How to clean teak furniture: stains, wasps and restoring

Cleaning is the only maintenance teak really needs. Gloster says so itself: teak needs no special routine, just a thorough clean now and then (Gloster). But clean too hard, or with the wrong product, and you do more damage than the dirt ever would. This page covers the practical side: the routine clean, water marks, green algae, grease and wasps, and, further down, restoring teak that cleaning alone won’t fix. For the choice that comes after (let it go grey or protect it), see how to treat teak.

The routine clean

Outdoors, in season. Tribù advises first sweeping off loose dirt weekly with a soft hand brush, then cleaning with mild, pH-neutral soapy water and a microfibre cloth or sponge, along the grain (Tribù instructions). Gloster gives a thorough clean once or twice a year with water and a mild detergent, using a cloth, sponge or soft brush (Gloster).

Two practical tips from Tribù’s instructions: clean on a cloudy day or in the shade, and wait until the furniture has cooled down completely (Tribù instructions).

Soap or soda? The Dutch furniture company Hamilton Bay mentions a natural soap solution, warm water with soda, or soft soap (Hamilton Bay, Dutch). Always dilute soap (Souren Meubels, Dutch).

Deep cleaning with a teak cleaner

For a deep clean, for example in spring or before you apply a protector or sealer, Tribù and Gloster use a similar method (Tribù instructions, Gloster):

1. Protect yourself and your surroundings. Rubber gloves and eye protection (Gloster), and cover the ground. The Dutch furniture company Traditional Teak warns that cleaners can damage grass, plants and some paving (Traditional Teak, Dutch).
2. Brush off loose dirt with a hand brush, along the grain.
3. Wet the wood, for example with a plant sprayer.
4. Apply the cleaner and leave it to work briefly: Gloster gives three minutes, Tribù two to four. Keep the surface moist.
5. Scrub with a soft brush or the supplied brush pad, along the grain.
6. Rinse thoroughly with clean water and let it air-dry.

Planning to protect it afterwards? The wood must be bone dry, or according to the Dutch furniture company Hartman you can get discolouration or stains (Hartman, Dutch). Which product to choose is covered in teak oil vs sealer.

Water marks on teak

Water marks and rings come from spilt drinks, condensation from a glass or the base of a vase, according to the Dutch furniture company Van der Garde (Van der Garde, Dutch). How you remove them depends on the finish.

Untreated outdoor teak

Van der Garde advises wetting the whole table with the garden hose, scrubbing with soapy water or a teak cleaner and a brush, and then treating the whole table along the grain, not just the mark. Then rinse generously and let it dry evenly (Van der Garde, Dutch). If you only work on the mark, you end up with a pale patch.

Teak with a protector

Water marks on a table you treated six months to a year ago usually mean the protective layer has (partly) worn off. Van der Garde then has you remove the old layer by wet-scrubbing with a teak cleaner or soap, or by sanding lightly, and then treat it again (Van der Garde, Dutch).

Marks straight after treating

If it rains shortly after you apply a product, you can get water marks. Tribù therefore advises protecting treated furniture from rain for 24 hours, but not putting covers on it (Tribù instructions). If it happens anyway, Van der Garde says the whole protector layer has to come off: wet-scrub, rinse, and if that doesn’t work, sand lightly and treat again (Van der Garde, Dutch).

Indoor teak (dining table, coffee table)

The Dutch furniture companies Souren Meubels and Polder Teak give the same method, based on their own experience (Souren Meubels, Dutch, Polder Teak, Dutch):

1. Wipe it off straight away with a damp cloth and a little diluted soft soap.
2. Older than a day? Try soapy water with a scouring pad.
3. Still visible? Sand lightly with fine sandpaper, for example 220 grit. Teak is oily, so marks usually stay on the surface.
4. Sanded patch paler? According to both sources, it evens out over time.

On an oiled table, you then treat the sanded patch with oil a few times and the colour evens out. On a lacquered table that doesn’t work: Polder Teak says you then have to sand the whole top and lacquer it again (Polder Teak, Dutch). More on tables in teak table care.

Green algae and black dots

After a wet spell, green algae and moss can appear on teak. Souren makes up a bucket with 4 to 6 tablespoons of soda (soda crystals) and soft soap, washes the furniture, leaves it for 5 to 10 minutes, wipes it off with a sponge and rinses (Souren Meubels, Dutch).

Black or dark grey dots are usually not ingrained dirt but fungi and algae, according to Traditional Teak (Traditional Teak, Dutch). Vincent Sheppard names rainwater and tree sap as the cause and advises against placing furniture under trees (Vincent Sheppard). If teak has turned black from mould on old oil, Gloster says only aggressive sanding will remove it (Gloster); how to go about that is under restoring below.

If the furniture is evenly grey after cleaning and you want to keep it that way, read letting teak go grey.

Grease marks and oil on cushions

• Grease marks on the wood are natural and usually fade in the sun, according to Vincent Sheppard; it goes faster with a teak degreaser and a brush, followed by rinsing (Vincent Sheppard).
• Oil stains on cushions come from the teak itself, especially new wood. Vincent Sheppard advises letting leaked oil on a new piece dry outside for 24 to 48 hours before you put the cushions back (Vincent Sheppard). For the fabric, Gloster names an upholstery cleaner and, for stubborn stains, an oil soap (Gloster).

