Microcement isn't waterproof on its own. The cement-based base coats are absorbent, so every microcement floor or wall needs a sealing system on top of it: a primer coat followed by a protective topcoat that lets it handle water, cleaning chemicals, and everyday wear. Ecoflor's sealing system pairs Prymaren, a water-based acrylic primer, with Ecostar 2K HD, a two-component polyurethane lacquer, and that combination is what actually makes a microcement surface waterproof, washable, and durable rather than just decorative.

Why Microcement Needs a Sealer

Uncoated microcement absorbs water, oil, and staining agents the same way any cement-based surface does. Left unsealed, it will mark permanently the first time coffee, wine, or shower water sits on it, and it has no meaningful resistance to cleaning chemicals. The sealer is what converts a porous mineral surface into one that's washable, water-resistant, and safe for wet areas. It's not an optional finishing touch, it's the layer that makes the floor or wall functional.

The Two-Part System: Primer, Then Topcoat

Prymaren goes down first. It's a single-component, water-based acrylic primer formulated specifically for microcement, using non-yellowing resins so it doesn't discolour light-coloured finishes over time. Its job is to bind to the mineral substrate and give the topcoat something reliable to key into, improving adhesion and adding a first layer of resistance to water and alkaline moisture from the substrate. It's ready for the topcoat 2-3 hours after application (within an 8-hour window).

Ecostar 2K HD goes on top. It's a two-component (10:2 mix ratio, plus 10% water), water-based aliphatic polyurethane lacquer. Aliphatic rather than aromatic chemistry matters here because it's inherently non-yellowing, which is what keeps a clear or light microcement finish looking clear rather than ambering under UV exposure. It moves fast: dust-dry in 30 minutes, fingerprint-dry in 2 hours, ready for a second coat without sanding in 3-4 hours.

The Satin Finish

Ecoflor supplies Ecostar 2K HD in a satin, low-sheen finish (15 GU). It's the sweet spot for microcement: enough sheen to bring out the depth of the finish without the "plastic" look of a full-gloss coating, and without showing every trowel mark the way high gloss does. A lower-sheen finish is also inherently less slippery underfoot than gloss, which matters in wet areas.

Slip Resistance for Wet Areas

For bathrooms, showers, and other barefoot wet areas, Ecoflor's EcoGrip Anti-Slip additive is dosed directly into the Ecostar 2K HD mix. This isn't a generic claim: the Ecostar 2K HD + EcoGrip combination has been independently tested to AS 4586 (Wet Pendulum Test) by a NATA-accredited lab:

• EcoGrip at 2.5% dosage (25g per litre of sealer): SRV 47 on Slider 96 → classified P4
• EcoGrip at 5% dosage (50g per litre of sealer): SRV 57 on Slider 96 → classified P5 (the highest AS 4586 rating), and SRV 43 on Slider 55 → P4

For a continuous barefoot wet area such as a shower floor, the 5% dosage is the one to use: it clears P4 on both test rubbers and reaches P5 on the standard slider. The base sealer (without EcoGrip) also carries European slip data: DIN 51130 ramp test and EN 13036-4 pendulum test results, both run on the Prymaren + Ecostar 2K HD cycle.

Chemical Resistance and Easy Cleaning

Ecostar 2K HD meets UNI 11021, the Italian standard for food-contact environments, a stricter benchmark than most bathroom or kitchen sealers are tested against. In practice, that means the sealed surface:

• Can be washed with chloroactive detergents, alkaline degreasers, and acid-based descalers without blistering or damage
• Can be disinfected with standard disinfectant-grade cleaners
• Resists staining from acetic acid, ammonia, coffee, ethanol, condensed milk, olive oil, and tea (any residual mark can be lifted within 24 hours with a mild surfactant solution)
• Is suitable for cold rooms and environments with humidity above 80%

This is the certification that answers the "will it get grubby and hard to clean" question that comes up with cement-based surfaces. A properly sealed microcement floor is cleaned the same way as any hard, non-porous surface.

