ASTM C679-15 (2022) PDF

Full title and description

Designation: ASTM C679-15 (Reapproved 2022) — Standard Test Method for Tack‑Free Time of Elastomeric Sealants. This method defines a laboratory procedure to determine the tack‑free (surface cure) time of single‑ and multi‑component elastomeric sealants used for caulking and glazing in building construction.

Abstract

ASTM C679 specifies a simple, repeatable test using a polyethylene film and a 30 g weight to determine when a curing elastomeric sealant no longer transfers bulk material to the film (the tack‑free end point). The result is a measure of surface cure useful for quality control and on‑site evaluation of sealant performance.

General information

• Status: Active (C679‑15 reapproved 2022).
• Publication date: January 1, 2022.
• Publisher: ASTM International.
• ICS / categories: 83.060 (Rubber); 91.100.50 (Binders; sealing materials).
• Edition / version: C679‑15 (originally approved 2015; reapproved 2022).
• Number of pages: 3 pages.

Scope

This test method covers determination of the tack‑free time of self‑leveling and non‑sag grades of elastomeric sealants, including one‑part and multi‑component products (and those requiring slight heating for extrusion). The procedure measures the elapsed time from application until the sealant no longer transfers bulk material to a polyethylene test film when a 30 g weight is applied for 30 s. It is intended for laboratory and on‑site quality checks and does not address all possible safety considerations or field variables.

Key topics and requirements

• Definition of tack‑free time (surface cure end point) and interpretation guidance (ignore very thin transfer or plasticizer film when determining end point).
• Required apparatus: controlled environment cabinet/room, 30 g rectangular weight, polyethylene strips (approx. 127 × 25 × 0.15 mm), timer, and non‑porous plates for specimen preparation.
• Specimen preparation and testing intervals (including pre‑test procedures when relative tack‑free time is unknown).
• Applicable material types: non‑sag and self‑leveling elastomeric sealants, single‑ and multi‑component formulations, and those slightly heated for extrusion.
• Significance and use: correlation of tack‑free time with resistance to touch damage, dirt pick‑up, and early rain exposure; used for quality assurance and product comparison.
• Reference to related ASTM terminology and material specifications (see referenced standards).

Typical use and users

Used by materials and quality laboratories, sealant manufacturers, product development teams, construction quality‑assurance personnel, specifiers, and contractors. Typical applications include product development, batch QA, comparative testing, and on‑site checks to assess cure progress before exposure to traffic or weather.

Related standards

Commonly referenced/related ASTM standards include C717 (Terminology of Building Seals and Sealants), C920 (Specification for Elastomeric Joint Sealants), and other C24 committee test methods and specifications for sealant performance and terminology. These documents provide complementary definitions, performance requirements, and broader product specifications.

Keywords

tack‑free time, elastomeric sealant, surface cure, caulking, glazing, test method, polyethylene film, non‑sag, self‑leveling, ASTM C679.

FAQ

Q: What is this standard?

A: ASTM C679‑15 (Reapproved 2022) is a standard test method that specifies how to measure the tack‑free (surface cure) time of elastomeric sealants used in building caulking and glazing.

Q: What does it cover?

A: It covers specimen preparation, required apparatus, test procedure using a polyethylene film and 30 g weight, end‑point interpretation, and the scope of applicable sealant types (self‑leveling, non‑sag, one‑ and multi‑component, and certain heat‑assist formulations).

Q: Who typically uses it?

A: Manufacturers, independent test laboratories, construction QA staff, architects and specifiers, and contractors who need to evaluate cure behavior or perform quality control on sealant products.

Q: Is it current or superseded?

A: The C679‑15 edition was reapproved in 2022 and is current as of the 2022 reapproval date; it is the active test method edition described as C679‑15 (Reapproved 2022).

Q: Is it part of a series?

A: Yes. C679 is maintained by ASTM Committee C24 on Building Seals and Sealants and sits within a family of C24 test methods and specifications (for example, C717 terminology and C920 sealant specifications) that collectively address sealant properties, performance, and definitions.

Q: What are the key keywords?

A: Tack‑free time, elastomeric sealant, surface cure, caulking, glazing, test method, polyethylene film, non‑sag, self‑leveling.