Procurement FAQ Frequently Asked Questions by Global Buyers
Technical clarity for international sourcing managers, brand founders, and quality assurance teams.
How do you calculate burn rate and scent throw efficiency for wholesale glass jar candles?
Burn rate is determined by measuring total mass loss (grams per hour) during consecutive 4-hour test burn cycles inside draft-regulated testing chambers (21°C–23°C ambient temperature). Scent throw efficiency is divided into cold throw (fragrance volatilization at room temperature) and hot throw (aroma diffusion from the molten wax pool). Hot throw depends on generating a uniform molten wax pool across the entire container diameter within 2 to 3 hours, achieving an optimal pool depth of 6mm to 10mm without overheating the glass jar container walls.
What causes candle tunneling or soot production, and how does factory engineering prevent it?
Tunneling occurs when a wick's heat output is insufficient relative to the glass jar’s diameter, or when the wax blend's melting point is too high. Soot production stems from incomplete combustion caused by oversized wicks, off-center wick positioning, or excessive oil loading that over-saturates the wick core. At Shanghai Qusden Household Products Co., Ltd., we prevent these flaws by using custom-braided lead-free cotton or zinc-free paper-core wicks, centering wicks with precision automated guides during pouring, and balancing fragrance loading (6%–12%) against wax density.
What are the key shipping and safety protocols for bulk glass jar candle ocean freight?
Glass jar candles must withstand thermal shock and mechanical vibration during cross-border transit. We utilize annealed soda-lime glass containers designed to withstand abrupt temperature shifts. Master packaging includes heavy-duty corrugated cartons fitted with custom honeycomb dividers or high-density EVA foam trays. Desiccant packets are placed in every export box to prevent humidity crystallization, and pallets are stretch-wrapped and corner-boarded to meet ISTA transport safety standards.
What is the standard lead time and MOQ for OEM private-label glass jar candles?
Our standard Minimum Order Quantity (MOQ) ranges from 600 to 1,000 units per style, depending on vessel processing (e.g., custom color spraying, screen printing, or hot foil stamping). Production lead times generally require 25 to 35 business days after final pre-production sample approval, safety burn testing verification, and packaging design confirmation.
How does Shanghai Qusden test packaging for zero-breakage international transit?
We conduct extensive pre-shipment quality assurance inside our internal testing laboratory. Every batch undergoes transportation vibration testing on automated shake tables, thermal stability tests inside constant temperature and humidity incubators (ranging from -15°C to +50°C), and vacuum oven testing to verify container seals and wax adhesion before authorizing bulk container loading.