Breathability and Crack-Bridging

Ecostar 2K HD is tested to UNI EN ISO 7783 for vapour permeability, meaning the sealed surface can still let moisture vapour escape from the substrate rather than trapping it, which matters on slabs exposed to ambient humidity. It's also rated for crack-bridging up to 411 microns, which allows it to flex over the fine hairline cracking that can appear in a cement-based substrate without the coating itself splitting.

One caveat worth flagging: the sealer should not be applied over a substrate with active rising damp. If there's any doubt about subfloor moisture, check it before sealing rather than after.

Sealing Over an Old or Previously Treated Floor

If you're resealing an existing microcement floor rather than sealing a fresh one, you don't need to strip back to bare microcement in most cases. Ecostar 2K HD is designed to bond to and protect an existing resin sealer, so a light sand is usually enough to key the surface before applying a fresh coat, bringing the floor back to like-new condition. If the old sealer is heavily worn, contaminated, or failing, a full strip followed by 180-grit sanding and a thorough vacuum is the more thorough approach.

Durability and Repair

The finish is a walkable, abrasion-resistant film rather than a penetrating treatment, which means localised wear in high-traffic zones can be refreshed with a light sand and recoat rather than stripping and resealing the whole floor.

Which Sealer Kit Do You Need?

• Prymaren primer: 1kg kit for small areas and touch-ups, 5kg kit for full floors and larger rooms.
• Ecostar 2K HD topcoat: 1.2kg kit (1:0.2 ratio) for small wall or floor sections, 6kg kit (5:1 ratio) for full floor coverage.
• EcoGrip Anti-Slip additive (250g): add to the Ecostar 2K HD mix for any wet area, bathrooms, showers, laundries, and outdoor wet zones.

All three are available from the Ecoflor Sealers collection, and full technical data sheets are on the Technical Data page if you want the certification detail for a project file or trade specification.

FAQ

Do you need to seal a microcement floor?
Yes. Microcement is a cement-based, absorbent finish until it's sealed. Without a topcoat it will stain permanently and has no real water or chemical resistance. Sealing with Prymaren + Ecostar 2K HD is what makes it functional as a floor or wall surface, not just a decorative one.

What's the difference between Prymaren and Ecostar 2K HD?
Prymaren is the primer: a single-component acrylic that bonds to the microcement and preps it for the topcoat. Ecostar 2K HD is the topcoat: a two-component polyurethane lacquer that provides the actual water, chemical, and abrasion resistance. Both are needed; Prymaren isn't a substitute for a topcoat, and Ecostar 2K HD adheres and performs best when applied over it.

Is Ecostar 2K HD sealer waterproof?
It's a water-resistant, vapour-permeable protective film rather than a fully impermeable membrane, which is intentional: it needs to let the substrate breathe. For continuous water exposure (shower floors, wet rooms), pair it with the EcoGrip additive for slip resistance and follow correct surface prep, since the system is designed and certified for exactly these environments.

Will the sealer make a microcement floor slippery when wet?
It depends mainly on the additive used, not the sealer itself. The satin finish we supply is already less slippery than a gloss coating, and it can be improved further with the EcoGrip Anti-Slip additive, which is independently tested to AS 4586 and reaches the highest slip rating (P5) at a 5% dosage.

How long does the sealer take to cure?
Ecostar 2K HD is dust-dry in 30 minutes and fingerprint-dry in 2 hours, with a second coat applicable after 3-4 hours without sanding. Full hardness for light foot traffic typically follows within 12-24 hours; heavier use should wait longer.

Can this system be used in bathrooms and showers?
Yes. This is one of its main use cases. With the EcoGrip additive dosed at 5%, the system is tested for wet, barefoot conditions and is also certified to the UNI 11021 food-contact hygiene standard, which covers the kind of daily chemical and moisture exposure a bathroom sees.

Can a worn microcement floor be resealed?
Yes. Localised wear can be refreshed with a light sand and recoat, since Ecostar 2K HD is designed to bond to and protect an existing resin sealer. A full is only needed if the old sealer is heavily worn, contaminated, or failing.