I'm no metallurgist, but...

[ubervamp]

Hi all
Not quite sure where to post this, so I'll try here, and hopefully the Mod's can move it if there's somewhere more appropriate!

I've gathered a few notes and questions I haven't been able to find an answer to, so hopefully someone here can answer some of them?

1) I understand that "yellow brass" for cap badges was fazed out in the 1890's in favour of "Gilding Metal", and that the main difference lies in the brass/zink ratio, with gilding metal having a higher percentage of brass? Is this correct?

2) The term "gilding metal" refers to the fact that this ratio was better suited to the process of gilding the badge, and also leads to the brass used usually having a redder hue?

3) If these assumptions are true, would that mean that "yellow brass" badges prior to the 1890's was not gilded?

4) I have somewhere a positively yellow post-1917 Army Labour Corps badge. Is that then simply due to normal colour variation in the g/m mixture? It is highly polished, and seems to be coated/sealed with a thin film (wax). This would prevent oxidation (patina) accumulation, I suppose, and explain why it's retained it's bright colour?

5) Were 1916 all g/m's ever gilded? Or would that have been omitted to save time?

6) In the pics I have two Army Medical Corps badges. One is "normally" oxidated, but retains some gild residue in the lower parts of the leaves.
The other (probably newer, since I think this pattern lasted up through WW2?) looks pristine, never worn probably, and never polished, and retains all it's gilding. Does that mean that gilding prevents/slows down the oxidation process, since the brass is not exposed?

Quite a few questions, but I thought it might be best to gather them in a single posting!

As always, any answers or input much appreciated!!

Thanks in advance

Colin