March 24, 2026 · 6 min read
What surface preparation actually involves
This is the least glamorous part of the work, the largest share of most quotes, and the single strongest predictor of whether you will still be happy with the wall in five years.
Assessment comes first
Before anything is touched we establish what is actually there: the substrate, the coatings on it, whether there is moisture, and whether anything is moving.
Moisture and movement both change the approach fundamentally. Finding them at the start is inconvenient. Finding them halfway through is expensive.
Making the wall flat
Thin finishes reveal the plane they are applied to. Filling, skimming, and sanding until the surface is genuinely flat is the bulk of the labor on an older wall.
The test is raking light. We put a lamp close to the wall and look along it, because a surface that reads flat under ambient light will show every imperfection under a low sun in five years.
Dealing with what is already on it
Old paint has to be sound and compatible. Loose or flaking coatings come off. Glossy surfaces need keying so the new material has something to grip.
On an old wall we sometimes find several generations of coating, one of which is impermeable and trapping moisture. That has to be addressed before a breathable finish will do its job.
Priming and reinforcement
The right primer depends on both the substrate and the finish going over it. Microcement additionally gets a reinforced base coat, which bridges joints and absorbs the small movement any building makes.
In short
If a quote does not describe the preparation, it is not really a quote. Ask what is included and what happens if the wall turns out to be worse than it looks.
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