Begin with the use, then choose the glass
For stackable tumblers, send the target capacity, rim diameter, base diameter and stacking height. For a teapot or carafe, add the hottest liquid and the coldest surface it will meet. A high borosilicate glass factory and a soda-lime glass factory may quote the same silhouette for different uses. Ask each to identify the formulation and the test conditions behind any thermal-use claim.
Separate material from treatment
Tempering describes a treatment, not a glass composition. When comparing tempered glass, ask which parts receive the treatment and how breakage is evaluated. For pressed patterns, check mould seams on a physical sample. For stemware, inspect the stem joint, rim finish and how the base sits on a flat surface. Lead-free crystal glass is an option to discuss for clarity and cut patterns. Keep leaded crystal proposals in the decorative, non-food-contact range.
Turn the sample into an inspection reference
Mark a fill line on a sample tumbler and measure its actual capacity. Record the agreed tolerances for weight and wall thickness, then photograph the approved rim and base. Ask for one packed pair as well as a loose sample: compare the dividers, glass-to-glass clearance and any rubbing after transit. These details let purchasing and quality teams inspect against the same reference.
Include in your enquiry
- Target use, destination and temperature conditions
- Glass composition, forming method, decoration and any tempering
- Dimensions, fill capacity, acceptable variation and carton layout