Reagent label maker

What belongs on a reagent label

A reagent that lives on a shelf is read by people who did not make it, often months later. The identity has to be unambiguous — “Tris” is not a reagent, “Tris-HCl 1 M pH 8.0” is — and the preparation date matters more than the expiry, because an undated bottle cannot be judged at all.

In the United States, a container of a hazardous chemical that is not in the original manufacturer's packaging is a workplace label under OSHA's Hazard Communication Standard, 29 CFR 1910.1200(f)(6). That rule accepts either the full GHS label elements or, as an alternative, the product identifier plus words, pictures or symbols that convey at least general information about the hazards. The editor's hazard tools cover both routes.

Where a reagent is transferred for immediate use by the person who made it and stays under their control for that shift, the standard's portable-container exemption applies and no label is required. Almost nothing on a shelf meets that description.

The five fields that earn their space

Identity, in full

Salt form, concentration and pH if it has one. “PBS” is fine; “PBS pH 7.4, 1×” is better, because the 10× stock looks identical.

Prepared date

Not the expiry. An expiry is a judgement that depends on storage; a preparation date is a fact, and anyone can apply their own judgement to it.

Who prepared it

Initials are enough. This is the field that turns “is this still good?” into a question someone can actually answer.

Storage condition

Only where it is not obvious. “4 °C” on a fridge bottle is noise; “room temperature” on something people assume is refrigerated is not.

Hazard information

Signal word and pictograms where the reagent is hazardous. On a 50 × 25 mm label, two pictograms and a signal word fit alongside three lines of text.

How much text fits on this label

Solvent exposure decides the material, not the printer

Reagent labels get wiped with ethanol far more often than they get frozen. Direct thermal labels — the kind a Dymo LabelWriter prints, with no ribbon — darken with heat and lift with solvent, and a wipe with 70% ethanol can take the print off entirely.

Laser toner on a polyester or polypropylene label is fused plastic on plastic and survives ethanol and isopropanol well. Thermal transfer with a resin ribbon on polyester is the most robust of the three. Inkjet dye on paper is the least: it runs on contact with almost anything wet.