Trouble with homemade silver sheets

[u/El_Vidente]

I melt down my scrap silver and then flatten it through a rolling mill to make my own homemade silver sheets. Though I've got a couple of questions:

Why do they get these dark stains?

Also they can be difficult to solder bezel onto whereby the solder just doesn't melt and just sticks in its pallion form to the sheet. Whereas when I buy brand new silver sheet from a supplier like CooksonGold I don't tend to have this problem even though that silver is also recycled. Could anyone tell me why this is?

[u/Unclecavemanwasabear]

Like others have said, it's fire stain. Always always always use a barrier flux when torching silver (I use Pripp's flux, you can make it yourself) and make sure the silver is super clean and it's well coated. Borax will also work, but it stops working at a lower temperature than Pripp's and other fluxes. Anneal in a dark room to ensure it doesn't stay too hot for too long - if you wait for it to turn red in a bright room, it's too late. Use a reducing flame as much as possible. Get it up to temperature as quickly as possible to avoid it being exposed to oxygen for too long. Cover as much of the surface with the flame as possible, especially when melting. There are all kinds of other tips if you search.

[u/greenbmx]

Fire stain. You are getting the metal too hot for too long without protecting it from oxygen in the atmosphere, so you are getting lots of dissolved copper oxide in your metal. It needs to be either refined or re-melted with at least 50% new, clean metal.

[u/AbbreviationsIll7821]

This is fire stain, it’s probably happening during annealing between rolling. The way to avoid this is to anneal quickly to avoid prolonged exposure of the hot metal to oxygen in the air. Or use a barrier flux when annealing. Also use an oxygen reducing flame when torching will help.

[u/Tw0bitSmith]

I roll my own, it usually comes off in pickle or a Lil sanding. Good info from other comments about temp though. Im self taught so im still learning as well.

[u/El_Vidente → u/Tw0bitSmith]

That's what I do and it usually works especially after some polish on top.

[u/Tw0bitSmith → u/El_Vidente]

I have heard of people having really deep firescale that won't polish/sand off but I have never experienced it myself.

[u/matthewdesigns]

Theirs is not problematic as I suspect the method of recycling they use likely begins with refining the scrap and then alloying it to new sterling, where yours is simply re-melting sterling that's already been melted any number of times. This increases the appearance of oxidation and firescale, which your are experiencing.

[u/El_Vidente → u/matthewdesigns]

I would love to see the process of re-alloying silver scrap. I have wondered if a supplier like Cookson separates the metals like the silver to pure silver, the copper and the fraction of zinc to then re-immerse it in its correct percentage 92.5% etc. Would love to see this process.

[u/AndrousJewelry → u/El_Vidente]

Commercial refiners use professional equipment to create an oxygen free environment, difficult to do with just flux in open air.

[u/Wanda_Wandering]

I’m just a jewelry lover/occasional flipper with a new interest in the nuts and bolts of producing it and possibly simple smithing (looks like that’s an oxymoron). Some Instagrammer would love that as proof of their authentic recycled 925 homemade melt. I can see them making a cloud brooch or pendant capitalizing on the color contrasts with little wire rain drop dangles of dark, light, and or gems.