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View Full Version : Which Flux Powder?



Lindyloo
08-09-2009, 09:50 PM
Which is the right flux powder to use for melting scrap silver for casting?

ps_bond
08-09-2009, 09:56 PM
Whatever works.

I tend to use borax & charcoal; I'd try ammonium chloride if I had any on hand.

Lindyloo
08-09-2009, 09:59 PM
You must have a chemical cupboard stuffed full Peter. I do have borax powder - the kind you use for cleaning. Is that the same as you get with a borax dish? But I don't have ammonium chloride - where do you get that? Lots of sodium chloride, though.

Perhaps I'll have to buy a dedicated one - was looking at easy flo flux powder and tenacity, but the first had a low temp limit, and the latter said it had to be mixed with water. So I'm confused.

ps_bond
08-09-2009, 10:20 PM
I have a bit of an assortment... I usually buy powdered borax from the local Chinese grocers (along with bicarb by the 3kg bag) - and borax is borax (sodium tetraborate decahydrate).

Easyflow & Tenacity fluxes I have around too; I only use them with Easyflow & Silverflow solders though.

Rose Chemicals might have ammonium chloride?

Lindyloo
08-09-2009, 10:29 PM
How do you mean clean?

Ominicci
09-09-2009, 10:37 AM
On the Cooksons Knowledgebase it says you can just use Borax paste from the borax cone. I have only got one of the tiny scorifiers so is that OK or do you REALLY need borax powder?

ps_bond
09-09-2009, 11:22 AM
The only difference between the borax I buy as powder and the borax in a cone is the cone is stuck together; they're both decahydrate (10 molecules of water to 1 of sodium borate). There will be a bit more water in the paste than there is in the powder, and that's it. But the water will be driven off at the temperatures you're aiming for!

Ominicci
09-09-2009, 11:43 AM
Cheers both! :Y: