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Chemical collection and stock control for UK schools, universities and hospitals

Magnesium ribbon (CAS 7439-95-4): storage and disposal

Every school prep room has a reel or coil of magnesium ribbon, and some also hold the powder. It is classified as a flammable solid that releases flammable gas on contact with water. Powder is the greater hazard, and a spill of ribbon offcuts or dust in a tidy-up is easy to underestimate.

CAS number
7439-95-4
Form
Solid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable

What to do this week

  1. Check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as flammable stock and apart from the items listed under "Do not store with".
  3. If you no longer need it, add it to your disposal list so it goes on the next collection.

Safe storage in a school or lab

Picric acid and Bouin's fluid are the surprising entries on the list of things to separate it from, since picric acid forms shock sensitive metal picrates with metals. Magnesium also stays apart from bromine, iodine, calcium hypochlorite, chromium trioxide, hydrogen peroxide and ammonium picrate, because strong reactive chemicals like these can form mixtures that burn fiercely or explode. Keep ribbon and powder in a dry, ventilated fire-resistant cabinet, in tightly closed containers, away from any water. Hold the powder separately from the ribbon, because it is the more hazardous form. A school store usually has a coil and offcuts in one jar, which is fine.

How to tell it has deteriorated

A dull grey oxide layer on the ribbon is normal, and it does not mean the stock has failed. Over many years the coil may look tarnished or powdery along its length. What matters more is the container: damp, corrosion at the lid, white deposits at the bottom of the jar or a swollen cap point to moisture. Powder that has clumped or caked has been exposed. Offcuts mixed with unlabelled residue from experiments make the jar mixed stock. An unreadable label counts as unknown stock and should be recorded.

How it must be disposed of

By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a flammable laboratory pack with compatible chemicals.

Specialist collection is the route for both ribbon and powder, and each form is recorded separately with its quantity. Burning magnesium cannot be put out with water or carbon dioxide, so no one should try to burn off surplus or dispose of it by reaction. It must not go in a bin, a sink or a skip. The inorganic chemical variant of the waste code applies outside a lab pack. The carrier packs it dry, away from picric acid, bromine and water, and treats the powder with more care than the ribbon.

Waste codes and transport details for Magnesium ribbon
EWC code, laboratory chemicals16 05 06*
Discarded inorganic chemical, not a laboratory pack16 05 07*
Hazardous wasteYes

The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.

Do not store with

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • CorrosiveA leak of corrosive stock can break down flammable containers and feed a fire.

Named chemicals to keep apart

  • Acetic acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Ammonium picratePicric acid forms shock sensitive metal picrates with metals.
  • BromineBromine reacts violently with ammonia, reactive metals and many solvents.
  • Calcium hypochloriteStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Chromium trioxideStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxideStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • IodineIodine forms sensitive or violently reacting products with ammonia and reactive metals.
Show 13 more
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Picric acidPicric acid forms shock sensitive metal picrates with metals.
  • Potassium chlorateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Potassium dichromateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
  • Potassium permanganateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Silver nitrateSilver nitrate can form explosive silver compounds with these materials.
  • Sodium azideAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
  • Sodium chlorateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Sodium dichromateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Thionyl chlorideA leak of corrosive stock can break down flammable containers and feed a fire.
  • Zinc chlorideA leak of corrosive stock can break down flammable containers and feed a fire.

Common quantities we collect

Usually held as: ribbon, powder.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.

Where it is commonly held

Hazard statements

  • H228 Flammable solid.
  • H261 In contact with water releases flammable gases.
Precautionary statements
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P222 Do not allow contact with air.
  • P223 Do not allow contact with water.
  • P231 Handle and store contents under inert gas.
  • P231+P232 Handle and store contents under inert gas. Protect from moisture.
  • P233 Keep container tightly closed.
  • P235 Keep cool.
  • P240 Ground and bond container and receiving equipment.
  • P241 Use explosion-proof electrical, ventilating and lighting equipment.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P302+P335+P334 IF ON SKIN: Brush off loose particles from skin. Immerse in cool water or wrap in wet bandages.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P402+P404 Store in a dry place. Store in a closed container.
  • P407 Maintain air gap between stacks or pallets.
  • P410 Protect from sunlight.
  • P413 Store bulk masses above the specified quantity at temperatures as specified on the label.
  • P420 Store separately.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.

Substance as classified, dilutions may differ.

Questions

Is a dull magnesium ribbon coil still usable?

A dull oxide layer is normal and does not necessarily make magnesium ribbon unusable. Whether it remains suitable for a particular experiment depends on its condition and the experiment's requirements. Unwanted ribbon is collected as chemical waste rather than put in a general waste bin.

Why is the powder treated differently from the ribbon?

The powder is more hazardous than the ribbon, with a larger surface area and a greater fire risk. Keep it in its own tightly closed container, away from water.

Which water-based stock should be kept away from it?

Anything wet, since contact with water releases flammable gas. In particular keep hydrogen peroxide, bromine and iodine away from it, and keep picric acid products on another shelf.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula Mg. EC number 231-104-6.

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