Making tombak - golden color brass alloy. Wire drawing.

I am preparing for a new project, I want to make a replica of the spear from Norway. In the original archaeological find silver, copper, and copper alloy – brass have been used. I was able to buy pure silver and copper but not low zinc brass alloy, so I decided to make it myself. The copper alloy with low zinc content is called tombac (5% to 20% of zinc). The color of tombac is gold-yellow and imitates gold. It is also very good for cold forming, what is important in terms of metal inlay, it is softer than CuZn37 brass. To make tombac I used CuZn37 brass and pure copper. CuZn37 alloy has 63% of copper and 37% of zinc. To make tombac with 15% percent of zinc I have to decrease the amount of zinc in the alloy for this I have to add some extra copper. photos of the spear: