Flat Weighing Bottles with Ground Covers

A weighing bottle exists to weigh a solid sample accurately when that solid would otherwise pick up or lose moisture in the open air. Its close-fitting ground-glass cover seals the sample so its mass does not change between the moment it is weighed and the moment it is used, which is essential for gravimetric (mass-based) analysis.

The low, flat form gives a large opening for adding and removing solid and a stable, easy-to-handle shape on the balance, while the ground lid keeps hygroscopic or volatile samples protected.

Gravimetric analysis, weighing hygroscopic solids, drying and loss-on-drying (LOD) tests, moisture determination, and storing samples for weighing, in analytical, QC, pharma, food-testing and teaching labs.

A low borosilicate 3.3 bottle (tall or squat forms) with a wide ground-glass joint and a matched flat ground cover that seals against moisture exchange. The cover is matched to its bottle. The glass is oven-dryable so the bottle and sample can be dried to constant mass.

Handle weighing bottles with tongs or tissue, not bare fingers, so skin oils and moisture do not change the mass. Dry the bottle, cool it in a desiccator, then weigh — repeating to constant mass for accurate work. Keep the matched cover with its own bottle. The ground joint should seal well to protect hygroscopic samples between weighings.

Formed from borosilicate 3.3 with a wide mouth, then the joint and cover are precision-ground to a close matched fit, and the set is numbered. Annealed for stress relief. Joint fit (for a good seal) and a stable, easy-to-handle form are the key checks.