How to remove mould with baking soda (and when it fails)

What baking soda can and can’t do

Baking soda is a mild alkali that absorbs moisture and deodorises, and it can lift light surface mould from non-porous materials. It’s a reasonable first step for a small, fresh patch on a sealed surface. What it can’t do is kill mould that has rooted into a porous material, reach growth hidden behind a surface, or stop mould returning if the moisture that caused it is still there. Knowing that line is the difference between a quick fix and a problem that quietly gets worse.

How to use it for light surface mould

For a small patch on tile, grout, a sealed window frame or a wipeable surface:

1. Make a paste. Mix baking soda with a little water to form a paste, or dissolve a tablespoon in a spray bottle of warm water.
2. Apply and leave briefly. Spread the paste over the patch or spray the surface and leave it for 10–15 minutes.
3. Scrub gently. Use a brush or cloth to lift the growth. Don’t scrub so hard you damage the surface underneath.
4. Wipe and dry. Remove the residue with a damp cloth, then dry the surface thoroughly — mould returns fastest on a surface left damp.
5. Leave a light dusting. A thin film of baking soda left behind absorbs residual moisture and deodorises the area.

Open a window while you work and avoid dry-brushing the patch, which releases spores into the air.

Where it actually works

Baking soda is worth trying when all of these are true:

• The patch is small — roughly under a square metre.
• The surface is non-porous or sealed: tiles, grout, glass, metal, painted wood that’s intact.
• The growth is recent and on the surface, not stained deep into the material.
• You know the moisture cause and can fix it (a window you can keep dry, a vent you can open).

When baking soda fails

It fails — and can make things worse — in several common situations:

• Porous surfaces. Plaster, bare concrete, untreated wood, wallpaper and MDF absorb mould’s root structure (hyphae). A surface scrub lifts the visible growth but the roots remain, so it regrows from inside the material.
• Deep or established growth. A patch that’s been there for weeks, or has spread across a wall, is past a paste-and-wipe. The colony is in the substrate.
• Hidden mould. If the smell is strong but the visible patch is small, there’s likely more behind the surface. Baking soda can’t reach it.
• Recurrent mould. If the same spot comes back after you clean it, the moisture source hasn’t been addressed. No amount of baking soda breaks that cycle.
• After water damage. Flooded or leak-affected walls need drying and proper treatment, not a surface clean.

There’s also a common myth that bleach followed by baking soda is a “deep clean.” Bleach lightens the stain but doesn’t kill roots in porous materials, and it adds moisture and fumes. It’s a cosmetic fix dressed up as a remediation.

The risk of DIY on the wrong patch

Disturbing a larger or deeper patch releases spores into the room, where they settle and start new colonies. A surface clean can also give false confidence: the wall looks better, so you stop looking, while the growth continues inside the material. By the time it reappears, the area affected is larger and the removal harder.

When to call in professionals

It’s time to stop with the baking soda and book a proper job when:

• The patch is larger than about a square metre, or spreading.
• It’s on a porous surface — plaster, bare wood, wallpaper.
• It keeps coming back after cleaning.
• There’s a strong musty smell but little visible growth (a sign of hidden mould).
• The property has had a leak, flood, or a long period closed up.
• Anyone in the home has a respiratory sensitivity.

For anything beyond a small, fresh, surface patch, mould removal in Larnaca covers the containment, HEPA cleaning and anti-microbial treatment that baking soda can’t. And if you’re not sure how far it goes, book an inspection first — the inspection fee is credited toward any removal you proceed with.