The new Zundex product range is used to treat metal surfaces after heat exposure, such as welding. In total, the range consists of three products that can be used ready-to-use for copper, copper alloys, nickel, iron and steel as well as for stainless and acid-resistant stainless steels of all kinds.

In many work processes that require heat treatment, changes to the material surface inevitably occur. These are mainly oxidation phenomena that lead to an undesired discolouration of the metal. Welders, for example, are familiar with the problem of tarnish, which can hardly be avoided. With our Zundex products, these oxides can be removed quickly and easily,” explains Markus Geßner, Marketing and Sales Manager at Emil Otto GmbH. The same applies to surface discolourations that occur when using saw blades and similar, high-speed machining tools. “Whenever the metal is exposed to high temperatures, these changes can occur. That is why they are also known as burn marks. The Zundex pickling products provide a quick remedy by chemical means. Their active ingredients react intensively with all metal oxides. This dissolves the oxides and they can be easily removed afterwards,” Geßner continues.

The new pickling products are free of hydrochloric, sulphuric and nitric acid. They do not contain hydrofluoric acid or any hydrofluoric acid salts. Special wetting agent additives cause a fast and uniform reaction on the surfaces to be treated. “When using our Zundex products, a somewhat slower reaction is sometimes observed in comparison to pickling mixtures of more aggressive and therefore often highly toxic mineral acids“, Geßner knows to report. However, this apparent disadvantage is offset by the advantages of the milder Emil Otto pickling agents, which do not emit free chlorine or nitrous gases.

If the surfaces to be treated are not only discoloured by oxidation, but also have other impurities such as burnt oil or resin residues, coarse welding slag or other heavy dirt, these must first be removed mechanically. Then apply the Zundex preparation by means of a brush or similar. For the treatment of already mounted, sloping, vertical or overhead surfaces, Emil Otto also offers a ZUNDEX paste suitable for this purpose. As soon as the oxide layers have been chemically transformed and are removable, they can be removed by brushing or wiping. In case of particularly heavy contamination, the treatment with Zundex can be repeated.

About Emil Otto

Since 1901 “Emil Otto” stands for top quality. As owner-managed company, Emil Otto is committed to the development and manufacturing of high-quality fluxing agents. In particular the fluxing agents for electronics production, strip tinning, cooler construction as well as for galvanizing are used by market leaders at home and abroad.

Over the years, reliable products and a high level of customer care have become the signature. The manufacturing takes place in accordance with the latest standards, the quality- and environmental management system has been certified for many years. Emil Otto responds with high flexibility to customer requests. Special products or product adaptations are developed and implemented in collaboration with system manufacturers and institutes. More information: