For many decades, chromate conversion coating containing chromium(VI) was considered the standard method for corrosion protection and as a primer for subsequent coatings. Due to regulatory requirements and increasing environmental and occupational safety standards, chromium(VI)-free systems are now required.

Slotopas AL 4270 was developed by Dr.-Ing. Max Schlötter GmbH & Co. KG in response to these requirements. The process relies on passivation with a reduced chromium content based on chromium(III) and zirconium. It thus combines a high level of protection with modern process robustness and closes the gap that purely chromium-free systems have so far been able to fill only to a limited extent in terms of performance.

In neutral salt spray tests lasting 336 hours, no signs of corrosion were observed on aluminum sheets made of the AW-5005 alloy, which underscores the reliable protective effect of the process.

This means that all content on the page has been consistently updated to use Slotopa's AL 4270 and the correct chromium(III)-zirconium base. Would you also like the expandable text for the two „Learn More“ buttons or a meta description for the page?

Passivation with Slotopas AL 4270 offers several advantages for demanding manufacturing processes:

Chromium(VI)-free solution based on chromium(III) and zirconium, which complies with current environmental standards and regulatory requirements such as REACH.

Reliable Corrosion Protection through a transparent, defect-free conversion coating that also serves as a bare corrosion-resistant layer without the need for an additional organic coating.

Excellent bonding base for paint finishes and adhesive applications, as confirmed by established test methods such as the multi-impact test, cross-cut test, and stamp tear test in accordance with the relevant DIN standards.

Process Reliability and Cost-Effectiveness thanks to stable bath control with a constant pH, a wide temperature range of 15 to 40 degrees Celsius, and continuous filtration to maintain bath stability.

The result is a stable, cost-effective, and reliable solution that is well-suited for automated processes and high-volume production.

Slotopas AL 4270 was developed specifically for the passivation of aluminum surfaces. The process forms a transparent, uniform conversion coating on aluminum and aluminum alloys.

It should be noted that the alloy composition and preceding pretreatment steps can influence the formation of the conversion layer. The process parameters are therefore tailored to the specific material in order to achieve reliable and reproducible results.