ASTM F2326 — Visible Emissions & Smoke Testing

Standard Overview

ASTM F2326-04(2021) is titled "Standard Test Method for Collection and Analysis of Visible Emissions from Candles as They Burn." It is published by ASTM Committee F15, Subcommittee F15.45, in Book of Standards Volume 15.11, last updated February 9, 2021.

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Scope

This standard covers the collection and analysis of visible smoke emissions from indoor-use candles during burning, and enables comparison of relative smoke output across different candle designs and formulations.

• Not applicable to: multiple-wick candles, taper candles, and floating candles.

This is a development and comparison tool only. It does not set pass/fail criteria — no standard level of acceptable visible smoke is defined.

Significance & Use (Standard Sections 5.1–5.4)

• 5.1: To aid the candle manufacturer in optimizing formulations for the reduction of visible smoke emissions.
• 5.2: To provide a standard procedure during development for comparing relative smoke and burn behavior across formulations. Established protocol: trim wick to 6–7mm (¼ inch) prior to each burn cycle.
• 5.3: A relative ranking of formulations can be established using histograms of collected emission data and statistical control charts.
• 5.4: This method sets no standard level for visible smoke emissions. There is no pass/fail threshold.

Wick Trimming Protocol

The standard establishes a specific wick preparation requirement for every test cycle:

• Trim wick to exactly 6–7mm (¼ inch) before each burn cycle.
• Consistent trimming is essential for reproducible, comparable results across test runs.
• Choose a protocol (always trim vs. never trim) and apply it uniformly across all comparative tests.

Wick length is the single most impactful variable in smoke output testing. A longer wick produces a larger flame, more incomplete combustion, and more visible soot. Mushrooming dramatically increases emissions.

Applying F2326 in Your Testing Lab

How to incorporate this standard into your burn testing workflow:

• Before each cycle: Trim wick to ¼ inch, record exact length, document wax/fragrance/wick/container specs, and set a controlled environment (68–77°F, no drafts).
• During burn: Observe visible smoke every 30–60 minutes, photograph soot deposits on the jar interior, and note any mushrooming, flaring, or carbon buildup.
• After each cycle: Record post-burn wick condition, note soot on jar walls and lid, and measure any change in wick length.
• Comparative analysis: Run identical protocols across all formulations. Plot results to rank by emission level. Lower visible emissions indicate a cleaner, safer, higher-quality formulation.

Purchasing the Full Standard

ASTM F2326-04(2021) is a 5-page document available directly from ASTM International:

• Price: $72.00 USD (PDF, Hard Copy, or Online + Redline Bundle).
• ASTM Compass® subscribers can access it at no additional cost.
• Previous versions available: F2326-04R15, F2326-04R09, F2326-04.

Purchase at store.astm.org