Reference method for measuring the surface tension of chromium electroplating: chapter 1

1. Introduction

This Reference Method describes the procedure for determining the surface tension of chromium electroplating, chromium anodizing or reverse etching solutions, using a 2.5 mL or a 5 mL stalagmometer.

Surface tension, with respect to liquids such as water or chromium electroplating, chromium anodizing or reverse etching solutions, is a result of the stronger interactive molecular forces which exist between molecules in the interior of a liquid than the molecular force which exists on the molecules at the immediate surface of the liquid. This force imbalance is due to the lower number of molecules located immediately above the surface of the solution. This resultant force imbalance causes the molecules at the surface of the solution to be pulled towards the molecules in the liquid.

Surface tension is force acting over a length, which is measured in dynes/cm (dyn/cm) or milli Newtons/metre (mN/m).  These units are equivalent.

Measurement of the surface tension of a chromium electroplating, chromium anodizing or reverse etching solution using a stalagmometer is based on the relationship between the weight of a drop of the solution (which creates a shear force on the solution) and the surface tension of the surface of the solution drop (which keeps the liquid together).

For a given volume of liquid, the surface tension, as measured with a stalagmometer, is proportional to the density of the solution and inversely proportional to the number of drops.

Note:  prior to commencing any of the following steps, ensure that you have carefully reviewed, understood and implemented all of the safety information noted in section 10 of this document.