Drying Time Recorders
QualiDTR™ Series – Paint & Coating Drying Stage Analysis
A drying time recorder also known as a Beck-Koller (BK) recorder measures the progressive stages of drying and curing in paint and coating films by drawing a hemispherical needle across a freshly applied wet film at a precisely controlled, constant speed. Because the speed is fixed and the track length is known, the position of the needle at any moment in time corresponds directly to the elapsed test time — allowing the stage at which the trace pattern changes to be read directly from the graduation scale on the glass panel. This elegant use of the relationship Distance = Speed × Time converts temporal information into a visible spatial record of the film’s drying history, without the need for an observer to be present at the exact moment of each drying stage transition.
The test distinguishes four primary stages of film drying. In the first stage, during solvent evaporation, the needle leaves a deep pear-shaped impression as it displaces the still-fluid paint. As the surface begins to skin over, the trace narrows to a fine drawn thread — indicating the surface dry or set-to-touch stage. Once the film becomes tack-free, the needle produces a powdery or crumbly trace that no longer sticks to the tip. In the final hard-dry stage, the needle leaves no visible mark. These four trace morphologies, read against the position graduation on the glass strip, directly yield the set-to-touch time, tack-free time, and hard-dry time — the three drying stage values reported in product data sheets and verified against specifications per ASTM D5895 and ISO 9117.
Know Exactly When Your Coating Is Ready
Drying time is not one number it is a profile of four stages that determines your coating’s re-coat window, its return-to-service interval, its pot-life on the substrate, and the claims you can make on your product data sheet. The QualiDTR Series gives you that complete profile in a single, unattended overnight run, at the precision and reproducibility that ASTM D5895 and ISO 9117 require. Whether you are qualifying a new alkyd formulation, confirming that an incoming resin lot dries within specification, comparing six experimental cure-rate modifications side-by-side, or generating the drying time data for a regulatory submission or OEM approval package, Qualitest has the instrument and the application expertise to support your program.
Contact Qualitest today to request a technical datasheet for the QualiDTR™-I or QualiDTR™-II, ask about Cube Applicator gap size options for your film thickness targets, or receive a quotation for the complete drying time test system.
