BS EN ISO 4623-2:2016

What is ISO 4623-2 - Filiform corrosion paint standard about?  

Filiform corrosion is a particular form of corrosion that occurs under thin coatings in randomly distributed threads like filaments. Filiform corrosion is also known as under film corrosion, filamentary corrosion, or worm track corrosion.  

ISO 4623-2  describes a test procedure for assessing the protective action of coatings of paints or varnishes on aluminium against filiform corrosion arising from a scribe mark cut through the coating. ISO 4623-2 is only suitable for assessing the performance of the coating/substrate combination tested.  

Note: ISO 4623-2 is not suitable for predicting the performance of the coating on different substrates. 

Who is ISO 4623-2 - Filiform corrosion paint standard for? 

ISO 4623-2  on filiform corrosion paint standard is useful for: 

• Manufacturers of paints and varnishes 
• Product development teams 
• Quality control teams 

Why should you use ISO 4623-2 - Filiform corrosion paint standard?  

A scribe mark cut through a coating of paints or varnishes on metal can give rise to various types of corrosion, such as blistering of the coating, corrosion of the metal under the coating as well as filiform corrosion. Filiform corrosion tends to develop under specific conditions of temperature and relative humidity and when traces of acids, bases, or salts are present either under the paint coating or at breaks in the coating. These conditions are often found in marine and/or industrial environments. A certain amount of under-corrosion of the coating, starting from the scribe mark, will always occur. Filiform corrosion, however, is considered to be present only if the typical pattern in the form of threads is obvious. 

ISO 4623-2 provides you with guidelines on test panels in terms of materials and dimensions, preparation and coating, drying and conditioning as well as thickness of coating. In addition ISO 4623-2 also gives you details on evaluation of the degree of filiform corrosion and precision. Using ISO 4623-2 guidelines, you can determine the protective action of coatings of paints or varnishes on aluminium against filiform corrosion arising from a scribe mark cut through the coating. ISO 4623-2 guidelines enable you to provide your customers with suitable, reliable, and high-quality coatings. 

What’s changed since the last update?  

BS EN ISO 4623-2:2016 supersedes BS EN ISO 4623-2:2004. BS EN ISO 4623-2:2016 includes some technical changes with respect to BS EN ISO 4623-2:2004. These include: 

• Duplicate determination has been changed to triplicate determination 
• Information on the shape of the scribe marks has been added 
• The width of the scribe marks has been changed to be in line with EN 3665 
• A note on using the CASS test for initiating filiform corrosion was added 
• The supplementary test conditions previously in Annex A have been integrated in the test report