Wasps on your teak

Seeing wasps on your garden bench in spring, followed by pale, scraped patches? Gloster explains that wasps strip the surface of teak to build their nests, mainly from spring to early summer. The softer part of the grain on weathered teak is “the perfect material” for them (Gloster).

According to Gloster, there’s no real way to prevent it. The good news: it is cosmetic. See restoring for the repair.

Pressure washing teak

On this point all the sources agree: no pressure washer.

• Gloster: “under no circumstances” should a power washer be used; it erodes the soft surface and leaves it rough to the touch (Gloster).
• Tribù: no high-pressure cleaner or steam cleaner (Tribù instructions).
• Hartman: it creates small cracks in which dirt collects (Hartman, Dutch).
• Hamilton Bay: rougher patches can appear (Hamilton Bay, Dutch).

So you blast away the soft top layer, and according to Hartman dirt then collects in the cracks left behind. Use a garden hose or plant sprayer (Tribù) and a soft brush instead.

What else to avoid

• Wire brushes, stiff brushes or steel wool. According to Gloster these remove the softer part of the grain, and steel can leave rust spots in teak (Gloster).
• Abrasive sponges, “wonder” (melamine) sponges and caustic cleaners on outdoor teak (Tribù). Note: Hamilton Bay does mention a soft scouring pad, and indoors Souren Meubels and Polder Teak use one for stubborn marks. Outdoors, a soft brush is the safest choice (Tribù instructions, Hamilton Bay, Dutch).
• Bleach. Gloster: it discolours the wood (Gloster). Vincent Sheppard does mention a weak bleach solution for wine stains; that advice is deliberately left out here.

Restoring

Sometimes a clean isn’t enough. The wood is deep grey and rough, there are black patches, or stains and scratches won’t come out. Then it’s time to restore the piece. The rule: always start with the lightest intervention, and only sand if cleaning doesn’t work.

What do you see, and what do you do about it?

What you see	What it is	What to do
Evenly silver-grey, smooth	weathering; cosmetic, with no effect on quality or strength (Tribù)	nothing, or clean; see letting teak go grey
Grey and rough to the touch	raised grain	clean thoroughly, then sand lightly along the grain (Gloster)
Scratches or marks that won’t clean off	surface damage	sand them out with abrasive paper, along the grain (Gloster)
Pale, scraped patches in spring	wasps stripping fibres for their nests (Gloster)	cosmetic; sand lightly along the grain
Black wood after years of oil	mould on the oil at the surface	only removable by aggressive sanding (Gloster)
Dirt or mould deep in the wood, damaged surface	damage below the top layer	sand down to sound wood (Tribù instructions)
Water marks under a worn protector	the old layer has partly worn off	remove the whole layer by wet-scrubbing or light sanding, then treat again (Van der Garde, Dutch)
Hairline cracks	according to Hamilton Bay, a normal result of drying out (Hamilton Bay, Dutch)	usually nothing; see teak garden furniture care

The order, from light to heavy

1. Clean thoroughly first, as described above, and let it dry. Gloster has dirty or weathered teak cleaned with a teak cleaner first to remove all the stains (Gloster).
2. Still rough, or the stain is still there: sand. Always along the grain, never across it (Gloster). Light sanding removes raised grain. For damage that goes deeper, Tribù sands down to the unaffected layer, starting coarse with P80 and working gradually finer to P150–P220 (Tribù instructions). Wear a dust mask: teak contains substances that can cause skin complaints in sensitive people, according to the Dutch timber information centre Centrum Hout (Centrum Hout, Dutch).
3. Let the wood rest. Tribù leaves sanded wood untreated for one to two weeks before applying a protective product. For a sealer or protector on sanded wood, the same document gives two to three weeks (Tribù instructions). So allow at least a week, and read the label of your product.
4. Then choose: let it go grey or protect it. Sanded teak outdoors turns grey again. If you want to keep the colour, choose a sealer; which product suits you is covered in teak oil vs sealer. Don’t use varnish, linseed oil or teak oil outdoors: according to Tribù they can cause irreversible damage to the wood (Tribù instructions).

Not everyone agrees on that last point. The US site of furniture retailer Castlery, for example, recommends teak oil as a step when restoring outdoor teak (Castlery US). Its guide does not address the mildew risk that the manufacturers above warn about. That is why this guide follows the manufacturers.

Indoor furniture: check the finish first

• Oiled: treat a sanded patch with oil a few times and the colour evens out (Polder Teak, Dutch).
• Lacquered: spot repairs don’t work; Polder Teak then sands the whole top and lacquers it again (Polder Teak, Dutch).
• Veneered, like many older sideboards: the veneer is often thinner than a millimetre (about 1/25 in) and a belt sander goes through it in seconds (DIYguide.dk, Danish). So sand by hand and very lightly. How to recognise veneer is covered in vintage teak; for older pieces in general, see old teak.