I want to try casting bronze at some point, but where I live 99.9% pure tin costs almost 1 DKK a gram, meaning 100 g costs 15.22 USD. That is very expensive, so can I use scrap tin and pewter instead? I know that soldering tin is filled with other stuff, so that's not usable either.
Get to onyxmet. I have good experience and already have ordered tin. Now they charge $7.50 per 100 grams in pellets. https://onyxmet.com/index.php?route=product/category&path=69_114_173
Are you sure about that? Lead free solder is 95% tin and 5% antimony, although antimony isn't commonly used in bronzes today it was sometimes used in ancient and medieval bronzes.
I've been accumulating 8Kg of tin so far and had a chance to get it tested on a hand held X-ray Fluoroscope: the antimony would dilute to below acceptable limits for bronzes although it can weaken bronze used for engineering purposes if too high, the rest are all good bronze ingredients including the bismuth which replaces lead in modern plumbing bronzes.
i Just bought tin off of Ebay, $24.99/ Lb Rotometals is just under $30/Lb Belmont is at $36/Lb I have to buy tin to line the mugs, so I feel your pain, financially you are better off to just buy good bronze scrap if that is an option V/r HT1
I see I was wrong there. Thanks rocco and Mark's castings. So I can't use scrap pewter and tin for some small sculptures where they don't have to be perfect? If not, I'll definitly look to Onyxmet.
That XRF readout is what my scrap pewter is made of, if I used it for making tin bronze it would be perfectly fine as the antimony would be diluted below the upper acceptable limits and everything else is an ingredient. I find the 0.84% lead content interesting considering it was all melted from pewter mugs but then I hear antique pewter did contain some lead. This specification for tin bronze lists 0.2% antimony maximum, so with 9% of my pewter that 2.1% antimony becomes 0.19% of the total bronze....right on the limits for a commercial product and should be fine for home foundry players. https://www.morganbronze.com/wp-content/uploads/c903_tin_bronze.pdf
This is great, thank you very much! My scrap metal comes from old decorative items like plates and vases: Do you think they have the same composition as your scrap items? Extra question: I've noticed that there are very dark tin items (plate bottom right), and shiny tin items (tankard in the middle), what's the difference? Guess I'll finally use that box of rat poison my great-great-grandfather left for me.
It's hard to say, most of my pewter is from the Pacific rim in origin so it's supposed to be pure tin. Older pewter can have antimony and really old pewter can have lead or silver content. I'd heard that antique pewter with lead develops a black patina but then so should silver when you think about it. The main takeaway here is that you'll have around 95% tin and whatever alloying elements would increase hardness and prevent problems with pure tin, like cold weather "tin pest".
