools)
- Pocket scales (for pigment)
- Heavy-duty scales (for One Rock buckets)
Sanding & finishing
- Orbital sander + dust extractor
- Detail sander or hand block for corners
- 40 grit abrasives (lowest you'll need)
- 60–80 grit abrasives
- 120 & 240 grit abrasives
- Diamond sanding discs — 50 grit (base), 100 grit (top coats); from Studio Cemento
- Vacuum cleaner
Set yourself up
Before you start
- Weigh out enough material for the job and always allow for waste — ideally 10–20%. Running short mid-wall is far worse than a little spare.
- Use pocket scales for pigment and heavy-duty scales for the One Rock itself, as the buckets are heavy.
- Tint the One Rock using the Studio Cemento pigment calculator. Our formulas are calculated in grams of pigment per kilogram of One Rock — the calculator works this out for you so the colour is accurate and repeatable batch to batch.
- Mix the pigments in small mixing cups first, adding a little water to blend the colours together, then stir that into the One Rock.
- Once pigmented, mix with a drill and paddle for a few minutes so all the pigment is fully blended through the bucket, then let it stand for a few minutes to let trapped air escape before applying.
- Surfaces must be dry, clean, solid and free from dust, grease, loose paint or movement.
- Promote airflow and allow proper drying between coats.
- Tape opposite walls, trims and adjoining surfaces so you keep a clean edge and don't drag material into finished areas.
- Clean all tools with warm water. If microcement is drying hard onto a tool, clean it with wet sandpaper.
Before microcement
Preparing the area
Build the right substrate first — microcement needs a hard, solid, stable base.
Where possible, build in cement boards rather than plasterboard, especially in showers. On floors, line ply or the existing flooring with cement board too. Fill all screw holes and board joints with flexible tile adhesive, and scrim the joints with alkali-resistant mesh tape.
Never use soft backers
Don't use foam tile backer boards or foam wet trays — they're too soft for microcement. For showers we recommend "Resin Rock" microcement-specific shower trays: resin right through, giving a solid base for the system.
Levelling uneven floors
Level uneven floors, ideally with a fibre-reinforced leveller, at 25–35 N/mm² — or higher for high-traffic and commercial areas. Check the leveller is fully cured with a moisture metre before applying the system, then lightly sand it and vacuum before priming with your chosen primer.
Get the substrate right
Surface preparation
This goes for walls and floors alike — don't coat until the surface is flat, repaired and properly sanded.
Priming by surface type
Plasterboard, skim & porous surfaces
Scrim tape all plasterboard joints. Fill joints with a flexible compound or cement-based tile adhesive, leave to dry fully, then sand flush.
Once sound and dry → prime with PRIMER
Tiles & dense non-porous surfaces
Tiles are reinforced with mesh bedded into the primer before any One Rock goes on:
- Grind the tiles to create a key and fill the joints.
- Prime with PRIMERQUARTZ (an acrylic primer loaded with aggregate) and embed fibreglass mesh, 70–100 gsm, into it — available from Studio Cemento.
- Go over the mesh with another pass of PRIMERQUARTZ to bond it to the tiles.
- Let the PRIMERQUARTZ dry fully, then apply the One Rock base coat (XL or L).
- The next day, sand off any high spots of mesh.
Wet rooms
In wet rooms, tank the corners with tanking tape, bedded in with flexible tile adhesive in a tight, thin spread. Worked thin and flat, it sits neatly under the coats to come and won't show through the finished surface.
Floors
On screeds, lightly diamond grind to remove any laitance, then vacuum thoroughly before priming. All floors are meshed into the One Rock base — either XL or L — to reinforce the system, then given a light sand once the base is down to knock back any high spots of mesh.
Floors with moisture, or prone to cracking
If there's moisture in the surface, prime with an epoxy DPM and embed mesh into it. Re-apply the epoxy DPM over the mesh and broadcast quartz sand into it while it's still wet to give a mechanical key. Let it set overnight, then vacuum off the excess quartz, sand back any high spots, and coat as normal. This is a good approach for any floor with moisture or one that's prone to cracking.
Existing cracks
Cracks that are already present can be stitched and filled with epoxy mixed with quartz sand, setting rods into the stitches to hold them. This is specialist work — contact Studio Cemento for advice on the method and the best products to use for your specific floor.
