Applying mortar plaster smooths rough surfaces on raw concrete, brick, or stone walls, delivering a sleek finish while preventing cracks. As seasoned builders know, mastering this technique ensures durable, professional results. Follow these proven steps and avoid common pitfalls for success.
Essential tools include a brush, ruler, plumb line, trowel, and sponge. Start by cleaning and moistening the wall thoroughly to create an ideal bonding surface and eliminate impurities.
Brush vigorously, then spray with water. This keeps the wall from drying out and absorbing excess moisture from the plaster. Next, project the "gobetis"—a thin, diluted primer—onto the damp wall. It enhances flow, adhesion, and acts as a key. Immediately apply the main mortar coat with the trowel, before the gobetis dries.
Secure verticality with pre-placed wooden blocks or markers. Verify alignment using a long wooden or aluminum ruler and a plumb line. Adjust wedges by pulling or pushing as needed.
Maintain 1-2 cm thickness. Fill wedge holes and imperfections with mortar, then smooth with vigorous circular trowel strokes. Finish with light circular passes of a damp sponge for a flawless surface.
Mortar plaster provides a versatile base for any topcoat. Apply three successive layers without full drying: first fluid and thin, second compact and thicker, third thin. Mix mortar fresh right before use to prevent quick setting. Consult pros for advice if needed.
