Study of a brass lamp
The client asked our laboratory for help in solving the problem of the occurrence of dark spots on the surface of the brass lamp elements. To find the cause of this problem, we did a series of tests.
1. Macroscopic tests
On the basis of macroscopic observations, we found that the discoloration is point-like and as a cluster of spots. These areas were subjected to detailed microscopic examination and microanalysis of EDS / EDX chemical composition.
2. Microscopic tests
We have shown that point-like stains are caused by the presence of metal chips trapped in the varnish covering the lamp components. The stains in the clusters are the products of brown brass corrosion. In the microstructure of the material, we observed non-metallic inclusions, which constitute a material defect and should not be present.
3. EDS / EDX microanalysis of the chemical composition
The observed non-metallic inclusions and corrosion products were analyzed in terms of their chemical composition. Research has confirmed their nature.
The cause of the stains are impurities trapped in the varnish, e.g. chips of other metals, and material corrosion – corrosion products with a brown color. Why does the material corrode? Non-metallic inclusions in brass during washing and degreasing the surface of the lamp before varnishing, reacted with chemical reagents, the products of these chemical reactions are dark brown in color.
What solution did we provide to the client? If it is possible to change the material supplier, if it is not possible to change the washing and degreasing reagents so that non-metallic inclusions do not react with them chemically. All test results as well as conclusions and recommended solutions to the problem have been described in detail in the test report provided to the client.