The Antique Glass Checklist: What to Inspect Before You Buy
Antique glass can conceal chips, cracks and chemical deterioration that are difficult to see in ordinary shop lighting. A careful examination should protect the object while revealing how it was made and altered.
Handle as little as possible
Ask permission before touching. Remove rings and support the object from beneath with both hands. Never lift a vessel by its rim, stem or handle, and keep lids separate during inspection.
Use several lighting angles
View against both light and dark backgrounds. Use raking and transmitted light without placing the glass against a hot lamp. Rotate the object by moving its padded support when possible.
Look for:
- Rim and foot chips
- Star cracks and bruises
- Cracks around handles
- Ground-down rims
- Polished chips
- Scratches and internal staining
- Adhesive joins and replacement parts
- Later engraving
- Cloudiness, iridescence or surface flaking
Understand manufacture evidence
Bubbles, tool marks, mould seams and pontil evidence can support identification, but none dates an object by itself. Compare form, colour, weight, technique and decoration with documented examples.
Watch for unstable glass
Persistent surface moisture may be "weeping," while fine networks of cracks and haze may indicate "crizzling." The [Canadian Conservation Institute](https://www.canada.ca/en/conservation-institute/services/preventive-conservation/guidelines-collections/ceramics-glass-preventive-conservation.html) warns that severely deteriorated glass can develop fragile, flaking surface layers.
Do not assume cloudiness will wash away. Cleaning unstable glass may accelerate damage.
Check restoration
Adhesive can yellow, collect dirt or fail. Ask whether cracks, rims, handles, stoppers or feet have been repaired or replaced. Compare colour and ultraviolet response only as part of a broader expert examination.
Confirm all components
For decanters, jars and covered vessels, check that stoppers and lids fit without strain and match in colour, wear and technique. A period replacement may be acceptable, but it should be disclosed.
Ask about provenance and attribution
Factory marks on glass are less universal than on ceramics. Labels and signatures can be forged or transferred. Request evidence supporting a claimed maker, designer or date and preserve original labels.
Plan display
Use stable shelving, suitable supports and clearance from edges. Avoid direct sun and rapid temperature changes. Do not use important antique glass for food or drink without appropriate assessment.
For a costly or chemically unstable piece, consult a glass specialist or conservator before purchase.
For restoration demonstrations and workshop stories, [watch and subscribe to Antique Repair Shop on YouTube](https://www.youtube.com/@AntiqueRepairShop).
Sources and further reading
- [Canadian Conservation Institute: Caring for ceramic and glass objects](https://www.canada.ca/en/conservation-institute/services/preventive-conservation/guidelines-collections/ceramics-glass-preventive-conservation.html)
- [LAPADA: Art and antiques categories](https://lapada.org/art-and-antiques/)
- [CINOA: Code of Ethics](https://www.cinoa.org/about/code-of-ethics/)