Cleaning technique does more to determine how long glassware lasts than the brand on the box. It is also the cheapest quality control available on any bench: a vessel that is genuinely clean removes an entire category of unexplained result.
Clean immediately, not eventually
The single most useful habit is rinsing straight after use, while whatever was in the vessel is still soluble. Dried protein, cured resin and precipitated salt all take far harsher treatment to remove than the same material would have needed wet — and it is the harsh treatment that damages the glass.
Use the right detergent, at the right dilution
Laboratory-grade detergents are formulated to rinse away completely. Domestic washing-up liquid is not: it contains conditioners designed to leave a film, and that film is exactly what you do not want on the inside of a reaction vessel. Follow the stated dilution. Over-concentrated detergent is not more effective — it simply leaves a residue of its own, which interferes with subsequent work more than the soil it replaced.
What not to reach for
- Abrasives. Scouring powder, wire wool and stiff metal brushes all scratch. Use a soft brush sized to the vessel.
- Chromic acid, unless your protocol specifically requires it. It works, and it is hazardous waste with a disposal cost and a real risk attached.
- Sudden temperature changes. Filling a hot vessel with cold water is the most common self-inflicted breakage in any laboratory.
Rinsing, and how to tell when you are done
Rinse several times with tap water, then two or three times with deionised water. The test is simple and old: water should sheet evenly off the inside surface. If it beads, something hydrophobic is still there and the vessel is not clean, whatever it looks like.
Drying and storage
Invert on a rack and let it drain. Where a piece must be dry quickly, an oven at a moderate temperature is fine for most glassware but not for volumetric ware — repeated oven drying will, over time, shift a Class A flask outside its tolerance, and the tolerance was the reason you bought it. Air-dry volumetric ware.
Store where pieces are not touching. Glass against glass on a shelf chips at the rims, and a chipped rim is where cuts come from.