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Why are my brass castings changing colour once tumbled?


#1

Hi, I’m casting pieces of lace applique in yellow brass and love the rich warm yellow colour of the castings when they’re freshly casted. However, the colour changes to a lighter, not-so-rich tone when I tumble them with steel shot. I am only guessing that it is the tumbling process which affects the colour. Any suggestions of how I should approach finishing the cast lace pieces and retaining the colour? I seal the cast pieces with a clear lacquer to prevent/delay tarnishing but have been advised to have them gold plated. Any thoughts and advice will be appreciated.
Warm wishes from South Africa where summer is finally here!
Desiree


#2

Desiree- With brass or bronze, I’d use rock (ceramic) for your first round of tumbling, and oak for your finish round of tumbling. NOT steel shot. I don’t know the chemistry of the steel shot with bronze and brass, but I find it more effective to use oak.


#3

Thank you so much for the advice. I was wondering if the steel shot was the reason for the change in metal colour. Are you saying I should tumble with wood oak? I haven’t seen wooden pellets in my jewellery supply shop in Cape Town. I’ll have to search online for a company which will shop to South Africa.