Pickle not removing the stubborn brown scale on gold

[Hello from Austria]

Hello and Guten Abend! I've melted some 9ct gold into shape which worked fine, but then the brown, furry scale is not being removed by the pickle. Increasing the heat of the pickle hasn't worked, nor leaving it in for a long time. As the melted surface is quite natural and uneven I don't want to start taking it off manually, because it would take away the nice texture, and I need to understand what's happening here anyway. Could you wise elders kindly please explain what's going on here? Danke schon!

[silken]

Guten Abend! ;) I really wish I could speak more German.

9ct gold has an awful lot of copper (generally along with silver and zinc) in the alloy so it is prone to that horrible stubborn scale that you speak of. My solution to this is to use yellow (coarse) radial discs on about 15,000RPM. This removes the scale very effectively without taking away the bumpy, uneven texture. It leaves the metal with a matte finish but retains the underlying lumps and bumps. The good thing about radial discs is their versatility and ability to reach areas that traditional tools and polishing compounds sometimes cannot. The yellow ones are great for removing any sort of fire scale left after pickling and you can progress up through the different colours to get a near mirror finish if desired. If you want to keep the matte/satin finish, I generally just use the yellow radials, maybe followed by the blue if I feel like it and I quite often use a fine or medium frosting wheel to give a longer lasting matte finish.

What type of pickle are you using? Sometimes changing to a different type of acid/pickle makes a big difference. A lot of people swear by alum instead of the traditional, highly corrosive acids.

Ich hoffe das hat dir geholfen (one of the only things I remember from my German lessons, I hope I have said that correctly)!

[Dennis]

Emily has explained it all, but I think if you are using safety pickle, then warming it until it steams gently will help. To finish I would only use a jewellers' brass brush and liquid soap which I'm sure will give you the result you are looking for.

Gute nacht. Schlafen sie wohl. Dennis.

[Hello from Austria]

Hello Emily and Dennis! Thank you very much for your detailed answers, this gives me plenty to work with. I'll experiment with your suggestions. Thanks again and till next time - bye!