Expansion joints
Always respect existing expansion joints — best practice is to carry them through the finished floor. If a client is adamant they don't want a visible joint, the joint can be bridged and the line relocated to halfway under a doorway, but respecting it is always the safer choice.
To carry a joint through: coat the floor in the chosen One Rock system, then grind a clean line over the joint with a diamond grinder or track saw, finishing into corners with a diamond blade on a multitool. Clean the edges with 120 grit, then either leave it as an open expansion joint or fill it with a neutral-curing, colour-matched silicone — mask both sides, fill, tool the bead, and pull the tape away while it's still wet.
How the system works
The One Rock grain system
Always three coats — one base, two coloured. The grains you pick are up to you.
One Rock comes in a range of grains, from fine to very coarse: S, M, L, XL and XXL. It's applied as a three-coat system. A typical build runs:
- Coat 1 — base, untinted: XL or L.
- Coat 2 — second base, tinted: usually L.
- Coat 3 — finish, tinted: any grain — S, M, L, XL or XXL — for the texture you want.
Which grains you use is still the applicator's choice and part of your own style — this is simply the usual route.
XXL — feature walls
XXL is a very textured grain, used for feature walls where you want pronounced depth and movement in the finish.
The steps below show one common route as an example. Swap the grains to suit your system and the finish you've signed off on the sample board — but keep to three coats, with XL or L as the untinted base.
Before the first coat
Make a sample board
Always sample first — it protects you and the client.
Before starting the job, create a sample board over at least a 600 × 600 panel, built up through the same coats and grains you'll use on the wall or floor. It lets the client see the actual colour and finish in their own light, and signs off the look before any real surface is touched.
The application
Step by step
Prime the surface
PRIMER on porous · PRIMERQUARTZ on non-porous
Apply the correct primer by roller or brush. Prime the whole area evenly and let it dry before applying One Rock. The Lunik PRIMER data sheet gives a typical waiting time of at least 30 minutes under normal conditions.
Do not begin if the substrate is damp.
Base coat
Coat 1 — One Rock L or XL, untinted
With a metal trowel, apply the base coat in a thin, even coat at about 1–1.5 mm. The base is One Rock L or XL, untinted. On floors, mesh into this base coat to reinforce the system. Work cleanly section by section, tape your edges, and use corner trowels on internal and external corners.
- Don't overbuild.
- Keep the coat tight and consistent.
- On walls, sequence opposite walls so you don't damage fresh work.
Dry, sand & vacuum
After the base coat
Allow the base coat to dry 8–12 hours, ideally overnight, before sanding. Sand the area back, then vacuum all dust from the surface before the next coat.
Second base coat — tinted
Coat 2 — tinted, usually L
Mix the coloured material thoroughly first. If it hasn't been pre-tinted, tint to the chosen colour using the Studio Cemento pigment calculator so the recipe is accurate and repeatable. Apply at about 1–1.5 mm, thin and even, using a top-coat tool — a flexible trowel, plastic trowel or spatula. Again, don't use this coat to correct the surface. It should already be right.
Dry, sand & vacuum again
After the second base coat
Allow this coat to dry 8–12 hours, or until the next day. Sand with 60–80 grit using an orbital sander connected to a dust extractor, working corners and awkward areas by hand or with a detail sander. Vacuum thoroughly before the finishing coat.
Finish coat — tinted
Coat 3 — tinted finish, your chosen grain (S, M, L, XL or XXL)
Apply the finish coat thinly with a flexible trowel, plastic trowel or spatula, completing each wall or floor area fully so the finish stays consistent. Use corner trowels to keep internal and external angles crisp. If you're not happy with the result, you can sand back and recoat.
Final dry, sand & vacuum
Before sealing
Allow the final coat to dry fully. Sand with 120 grit, then vacuum for the last time so the surface is completely dust free before sealing.
Seal
Choose the right sealer for the area — see below
All One Rock finishes are sealed. The sealer you use depends on the area: Varnish W (water-based) for most walls and floors, or a harder-wearing sealer — Varnish DSV (solvent-based) or Varnish Plus (100% solids) — where there's standing water or heavy wear. Full selection guidance is in the next section.
