All metals aren't created equal each have their own limitations when it comes to chroma or saturation level. This means that the intensity or vividness of the color achieved with a particular metal powder may have a maximum limit.
Regarding the exothermic reaction, it seems that the metal powder increases the release of heat during the reaction. As a result, it is important to take precautions when storing the product containing the metal powder. If the bottle is stored outside of its packaging, it should not be exposed to temperatures exceeding 28°C. However, if the bottle is wrapped in insulation as part of the package, it can help mitigate the effects of external temperature and provide some protection for the product.