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Surface Preparation

How to Make and Apply a Successful Slurry

A slurry primer is a thin cementitious bonding layer used on dense or non-absorbent surfaces before tiling. Its purpose is simple: it creates a new cement-based surface that tile adhesive can bond to properly. On smooth or sealed substrates, tile adhesive alone cannot grip reliably. Even if tiles appear bonded at first, failure often occurs later. A correctly applied Kwik-Key slurry prevents this by providing both chemical and mechanical bonding.

Do I need Slurry?

You need slurry if water beads or runs off the surface instead of soaking in.

Slurry is typically required on:

  • Existing tiles (tile on tile)
  • Power-floated or very smooth concrete
  • Painted or sealed surfaces
  • Dense fibre cement boards in wet areas
  • Approved vinyl floors
  • Polished or vitrified surfaces
  • Bricks and mortar joints must be firm with no movement. Tile adhesive cannot compensate for loose bricks or weak mortar

If in doubt, use slurry. It removes the risk.

What You Need?

Accuracy and proper tools matter for slurry. Do not shortcut this step.

You will need:

  • Kwik-Key
  • KWIKbase
  • Clean mixing bucket
  • Measuring container
  • Electric drill
  • Mixing paddle
  • Block brush or long-bristle brush

The surface must already be sound, clean, dry, and free from grease, wax, polish, or silicone.
Slurry is not a cleaner, leveller, or repair product.

Mixing The Slurry

Ratio: 2 parts KWIKbase to 1 part Kwik-Key

Add both components to the bucket and mix using a drill and paddle until smooth and lump-free.

Allow the mix to stand for 3 minutes to develop properly, then remix briefly before use.

The correct consistency is:

  • Brushable
  • Similar to thick paint or thin plaster
  • Not runny
  • Not dry or crumbly
  • Do not add extra water

Because the sand and heavier material can settle, stir or remix the slurry occasionally during use to maintain a consistent mix.

Applying the slurry

Apply slurry using a block brush or long-bristle brush.

Coats

  • Brush on a uniform layer about 2 mm thick, working it firmly into the surface. Ensure there are no thin patches, pinholes, or exposed glossy areas.
  • Allow the first coat to become touch dry before applying a second coat if required.
  • Apply the second coat in the opposite direction to the first to ensure even coverage.

Drying before tiling

  • Allow 24 hours after final coat before tiling, waterproofing, screeding, or applying levelling compounds.

Do not tile onto slurry that is still damp or soft. Trapped moisture weakens the bond.

What slurry does not replace

Slurry improves bonding, but it does not fix underlying problems.

It does not replace:

  • Crack repair
  • Levelling
  • Waterproofing
  • Cleaning or sanding
  • Structural repairs

If the substrate is moving, damp, or contaminated, fix that first.

Common mistakes to avoid

Before tiling, confirm:

  • Slurry is fully dry
  • Surface feels hard and cement-like
  • No glossy substrate is visible
  • Coverage is uniform across the area
  • Dirty or greasy surfaces

If these are met, tiling can begin.

Final rule

If the surface does not absorb water, slurry is required.
Skipping slurry where it is needed will eventually lead to failure.