Kerakoll Keradur Eco deep primer for absorbent screeds

Does the cement screed leave dust on your hand when you run it over the surface? Adhesive cannot bond well to dust. The liquid deep primer penetrates the absorbent substrate and binds the dusty surface. Ready to use: apply with a brush, roller or watering can. Ceramic can be laid over it after 24 hours at +23 °C. This is Kerakoll Keradur Eco.

• Dusty, poorly compacted cement screed before covering installation: absorbs quickly and deeply - restores the continuity of the surface layer; it does not strengthen structurally weak screed
• Part of the system: the first layer in floor covering installation - followed by tile adhesive or parquet, PVC or carpet adhesive; also beneath Keralevel Eco levelling compound on highly absorbent substrates, with an adhesion promoter
• Ceramic, stone, parquet, carpet and resilient flooring: one primer beneath bonded floor coverings - ceramic after ≥ 24 hours; parquet and resilient flooring when substrate moisture is ≤ 2%
• Underfloor heating: also suitable for cement screeds with underfloor heating - the same primer is used in heated and unheated rooms
• Highly absorbent substrate: apply several coats, allowing the previous coat to dry completely - apply so that the substrate absorbs it completely, leaving no glossy film
• Living areas: EC 1 plus and A+ - water-based, very low VOC emissions
• Not a finished surface on its own: a covering or levelling compound must be applied over it - before applying levelling compound, smoothing compound or plaster, Active Prime Fix or Active Prime Grip adhesion promoter is recommended

What is it suitable for?

Suitable substrates: Absorbent cement screed; cement plaster and cement-lime mortar - for floors and walls, including underfloor heating.

Coverings and possible top layers: Ceramic, porcelain stoneware, marble and natural stone, parquet, carpet, resilient flooring. Mineral and mineral-organic adhesives; dispersion and reactive adhesives; mineral skim coats, levelling compounds and self-levelling compounds; cement- and gypsum-based plasters.

Areas: Indoor and outdoor areas — residential, commercial, industrial and public spaces.

Not suitable:

• As a standalone surface (without covering or levelling compound)
• For non-absorbent substrates — use Active Prime Fix there
• For gypsum and anhydrite screeds
• For damp substrates prone to moisture ingress; in constantly wet rooms
• As waterproofing
• To increase the mechanical strength of weak substrates

The system in which you are working

Which primer is needed? — Deep primers and surface hardeners

Frequently asked questions

What should be used to treat a dusty screed before tiling?
Use a water-based primer that penetrates deeply into the absorbent cement screed. First remove loose and crumbling areas, vacuum up the dust, and roughen any dense surface crust. Ceramic tiles can be installed after 24 hours.

What primer is needed under tile adhesive on a screed?
Use a primer on absorbent cement screeds, such as Keradur Eco. On non-absorbent surfaces - old tiles, stone, or wood - use a bonding primer: Active Prime Fix. The same product is also required for gypsum and anhydrite screeds.

How long before the flooring can be installed?
Ceramic tiles can be installed after at least 24 hours, once the treated surface has cured; curing takes longer in cold and humid conditions. Parquet and resilient flooring can be installed only at a maximum moisture content of 2%, measured with a carbide meter. The requirements of the flooring and adhesive must also be met.

Does it strengthen a weak screed?
No: it binds the friable, weakly compacted surface layer but does not increase the strength of a weak screed. Loose or cracked screeds must be repaired. Before installing parquet, the substrate must be checked with a pull-off test.

Is it also suitable for gypsum or anhydrite screeds?
No, it is intended only for cement-based substrates. Active Prime Fix is required for gypsum and anhydrite screeds. It separates the gypsum from the cement-based layer.

Keradur Eco or Active Prime Fix?
Keradur Eco primer is for absorbent cement screeds, at 0.5–2 kg/m². Active Prime Fix is a bonding primer for non-absorbent and gypsum substrates, at 0.1–0.2 kg/m². Before applying a levelling or smoothing compound, an additional bonding primer is recommended after Keradur Eco.

How much primer is needed per m²?
≈ 0.5–2 kg/m², depending on the substrate's absorbency. One 25 kg container is enough for ≈ 12.5–50 m². Highly absorbent substrates require more coats and more material.

When should I not use it?
Not on non-absorbent, gypsum, or anhydrite substrates. It is also unsuitable for wet or damp substrates and permanently wet rooms. It is not intended for waterproofing.

Can it be purchased separately?
Yes, for example if you already have the adhesive and covering. It can also be purchased separately for the screed in one room. It is also suitable for touch-ups if the absorbent substrate has taken up more material.

Can I apply it myself?
Yes: evenly, using a brush, roller, or watering can. Make sure no standing liquid or glossy film remains on the surface. Before installing parquet, it is advisable to have the moisture measurement and pull-off test carried out by a professional.