表干時間
表干時間
表干時間，單組份室溫硫化硅橡膠暴露在大氣環境里固化過程中，用手指觸摸表面，黏性消失，不黏手的時間，具體應用時候應指出環境溫度。
英文：tack free time，簡稱：TFT
測定方法原理：在規定條件下將密封材料試樣填充到規定形狀的模框中，用在試樣表面放置薄膜或者指接觸的方法測量其乾燥程度。報告薄膜或手指上無粘附試樣所需要的時間。
詳細可以參考GB/T 13477.5-2002 建築密封材料試驗方法 第5部分：表干時間的測定
The time period during which a sealant that is molded in the field remains tacky and is not yet fully serviceable. The tack-free time is a measure of the surface cure time and may generally be correlated to a variety of useful parameters such as the time interval before the sealant
(1) resists damage by touch or light surface contact,
(2) resists job-site or airborne dirt pick-up
(3) resists impinging rainfall.
The tack-free time is sometimes used as an on-the-job quality assurance test. A quality product that is consistent and reproducible will generally fall within a maximum and minimum tack-free time.
This test for tack-free time can be used at any temperature and humidity. It is important that if a sealant will be used in a climate quite different than the standard conditions called out in this test method, then those conditions be used to test the sealant.