Caustic Soda

Caustic Soda is sodium hydroxide (NaOH) in pearl form — a powerful, corrosive chemical used to clear blocked drains and pipes, and to strip stubborn grease, paint and grime from concrete, brick and other hard surfaces. It's highly effective, but it's a serious hazard if handled carelessly — read this guide fully before use.

Before you start — this one matters

Corrosive. Causes severe skin burns and serious eye damage. Wear chemical-resistant gloves and eye/face protection at all times.
Always add caustic soda to water — never water to caustic soda. Adding water to the solid can cause a violent, splashing reaction.
Always use cold water. Dissolving caustic soda generates heat — the mixture will get hot.
Use a plastic bucket and stir with a wooden spoon or stick — not metal. Caustic soda reacts with many metals to release flammable hydrogen gas.
Do not use on aluminium, zinc, galvanised steel or acrylic surfaces — it reacts with these and can generate flammable gas.
Don't mix with any other chemicals.
Never pour neat, undissolved caustic soda directly into a drain — always dissolve it first.
Work in a well-ventilated area. Avoid breathing in dust when handling the pearls.
Full safety information is in the product's Safety Data Sheet — ask us if you need a copy.

How to use it

Always dissolve the pearls in cold water first, adding caustic soda to the water — never the other way round.

Blocked drains & pipes

Gradually add 250g caustic soda to 3L cold water in a plastic bucket, stirring gently with a wooden stick.
The solution will heat up — let it stand briefly if needed.
Pour immediately into the drain.
Leave for 20 minutes.
Flush with boiling water. Repeat if the blockage persists.

Concrete, brick & paved surfaces

Gradually add 125g caustic soda to 5L cold water in a plastic bucket, stirring gently with a wooden stick.
Pour onto the stained area and scrub with a brush.
Leave for around 20 minutes.
Rinse thoroughly with clean cold water. Repeat if necessary.
Take care when working near plants or grass — caustic soda will damage them.

Product details

Formats	2.5kg tub / 5kg / 25kg pearl
Composition	Sodium hydroxide (NaOH), high purity pearl
Classification	Corrosive — Skin Corrosion Cat 1, Serious Eye Damage Cat 1

Not suitable for: aluminium, zinc, galvanised steel or acrylic surfaces.

Before you start — this one matters

How to use it

Blocked drains & pipes

Concrete, brick & paved surfaces

Product details

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