Conical flask with grind

Ground Glass Joint Conical Flasks for Advanced Laboratory Setups

You know how frustrating it is when you're running a synthesis and your connections start leaking? Ground glass joint conical flasks solve that problem completely. They've got the familiar Erlenmeyer shape we all love—that wide, stable base and narrow neck—but with precisely machined ground glass joints that create vacuum-tight seals every time.

I've been using these for years in organic prep work, and honestly, once you switch from regular flasks, you won't go back. The joint fits perfectly with Condensers and other modular glassware, so you can build complete distillation or reflux setups without worrying about vapor escape.

Standard Taper Joint Specifications

The ground glass joints follow standardized taper sizes—you'll typically see 14/20, 19/22, or 24/40 designations. That first number is the joint diameter in millimeters, and the second is the length. Made from borosilicate 3.3 glass, these joints are machined to tolerances of ±0.05mm, which means they're interchangeable across manufacturers.

• Thermal shock resistance up to 500°C for demanding applications
• Permanent volume graduations molded into the glass
• Fire-polished rims prevent chipping and ensure smooth sealing
• Available from 25ml to 2000ml capacities

Vacuum-Tight Connection Advantages

Unlike a Conical flask with thread and polypropylene cap which works fine for storage, ground glass joints let you connect directly to a Straight tube condenser or other apparatus without adapters. You're creating a sealed system that can handle vacuum distillations, inert atmosphere reactions, or reflux operations where you absolutely can't have leaks.

I'll use these instead of a Conical flask with a narrow throat when I need modular connections. The narrow throat version is great for pouring and reducing evaporation during storage, but it won't give you that standardized joint interface.

Integration with Reflux and Distillation Apparatus

Setting up a reflux is dead simple—just pop your condenser onto the joint, maybe add a thin layer of vacuum grease if you're being extra careful, and you're good to go. The conical shape gives you excellent mixing efficiency with magnetic stirrers, and that wide base keeps everything stable on your hotplate.

For everyday mixing and storage where you don't need the joint, grab some Laboratory glasses and beakers instead. But when you're building reaction setups or doing anything under controlled atmosphere, ground glass joints are non-negotiable. They're autoclavable, dishwasher safe, and they'll last forever if you don't drop them.