Short answer: for facades, pavers, boundary walls and worktops in India, choose a penetrating, breathable water repellent rather than a film-forming sealer. A penetrating treatment soaks into the pores and makes them shed liquid water, while still letting water vapour out, so the masonry can dry after the monsoon. A surface film that traps moisture is what leads to blistering, flaking, white salt deposits and damp patches indoors.
Why masonry needs to breathe
Stone, brick, concrete and render are porous. They take in water from rain, ground splash and cleaning, and they give it back as vapour when the weather turns dry. Problems start when something stops that second half of the cycle.
The US National Park Service draws a clear line between the two kinds of product. Water-repellent treatments resist liquid water but let water vapour pass, and are usually clear. Waterproof coatings block both liquid and vapour, and are usually opaque, like bituminous or elastomeric paints. Its guidance is that waterproof coatings almost never belong above ground on masonry, because moisture that gets behind them cannot escape and can push the coating, and the face of the masonry, off the wall. (Preservation Brief 1, National Park Service.)
In Indian conditions that matters twice over: long monsoons soak walls for weeks, and hot dry months then pull the water back out. A treatment that keeps rain out but lets the wall dry is the one that survives that cycle.
Penetrating repellent or film-forming sealer?
| Penetrating water repellent | Film-forming sealer or coating | |
|---|---|---|
| Where it sits | Inside the pores, just below the surface | On top, as a continuous film |
| Water vapour | Passes through, so the masonry can dry | Largely blocked; moisture can build up behind it |
| Appearance | Looks like the untreated surface | Often adds gloss or a wet look; can yellow |
| How it ages | Gradually stops beading; re-treat that area | Peels, flakes or blisters; must be stripped |
| Slip on paving | Surface texture unchanged | Can make paving slippery when wet |
Match the treatment to the surface
- Sandstone, limestone and Kota-type stone: porous and prone to staining and moss. A penetrating repellent keeps rain and dirt from soaking in.
- Granite and honed marble: dense, so they take up less liquid. Wipe off any surplus within 10 to 15 minutes so nothing dries on the surface.
- Exposed brick, concrete and render: the classic monsoon problem surfaces, prone to damp patches, efflorescence and algae.
- Pavers, driveways, patios and pool surrounds: a penetrating treatment keeps the grip of the surface as it is.
- Unglazed tiles, terracotta and grout: treat them like stone. Glazed tiles and glass need a coating made for glass instead.
What a repellent cannot fix
A water repellent protects the face of the wall from rain and splashes. It is not a cure for water that arrives some other way. Before treating, fix leaking gutters and downpipes, failed pointing, cracks and overflowing terraces. It is not a below-ground waterproofing system, it should not go on surfaces under constant water pressure, and new concrete needs at least 28 days to cure first.
How to apply it properly
Prepare
- Clean off dirt, oil, efflorescence, moss and old coatings, then rinse.
- Let the surface dry for at least 24 to 48 hours.
- Do the water test: sprinkle water on it. If it darkens and soaks in, it is ready. If it beads, an old sealer is still there and must be removed first.
- Pick a dry spell: 5 to 35 °C, with no rain expected for 12 hours. Treat a small test area first.
Apply
- Dilute the concentrate with deionised water on site, at the ratio on the data sheet, and mix well.
- Apply liberally with a low-pressure sprayer, brush or roller until the surface looks evenly wet. Expect 70 to 100 ml of diluted product per m², more on very porous stone.
- On polished or dense stone, wipe off surplus within 10 to 15 minutes.
- Apply one coat only. Once the first coat is water-repellent, a second cannot penetrate.
- Keep foot traffic off for 6 hours and keep the surface dry for 24 hours. Full performance develops over about 5 days.
Nanoman Stone + Brick at a glance
| Item | Figure |
|---|---|
| Type | Penetrating, breathable water and stain repellent; PFAS-free |
| Supplied as | Concentrate in 10 L cans, diluted with deionised water on site |
| Coverage | 70 to 100 ml of diluted product per m², about 10 to 14 m² (110 to 150 sq ft) per litre |
| Touch dry | 2 to 3 hours |
| Full effect | About 5 days |
| Lasts | Up to 5 years, depending on exposure |
See the full specification on the Stone + Brick product page, read our stone, brick and concrete sealing guide and protecting exteriors from monsoon damp, or ask for a trade quote with your surface and area.
Frequently asked questions
Will a water repellent stop rising damp?
No. A penetrating water repellent keeps rain and splashes out of the face of the masonry. Rising damp, leaking gutters, failed pointing and water under pressure need to be fixed at the source, and below-ground waterproofing is a different job.
Does sealing change the colour of stone or brick?
A penetrating repellent is designed to leave the surface looking as it did. Some dense or dark stones can deepen slightly in colour, so treat a small, hidden area first and judge it once dry.
Can I seal new concrete or fresh plaster?
Wait at least 28 days so the material has cured and dried out. Sealing too early traps moisture that still needs to leave.
How do I know when it needs re-applying?
Sprinkle water on the surface. While it beads and runs off, the treatment is working. When it darkens and soaks in, clean that area and treat it again. Nanoman Stone + Brick lasts up to 5 years, depending on exposure.
Is it suitable for kitchen worktops?
It works on stone worktops such as granite and honed marble, where it helps keep spills from soaking in. Wipe spills promptly, especially oil and acidic liquids such as lemon juice, which can still mark calcareous stone like marble.