This Technical Corrigendum 1 to International Standard 13500:2008 and API Specification 13A, Specifications for Drilling Fluid Materials, includes a newly available drilling fluid product. This corrigendum covers the physical properties and testing of Barite 4.10. This corrigendum is prepared as an alternative to ISO 13500, Clause 7, Barite/API Spec 13A, Section 7 and should not be interpreted as a replacement for Clause or Section 7 Barite. This International Standard is intended for the use of manufacturers of named products.