Master Guide: How to Apply Single-Coat Mortar with Projected Aggregate

The projected aggregate finish is, without a doubt, the most durable and robust option among facade coatings. By embedding natural stone into the fresh mortar, we create a protective shell that resists impacts, hides dirt, and offers an unparalleled organic design.

At Vetonek, as specialists in aggregates and mortars, we explain the keys to making the stone stay "stuck" forever and the finish remain uniform.

1. The perfect combination: Mortar + Stone

The success of this facade depends on the affinity between the two materials. It is not only about the color, but also about the technique:

• The Mortar: It must have a creamy consistency and a sufficient "open" time (the time it remains fresh) to receive the stone.

• The Stone (Aggregate): It is essential that the stone be washed and free of dust. If the stone has traces of soil or quarry dust, the mortar will not "grab" the grain and the stone will eventually fall off over time.

💡 Vetonek Tip: Don't limit yourself to gray. Try combining white mortars with bluish-gray stone, or cream-colored mortars with Saturn yellow stone for exclusive finishes.

2. Step by step: The Projection Technique

A. Preparation and Screeding

The single-coat mortar is spread over the substrate (brick, block, etc.) with a thickness of about 10-12 mm. It is vital to use a straightedge to ensure the surface is flat, as the stone will replicate any irregularity in the wall.

B. The critical moment: The Projection

This is where the quality of the work is decided. The stone should be projected manually (with a hand thrower) or mechanically while the mortar is still fresh and pasty.

• Saturation: Stone must be thrown on abundantly. The goal is for the stone to cover the entire surface of the mortar. What is left over will fall to the ground (it can be collected if the ground is clean).

• Distance: Project from about 20-30 cm from the wall so the stone embeds with just the right force: not so hard that it sinks in, and not so lightly that it only rests on the surface.

C. The "Flattening" or Embedding

Once the stone has been projected, a clean plastic or metal trowel should be passed gently over it. This step is vital to press the stone into the mortar and ensure it is laterally enveloped by the mix, guaranteeing its permanent fixing.

3. Material Calculations (Avoid running short)

To achieve a "saturated" finish (so the mortar background is not overly visible), the quantities are clear:

• Mortar: 15-18 kg per m².

• Stone: 8-10 kg per m². It is always better to have extra stone so you can project it forcefully and ensure every corner is covered.

4. Specific Pathologies of Projected Aggregate

Why does the stone fall off?

1. Dirty stone: Dust acts as a release agent. Always use high-quality washed aggregate.

2. Mortar too dry: If you take too long to project, the mortar forms a dry "skin" and the stone will not embed. Work in small sections.

3. Lack of pressure: Not passing the trowel after projection to embed the stone in the mix.

Why do stains or "bare patches" appear?

They are due to irregular projection. If the thrower does not maintain a steady rhythm, there will be areas with a lot of stone and others where the mortar "drip" will show. The key is uniformity.

5. Maintenance and Durability

One of the great advantages of this system is that it does not need paint.

• If over the years the facade accumulates pollution, a simple pressure wash will restore the natural stone's original shine.

• As it is natural stone, the color is eternal; it does not degrade under the sun's UV rays.

Do you need the complete pack?

At Vetonek/Canteras El Cerro we are manufacturers. We have one-coat mortar in the color you want and the widest variety of pebbles and gravels for spraying in the entire Peninsula.

[Check our catalogue of aggregates for spraying here] and start your project with the confidence of buying direct from the factory.