Mastering Dolly Adhesion Testing: A Step-by-Step Guide

Mastering Dolly Adhesion Testing: A Step-by-Step Guide

The Dolly adhesion test is the measurement of coating adhesion strength, usually used to evaluate the bonding strength of coating and substrate. The main purpose of dolly adhesion test is to ensure that the coating is firmly bonded to the substrate to provide long-lasting coating protection and to ensure that the coating will not peel, flake, or crack during use.

Dolly adhesion test can be carried out before, during, and after the construction of the paint. Before construction, you can check whether the preparation of the substrate surface is sufficient to ensure that the coating is firmly bonded to the substrate. During the construction, the construction quality of the coating can be checked, and the parameters of the coating can be adjusted in time to ensure that the adhesion of the coating meets the requirements. After construction, the coating can be inspected and evaluated to ensure the quality and service life of the coating.

Use standard test methods, such as ASTM, ISO, etc. The specific test method varies depending on factors such as coating type, substrate type, and application requirements.

Pull-off method adhesion tester test process:

The test sample or system is applied in a uniform thickness to a flat plate with a uniform surface structure.

After the coating system has dried/cured, the test post is bonded directly to the coated surface with a special adhesive.

After the adhesive is cured, put the bonded test combination on the BGD500 tester. The tester pulls the test column from the coating uniformly and at a speed not exceeding 1MPa/s through the hydraulic pump, and the required force passes through the liquid crystal of the instrument. The screen is displayed directly to measure the force required to break the coating/substrate adhesion.

It is worth noting that the test results are expressed by the tensile force between the failure interfaces (adhesive failure) or the tensile force of self-destruction (cohesive failure), and the adhesion/cohesive failure may occur simultaneously.

Instructions for use of pull-off adhesion tester:

There are currently three main methods for testing the adhesion between the coating and the substrate: one is the circle method, the other is cross-cut method, and the other is the pull-off method. Both the circle method and the cross-cut method can only grade and divide the adhesion, but cannot be quantified; while the pull-off method can quantitatively (in Mpa) describe the specific size of the adhesion, which is useful for comparing the adhesion of different coatings. Effective, and very suitable for R&D personnel to use when developing formulas.

LR-P6, LR-P10 is an intelligent adhesion testing instrument newly developed by our company with reference to similar foreign products. It uses hydraulic pressure to perform a pull-off test on a specific area of the coating, and the pull-off force can be displayed on a digital display.

The instrument has the characteristics of simple operation, low cost of data, maintenance, and supporting consumables. The instrument has a USB interface, which itself is equivalent to a U disk. After connecting to the computer through the data cable, the operator can directly export all the test data.

The instrument is widely used in some concrete base coatings, anti-corrosion coatings, or adhesion tests between different coatings in a multi-coating system.

Adhesion test standard:

■ISO4624 “Paints and varnishes-Pull-off test for adhesion”

■ASTMD4541 “Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers”

■ASTMD7234 “StandardTestMethod for Pull-OffAdhesionStrengthofCoatingsonConcreteUsingPortablePull-OffAdhesionTesters”

■GB/T5210 “Paint and varnish pull-off adhesion test”

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