For more than 70 years PFOS-containing wetting agents have been used as constant preventer for wetting agents and spray mist in chromium-plating processes.
Until now they were primarily used for wetting surfaces to be coated or chemically transformed. Adhering gas bubbles that develop/form during chromium-plating processes in hexavalent chromium media are reduced by lowering the surface tension. Thus, coating errors can be prevented.
But over the past few years, disadvantages of POFS-containing wetting agents were pointed out more and more frequently. They include:
- Strong foam generation and contamination of the plant and extraction system
- Increased danger of hydrogen deflagration
- Poor solubility, especially in older electrolytes
- Pore formation in chrome layers when overdosed
As a result, PFOS-free alternatives became more and more established and electroplating baths are continuously adjusted to PFOS-free solutions.
Advantages of those foam-free wetting agents are not only the reduced carry-over and hydrogen deflagration as well as the very good solubility but also the simple concentration measurement and the management of emission by measuring the surface tension. PFOS-free solutions are cost-effective as well environmentally-friendly.
With foam-free wetting agents dosing according to visual judgement is no longer applicable. While in the past the foam layer was used to determine the wetting agent concentration, today analysis methods are used to determine the surface tension.
Within a study to evaluate the effectiveness of the new foam-free wetting agent generation, one of the leading global chemical suppliers, Enthone GmbH, highly recommends the SITA DynoTester+ to determine the surface tension.