Varnish W is a two-component, water-based polyurethane. Mix to the correct quantity and ratio using the product data sheet — the Studio Cemento sealer calculator works out the part A and part B quantities for you. The Varnish W data sheet gives a 5:1 mix ratio, recommends diluting 15–20%, applying by short-nap roller, and keeping application to a maximum of 100 g/m² per coat. Roll evenly in a cross-rolling pattern so you don't miss areas or leave roller marks.
Apply 2 coats, letting the first dry before the second. Sand lightly between coats with around 240/320 grit to smooth and key the surface, remove the dust, then apply the final coat.
Sealing in detail
Choosing your sealer
Match the sealer to the area, mix and apply each to its own data sheet.
Varnish W — water-based, two-component
A two-component, water-based aliphatic polyurethane, applied in 2 coats. Highly transparent, resists yellowing, and waterproofs the surface while staying breathable. Ideal for floors, walls, feature walls, media walls and bathrooms — not areas with standing water such as wet rooms, baths or basins.
Varnish DSV — solvent-based, two-component
A two-component, solvent-based polyurethane designed for sealing microcement, with high chemical and abrasion resistance — suited to wet and standing-water areas. Blend both components together with a drill and resin-mixer attachment at the time of use, then apply in two layers, undiluted. Available in matt or gloss, each with its own mix ratio.
Varnish Plus — single-component, 100% solids
A single-component, 100% solids aliphatic polyurethane — a very hard-wearing floor sealer for decorative and industrial flooring, spill-risk and containment areas. Doesn't yellow, interior or exterior. No part A/B and no dilution — apply in thin coats only, recoating once the previous coat is dry to the touch.
Dark colours & the harder sealers
DSV and Plus deepen darker colours — greys, blacks, pinks and so on — giving an intensified "wet look". To hold the colour true, pre-seal first (the Varnish Plus data sheet recommends a water-based primer before the final sealer to reduce this). Two routes:
- Pre-seal with Varnish W to lock in the colour and finish, then topcoat with Varnish DSV or Plus.
- Pre-seal with primer instead — in which case you'll need 2 coats of the harder sealer over it.
The Studio Cemento sealer calculators work out the part A and part B quantities for the two-component sealers — Varnish W (5:1) and Varnish DSV (3.75:1 matt or 2:1 gloss) — which are blended with a drill and resin-mixer attachment at the time of use. Varnish Plus is single-component, so there's nothing to mix. Mix only what you can use within the pot life, and contact Studio Cemento if you're unsure which sealer suits the room or how to pre-seal a particular colour.
Edges & handover
Finishing & handover
Junctions & silicone
Where microcement meets a different material — windows, furniture, trims or other surfaces — finish the join with a neutral-curing, colour-matched silicone. Where microcement meets microcement, no silicone is needed.
Before other trades come in
At the end of the job — especially on floors — let the system cure fully, the sealers in particular, before it's covered up for other trades to work over. If trades have to get in sooner, wait at least 24 hours first, then protect the surface with a breathable material.
Hand over the aftercare guide
Once the job is complete, send the client the Studio Cemento care & cleaning guide so they know how to look after their new microcement.
Conditions & good practice
Drying & curing
- Lunik drying times are based around 20°C and roughly 60% relative humidity. Colder, wetter or less ventilated conditions slow drying.
- Always apply thin coats and wait for each to dry before proceeding.
- Don't use One Rock below 0°C or above 30°C, and avoid humidity above 80%.
- The system keeps curing after application. The One Rock data sheet notes it is passable after 24 hours but continues curing for around 7 days.
At a glance
Coat schedule
| Stage | Product | Grit | Typical wait |
|---|---|---|---|
| Prime | PRIMER / PRIMERQUARTZ | — | At least 30 mins |
| Coat 1 — base | One Rock L or XL | 40 (or 50 diamond) | 8–12 hrs |
| Coat 2 — base | Tinted, usually L | 60–80 (or 100 diamond) | 8–12 hrs |
| Coat 3 — finish | Tinted, chosen grain | 120 (or 100 diamond) | Dry fully |
| Sealer 1 | W, or DSV / Plus | 240/320 before coat 2 | See data sheet / site |
| Sealer 2 | Same sealer | — | Final coat |