Conical flask

The most critical factor is the material composition. You should prioritize Borosilicate Glass 3.3, which is the international standard for laboratory glassware due to its high thermal shock resistance and superior chemical durability. Ensure the glass is free of bubbles and streaks, and verify that it can withstand temperatures up to 500°C for sterilization and high-heat reactions.

Buyers must ensure products comply with ISO 1773 (Laboratory glassware — Narrow-necked boiling flasks) or ISO 4797 (Laboratory glassware — Flasks with conical ground joints). For volumetric accuracy, look for Class A or Class B graduation markings. If the flasks are intended for the US market, compliance with ASTM E1404 specifications is essential to ensure quality and safety standards are met.

Consider the neck type based on the usage scenario: Narrow neck flasks are ideal for swirling liquids to prevent splashing, while Wide neck flasks facilitate easier filling and cleaning. For titration or distillation setups, specify Standard Ground Joints (e.g., 24/29 or 29/32) to ensure airtight connections with other apparatus. Additionally, check for a reinforced rim to prevent chipping during frequent handling.

High-quality flasks use permanent enamel markings (usually white or blue) that are fired onto the glass. These markings should be acid and alkali resistant to prevent fading after repeated washing or exposure to corrosive chemicals. A large matte marking spot is also a vital feature for easy labeling and organization in a professional lab environment.

Glassware is highly fragile, so you must mandate 5-layer corrugated export cartons with individual bubble wrap or molded foam inserts for each flask. Request the supplier to use palletized shipping for bulk orders to minimize manual handling. It is highly recommended to purchase Marine/Cargo Insurance and include a 'Fragile' handling clause in the shipping contract.

Focus on sample consistency and batch testing reports. Before placing a bulk order, request a SGS or TUV third-party inspection to verify the strain point and annealing quality of the glass. For long-term partnerships, negotiate a breakage allowance (typically 2-3%) where the supplier provides extra units or credit for items damaged during shipping.

Always utilize the Secured Trading Service provided by Made-in-China.com to ensure your payment is only released after you confirm receipt and quality. Prioritize Audited Suppliers who have undergone on-site verification by independent inspection companies. This reduces the risk of dealing with trading companies posing as manufacturers.

Verify the HS Code (typically 701720) for laboratory glassware to determine the correct import duties in your country. Ensure the supplier provides a detailed Commercial Invoice, Packing List, and Certificate of Origin. Some regions may require a Declaration of Conformity to prove the glass does not contain hazardous lead or cadmium levels.