According to Nice classification heading for class 40 states Treatment of materials is include in Class 40. The heading gives you a brief broad overview about what exactly is including in a particular class.
This Class includes, in particular: – services relating to transformation of an object or substance and any process involving a change in its essential properties (for example, dyeing a garment); consequently, a maintenance service, although usually in Class 37, is included in Class 40 if it entails such a change (for example, the chroming of motor vehicle bumpers); – services of material treatment which may be present during the production of any substance or object other than a building; for example, services which involve cutting, shaping, polishing by abrasion or metal coating. This Class does not include, in particular: – repair services (Cl. 37).