Method for determining the viscosity of paints

The viscosity of the coating is also called the consistency of the coating, which refers to the fluid itself has adhesion and produces a kind of characteristic that prevents its relative flow inside the fluid.This index basically controls the consistency of coating, accord with use requirement, its affect construction performance, paint film flow level sex directly, flow hangs a sex.Through determination viscosity, can observe coating to store the polymerization degree after a period of time, according to different construction requirements, adjust viscosity with suitable diluent, in order to achieve brush besmear, gas, gas spraying required different viscosity index.

Method for determining the viscosity of paints

The national standard CB/T 1723-93 provides three methods for measuring viscosity, including coating -1, coating -4 viscosity cup and falling ball viscometer determination of coating viscosity, the most commonly used determination method is coating -4 viscosity cup determination method.This method is simple and easy to use, that is, 100mL of paint liquid is discharged from the aperture with a diameter of 4mm at a specified temperature, and the time is recorded, denoted by S, which is to measure the viscosity of the paint sample.

Method for determining the viscosity of paints

Pay attention to measurement

(1) The specified temperature should be between 21~25C.Because the temperature is too high, the viscosity is thin, the temperature is too low, the viscosity is thick, not the standard value.

(2) after each test to clean the coating -4 cups, choose the corresponding solvent of the coating, to prevent the determination of holes blocked.

(3) first use fingers or instruments to plug the small hole leak, pour 100mL paint, with a glass rod will bubble and excess samples into the groove, to prevent the test sample is less than or more than the standard.

(4) When the finger is quickly removed, start the stopwatch at the same time, and stop the stopwatch immediately when the sample flow beam is just interrupted.

The empirical method for measuring the viscosity of paint products is to observe the paint by stirring it with a stick.Normal coating should fall freely and ceaseless, if have interrupt and retraction phenomenon, explain this coating thicker.Generally, the paint on the rod and the paint in the bucket will be connected in a very short period of time, and the connection distance is 30~ 50cm, which is close to the degree of brush coating.Less than 30cm, that the viscosity of the coating is too small, that is, the coating is too thin;Greater than 50cm, show viscosity is too big, namely coating is too thick.This is in accordance with the construction requirements, but also through many practical applications, viscosity measured without viscometer, known as working viscosity.

Tu – 4 cup of viscosity measuring method is most commonly used, paint viscosity value between 40 ~ 150 s, but thixotropic coating using this method the measured viscosity is too big, need a rotational viscometer, paddle rotating viscometer, coaxial barrel rotary viscosimeter, cone plate viscometer, such as the architectural coatings viscosity determination using, tow’s viscometer (a) of the rotational viscometer method,The viscosity measured at this time is the load required to produce 200r/ min speed, expressed in g or KU.

When adjusting coating viscosity, appropriate thinner should be added as appropriate, and mechanical agitation should be used to make coating uniform up and down.Diluent dosage does not exceed 5% of coating total quality commonly, and the coating that uses high-pressure without gas spraying construction — do not add diluent like.