Methyl methacrylate (CAS 80-62-6): storage and disposal

Dental acrylic liquid usually arrives as a small bottle sold alongside the matching powder, and the pair often end up together on a laboratory bench or in a surgery cupboard. That habit is the usual fault. The liquid gives off highly flammable vapour, so it belongs in a ventilated fire-resistant cabinet with spill containment, even when the powder stays elsewhere. Keep it clear of oxidisers and acids. Heat can set off polymerisation, which rules out a sunny windowsill or a shelf above a steriliser. Write the date of receipt and first opening on the label, because this monomer relies on date checks. Close the cap firmly after each use, as residue on the outside of a bottle is one way staff end up with an allergic skin reaction.

Age shows as thickening. Fresh monomer runs as easily as water. Once the inhibitor is used up or the bottle has been warmed, it turns syrupy, then gel-like, and can finally set into a plug of solid acrylic. Polymerisation gives off heat, so a bottle part way through may bulge or feel warm. Other things to look for are a level that has dropped through evaporation, a leaking seal and a tacky or stained label. It also belongs to the peroxide forming group, and any peroxide testing is for competent staff only. If the bottle is old, undated or shows any of these signs, do not move it, do not open it, and get a specialist assessment.

This can form peroxides as it ages, especially after opening. Age and the opened date matter more than appearance, so a container with no opened date should be treated as old.

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.

16 05 06* is the usual code when a college or university bottle leaves in a lab pack, while a dental practice or other human healthcare setting normally uses 18 01 06*. Tell us the volume, roughly how old it is and whether the liquid has thickened, since part polymerised stock is awkward to pack and the collector needs to know before arriving. If kits are being cleared, list the liquid and the powder separately because they are different wastes to describe. Following specialist assessment, the collector determines the appropriate packing and transport arrangements. Old, undated, thickened or otherwise suspect monomer must not be moved or opened before that assessment. Surgery sinks are never a route for the last few millilitres in a bottle, and the bottle should go as it is, with its label intact.

Usually held as: neat, dental acrylic liquid.

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.