Wall with efflorescence: what to fix before repainting
The white powder that pushes the paint off doesn't get fixed with another coat of paint. Here's what it is, where it comes from, and what to do in order, based on technical documents. Guide prepared by Gallardía.
Short answer
Efflorescence is a deposit of salts that water carries from inside the wall to the surface. If the water keeps getting in, the efflorescence comes back.
ℹ The essentials in 60 seconds
What it is. A white crystalline deposit of water-soluble salts that appears on the surface of masonry. Source: Brick Industry Association, Technical Note 23A, p. 1
Why it shows up. Three conditions have to coincide: salts in the wall or in contact with it, enough water to dissolve them, and pores for the solution to reach the surface through. Source: Brick Industry Association, Technical Note 23A, pp. 1 and 2
What works best. The most effective way to prevent it is reducing the water that enters the wall. Source: Brick Industry Association, Technical Note 23A, p. 4
How to remove it. Dry brushing is effective; wet washing can bring more salts to the surface. Source: Brick Industry Association, Technical Note 23A, p. 9
⚠ No specific Panamanian standard
We found no official Panamanian standard on efflorescence in walls. This guide uses technical documents from a masonry industry association and a manufacturer's data sheet, identified in the sources section.
Where the salts and the water come from
Inside and around the wall
Mortar and stucco (from cement alkalis), concrete and concrete block, brick to a lesser extent, coping units, and soil or groundwater in contact with the wall. Source: Technical Note 23A, pp. 2 to 4
Rain, ground, construction and condensation
Rain penetration, groundwater rising by capillary action, moisture from the construction itself, and condensation from humidity differences. Source: Technical Note 23A, pp. 4 to 6
Questions to locate the water
The sources above work as a checklist. These questions aren't a diagnosis; they help whoever assesses the wall start in the right place:
| What you see | Water source to rule out first |
|---|---|
| Stains low on the wall, near the floor or planters | Groundwater rising by capillary action |
| Stains under windows, eaves, gutters, or on walls exposed to rain | Rain penetration |
| Shows up on recently finished construction | Construction moisture |
| Cold wall in a closed or air-conditioned room | Condensation |
What to do, in order
- Locate and fix the water entry point. Without this step, everything else is temporary. Source: Technical Note 23A, p. 4
- Let the wall dry for as long as it takes after fixing the cause.
- Remove the efflorescence with a dry brush, without washing the wall. Source: Technical Note 23A, p. 9
- If you're using an anti-efflorescence sealer, follow its technical data sheet: do a test patch first and respect the number of coats and drying times. Source: Sika, Sika Zero Salitre data sheet
- Paint only once the sealer's manufacturer allows it.
What an anti-efflorescence sealer data sheet says
As an example, here's what one manufacturer publishes for its product. Every brand has its own data sheet, and you need to read the one for the product you'll actually use.
| Data sheet point | What it states |
|---|---|
| Coats | Minimum two on highly absorbent surfaces |
| Between coats | 2 to 3 hours drying time |
| Before painting or plastering | Minimum 24 hours |
| Temperature | +5 °C to +35 °C for material, surface and ambient |
| What it doesn't solve | Limit Condensation on cold walls in poorly ventilated spaces, and surfaces so damaged they need replacing |
| Recommendation | Preliminary test before applying over the whole surface |
⛔ The most expensive mistake
Painting or sealing over it without cutting off the water. The manufacturer itself acknowledges that its sealer doesn't fix condensation or a badly deteriorated base. Source: Sika, Sika Zero Salitre data sheet
We don't repaint without locating the water
At Gallardía, when a wall has efflorescence, the quote is split into two parts: fixing the source of the water, and preparing and painting. That way you know exactly what you're paying for, and why.
Related questions
Does efflorescence go away on its own?
Can I wash the wall with water to remove it?
Does a "damp-proof" paint fix it?
How much does painting cost after treating the efflorescence?
Sources
Consulted on September 29, 2026.
Notice. This guide is general information for educational purposes and does not replace an on-site assessment of the wall. Mentioning a product is an example of a technical data sheet, not a commercial recommendation. Verified on September 29, 2026. Prepared by Gallardía (gallardia.lat).
Keep reading on Gallardía
This guide is part of gallardia.lat's content on painting and moisture.