Sourcing magnesium hydroxide from China

0% duty

Read from the UK Trade Tariff on 27 September 2026, heading 2816 covers hydroxide and peroxide of magnesium and oxides, hydroxides and peroxides of strontium or barium. All three leaves carried 0% on goods from China, with no anti-dumping measure, no registration and no suspension.

Magnesium oxide (magnesia) is covered in our magnesia and magnesite guide; confirm the commodity code.

Chemical rules

These are substances under UK REACH, so importers of one tonne or more a year need a registration position, and the safety data sheet and label follow the retained CLP Regulation (EC) No 1272/2008. Check the classification for barium and strontium compounds and for magnesium peroxide, an oxidiser, before selling them on.

Why cable makers buy it, and the food grade

Magnesium hydroxide works as a flame retardant because it breaks down to magnesium oxide and water when heated, absorbing heat and releasing water vapour, and it adds no halogens. That is why halogen-free, low-smoke cable compounds use it at high loadings, and why particle size and surface treatment decide whether the compound still extrudes well.

Food grade is sold as the additive E 528, so a food or supplement buyer needs a food-grade specification and a certificate of analysis for each lot, not the technical grade's data sheet.

Specifying magnesium hydroxide

Specify use and grade (flame retardant, environmental, food or pharmaceutical), Mg(OH)2 content, calcium, iron and chloride limits, median particle size and top cut, specific surface area, surface treatment for polymer compounding, whiteness, moisture, and packing in lined bags.

Worked duty example

An invented example rather than a quote: 20 tonnes of surface-treated magnesium hydroxide powder, commodity code 2816 10 00 00, bought for £11,000 free on board, with £1,500 of freight and insurance, so £12,500 is the value customs works from. No duty is due on magnesium hydroxide; import VAT at 20% of £12,500 is £2,500. If you are VAT-registered, that VAT is normally reclaimable. See calculating UK import duty and VAT for the method.

Inspection checklist

Analysis: check purity, impurities and particle size on the certificate, and verify a sample in an independent laboratory.

Performance: for flame retardant grades, compound a sample and check dispersion and flame test results.

Packing: check bag integrity, moisture, weight and lot marking.

What goes wrong

Magnesium hydroxide orders fail on particle size and treatment. Coarse or agglomerated powder disperses poorly, the surface treatment differs from the sample, iron content discolours compounds, and brucite-based grades are supplied against a precipitated grade order.

Test samples before shipping. See our quality inspection guide.

Cambridge China Bridge sources magnesium hydroxide for UK cable, plastics and water treatment buyers, checking the producer's lab first. See factory verification.

Related guides: Sourcing barytes and barite powder from China.