- 250 ml Borosilicate 3.3 evaporating flask
- Standard ground joint (29/32)
- 140 mm tall
- Low temperature gradient – can withstand high temperatures and thermal shocks*
- Superior chemical durability*
- Autoclavable at 121°C
OVERVIEW:
The GWSI Evaporating Flask is a 250 ml round-bottom vessel crowned with a 29/32 standard ground joint — a wide mouth on a small body, made for micro-batches and precious samples. The oversized opening lets you add solids, scrape out every last drop, and clean with ease, while the interchangeable ground joint seals air-tight on any 29/32 socket. Cut from premium borosilicate 3.3 glass, it handles fast heat-cool swings with high thermal shock resistance and stands up to steam and solvents with strong hydrolytic resistance. Chemical inertness protects your sample, it’s fully autoclavable lab glass, and it meets the same fit-and-finish bar as GWSI’s Class A and Class B volumetric glassware.
HISTORY:
When natural-product and medicinal chemistry went micro in the mid-1900s, chemists had a headache: their smallest flasks accepted only tiny joints, so they couldn’t hang a proper condenser or adapter off them. The wide 29/32 joint on a 100 ml body solved it — full-size glassware on a miniature vessel. That one pairing made it possible to reflux, distil, and evaporate single-digit-gram samples on the same rigs the big batches used.
APPLICATIONS:
– Pharmaceutical labs — evaporating trial batches and high-value intermediates.
– Biotech labs— drying down low-volume active fractions and assays.
– Industrial laboratories — method development and scale-up feasibility trials.
– Schools, colleges & universities — micro-scale organic synthesis in teaching labs.
– Research labs & educational institutes — precious-sample work were recovery matters most.
MANUFACTURING PROCESS:
GWSI melts high-purity borosilicate 3.3 tubing, blows each 250 ml body by master hand-blowing or automated molding, tool-grinds the 29/32 joint and fuses it to the neck by ceramic-glass fusing, then anneals every flask to relieve all thermal stress.
TESTING PROCESS:
Each flask gets a manual first inspection, then a polariscope polarization stress test for zero residual stress, ISO/DIN dimensional verification of joint and body on manual or automatic testing machines, plus NABL gravimetric calibration on volumetric items.
PRINTING PROCESS:
Markings are applied by precision screening with glass enamels and baked in high-temperature kilns to permanently fuse the scale into the glass matrix, so it never fades.
PACKAGING PROCESS:
Finished flasks pass cosmetic sorting to filter out blemishes, then ship in heavy-duty double-wall boxes with shock-absorbing bubble wrap for safe export.
MAINTENANCE & SAFETY:
– Rinse promptly with solvent or warm detergent; the wide neck gives full brush access to the 100 ml body.
– Grease the 29/32 joint lightly and release vacuum before pulling the flask off.
– Autoclave at 121 °C and cool gradually; sudden temperature jumps crack small flasks fast.
– Store upright with the joint capped so the ground surface stays protected.