Preparing concrete floor for epoxy: cleaning, degreasing, priming, repairing

In brief: the coating is only as sound as the substrate

If an epoxy floor coating remains tacky, blisters or peels, the final coat is often not the cause. The substrate may have been dusty, greasy, too smooth, too damp or unsound. Preparation is not a stage to rush.

A concrete substrate for epoxy must be clean, dry, sound, free from grease and suitably primed. These basic conditions often determine whether the floor performs properly.

Which surfaces are suitable?

Depending on the product, concrete, cement, screed, mineral substrates, tiles, wood or metal can be coated. For garages and workshops, 2K epoxy floor coating for garage and workshop is intended for concrete, cement, screed, wood and metal. 2K epoxy floor coating matt is suitable for concrete, wood and screed floors. For balconies, terraces, concrete and tiles, 2K epoxy floor coating for balconies, terraces and concrete is the right direction.

However, the product list is not a release for every condition. A concrete floor may be suitable and still need to be prepared first. Tiles can be suitable and still not hold if they are hollow or not sanded and primed. Old paint may be suitable and still need to be removed if it comes off.

Step 1: clear the floor and check for moisture

Clear the area completely. Shelving, tyres, tools and boxes obstruct the work and may hide problem areas. Then check whether the floor is dry. Moisture commonly causes poor adhesion, blisters or dull patches.

In garages and basements you should pay particular attention to dark spots, efflorescence, musty smells, damp wall connections and old water points. If moisture comes from below, a coating will not solve the construction problem. Then the cause must first be clarified.

Step 2: Remove dirt, dust and loose parts

Loose components must be removed. Sweeping alone is rarely enough. The floor should be vacuumed thoroughly, especially after sanding or repairs. Dust acts like a separating layer between concrete and coating.

Old loose paint, flaking areas, crumbling screed or poorly adhering coatings must be removed mechanically. If an old coating is to remain, it must be tight and compatible with the new system. If in doubt, a test area makes more sense than risking a full garage floor.

Step 3: remove oil and grease

Oil is one of the biggest enemies of a floor coating. In garages it often penetrates deep into the concrete. A dark spot is not just a visual issue, but an adhesion risk.

Universal degreaser cleaner removes grease, oil and stubborn dirt from many surfaces in the home, garage and workshop. It is ready to use, solvent-free and can also be used to prepare the surface before painting and coating. After cleaning, the surface should be wiped with clean water and allowed to dry completely.

For old, deep oil stains, cleaning alone is not always enough. The area may then need to be sanded or otherwise mechanically prepared.

Step 4: Roughen smooth concrete surfaces

New or power-smoothed concrete surfaces can be very dense. Then the coating has little hold. Even old concrete can be so slippery or dirty on the surface that preparation is necessary.

Concrete etching solution for floor preparation is intended for concrete, screed and cement substrates. It cleans intensively, removes dirt and grease and lightly roughens difficult surfaces. Depending on the substrate, consumption is around 1 litre per 5 to 8 m².

Alternatively, mechanical grinding may be necessary. It is always important to remove sanding dust thoroughly afterwards. Otherwise the coating will be on a separating layer again.

Step 5: Repair cracks, holes and chips

A floor doesn't have to look new, but it should be stable. Cracks, holes, chips and crumbling areas should be repaired before coating. Otherwise they stand out, collect dirt or lead to weak points.

2K repair mortar is an epoxy mortar for breakouts, holes, cracks and defects in concrete and screed floors. It is suitable for garage floors, stairs, basement floors and surfaces subject to traffic. The processing time is approx. 30 minutes at 20 °C. The consumption is approx. 2 kg/m², depending on the layer thickness.

Repairs should be completely solid before coating. Transitions must be sanded clean and dusted.

Step 6: Choose primer

Primer is not mandatory on every surface, but it often stabilises a floor coating system. It can regulate absorbency, consolidate friable surfaces and improve adhesion to smooth substrates.

2K epoxy primer is a solvent-free 2K epoxy primer for concrete, screed, cement-based substrates, mineral surfaces, mastic asphalt and old paint. It is mixed in a ratio of 2:1, has a processing time of approx. 20 to 30 minutes at 20 °C, can be walked on after approx. 10 hours and is completely hardened after approx. 7 days.

Special adhesive primer is a solvent-free polymer dispersion for concrete, screed, tiles and mineral substrates before floor paint, epoxy and floor coating. It can act as an adhesive bridge on smooth surfaces and reduce the absorption capacity on absorbent surfaces.

Which primer is suitable depends on the substrate, subsequent product and load. If you are torn between the two, the underlying issue is more important than the desire for the simpler solution.

Prepare tiles

Tiles are a special case. They can be suitable as a substrate if they are firmly seated, clean, dry and stable. Hollow tiles, damaged joints or loose edges are a risk.

Before coating, tiles should be degreased, sanded or prepared with a suitable adhesive primer. Depending on the structure, the joints can remain visible. If you expect a smooth, seamless look, you have to level the surface accordingly.

Check old coatings

Old floor paint is comfortable if it lasts. If it doesn't hold up, it's a problem. Do simple checks: scratch, tape test, sand in an inconspicuous area. If the old layer comes off, chalks or becomes soft, it does not belong under a new 2K coating.

Depending on the structure, 2K epoxy primer can be used as an adhesion promoter for stable old coatings. The compatibility of the system still matters.

Preparation as a checklist

Everything should be done before mixing the 2K coating:

• Area cleared.
• Surface dry and stable.
• Dust, dirt and loose parts removed.
• Oil, grease and tyre residue removed.
• Smooth or difficult surfaces prepared.
• Cracks, holes and chips repaired.
• Primer chosen appropriately and cured.
• Tool, edge areas and amount of material planned.

If you only look for tools after mixing, the preparation is not finished.