Damp & Stain Blocking Painters in London
The reason your ceiling stain keeps coming back through two coats of white emulsion is that you're painting the wrong product on it. We specialise in permanent stain and damp isolation using the right sealer for the actual stain — not a hopeful extra coat of paint.
Damp & Stain Blocking across London
Most 'ghost stains' that keep bleeding through paint are one of five things: water damage from a plumbing leak; nicotine; efflorescence (salts) on a wall that's been damp; smoke or fire damage; or rust from a nail head or old fixing. Each one needs a different sealer. Vinyl matt over the top will absolutely not work — the stain will bleed back within a week. We know because we're regularly called to fix exactly that.
Our stain-block spec is chosen at the survey. Zinsser BIN (shellac-based) for the toughest stains: nicotine, water rings, biro, felt-tip, smoke damage. Zinsser Cover Stain (oil-based) for large areas of nicotine or new timber knots. Zinsser Perma-White for previously mouldy bathrooms (with mould treatment first). Owatrol ESP for glossy or awkward substrates. Specialist damp coatings (Sika, Thompson's) where surface damp needs isolating pending a proper damp fix.
We're careful to distinguish 'stain blocking' from 'damp fixing'. If you have rising damp, penetrating damp from a broken gutter, or a live plumbing leak, no paint will fix it — you need to fix the cause first. We'll always tell you honestly whether the fix is paint or plumbing, and we'll refer you to a good damp surveyor if we spot signs of active moisture ingress.
Why homeowners choose our stain blocking team
The right sealer for the actual stain
Zinsser BIN, Cover Stain, Perma-White or specialist damp coating — matched to what's on the wall.
Permanent — no bleed-back
Sealed properly, the stain does not come back. Guaranteed on our workmanship.
Honest about paint vs. plumbing
We won't take money to paint over live damp. If it needs a plumber or damp surveyor, we'll say so.
Fast for insurance / claim work
Regular work with London insurance loss adjusters — reports and photos supplied.
How a typical stain blocking job runs
- 01
Identify the stain
Water, nicotine, smoke, biro, rust or efflorescence — each has a different sealer.
- 02
Check for live moisture
Moisture meter reading on damp stains — no sealing over an active leak.
- 03
Prepare
Loose paint scraped, mouldy areas treated with fungicidal wash, salts brushed off.
- 04
Apply the right sealer
One or two coats of Zinsser BIN / Cover Stain / Perma-White depending on stain type and area.
- 05
Redecorate
Full two-coat repaint over the sealed area, blended into the surrounding wall or ceiling.
Damp & Stain Blocking in your area
We cover all of Greater London. Popular areas for our stain blocking service include:
Damp & Stain Blocking questions, answered
Why does my ceiling stain keep coming back through the paint?+
Because emulsion is water-based, and most persistent stains (water, nicotine, biro, tannin) are pulled up through water. Every fresh coat of emulsion re-activates the stain and re-carries it to the surface. The only fix is a shellac or oil-based sealer between the stain and the emulsion. Zinsser BIN is our go-to.
Can you fix damp with paint?+
You can fix a stain from historic damp. You cannot fix live damp with paint — the water has to come out somewhere and it will always find its way through the film. Fix the source first; then we seal and repaint.
How much does stain blocking cost?+
A single water-damaged ceiling patch (sealed and repainted) is typically £150–£280. A whole nicotine-yellowed room (walls and ceilings sealed and repainted) £600–£1,100 depending on size.
What's the difference between Zinsser BIN and Cover Stain?+
BIN is shellac-based — fastest drying, best for tough stains (nicotine, water, biro, smoke). Cover Stain is oil-based — better for large areas of general staining or new timber knots. We pick per job.
Will the smell be a problem?+
Zinsser BIN smells for 30–60 minutes then it's gone. Cover Stain has a stronger solvent smell for 6–12 hours. We ventilate properly and warn you in advance.
Related services
Ready to book your stain blocking job?
Call for a chat, or send us the details and a couple of photos — you'll have a written quote the same working day.