Viscosity measurement by bubble method is suitable for viscosity determination of transparent liquids such as paints, resin solutions and varnishes. The bubble viscometer is composed of a group of glass tubes of the same specification filled with different viscosities, colorless and transparent mineral oil, and the rising time (g) and kinematic viscosity (cmZ/g) of the bubbles in the tube are measured in advance. Standards arranged in increasing order. Its characteristic is that it can give accurate viscosity data in a short time, so it is mostly used in the intermediate control of the coating production process. Due to the different specifications of the bubble viscometer, the Gardner tube method and the ASTM tube method are introduced below.
The determination of the bubble load meter can use the comparison method or the timing method. The comparison method is also called the alphabetical comparison method. The standard reference glass tube with letters divided into four groups is compared with the sample to obtain the viscosity of the sample. The timing method is also called the direct time method. A glass test tube engraved with a "time line" is used to measure the "bubble second", that is, the time required for a bubble to vertically pass through a known distance in a glass tube of known diameter.
The ASTM pipe method compares the sample with a standard pipe of known viscosity to find the closest standard pipe number to indicate the viscosity. The timing method uses a glass tube engraved with 3 "time lines" to measure the time for a bubble to rise vertically for a certain distance in a glass tube of known diameter, expressed in seconds.
