John O. Kopf wrote:

Ned Simmons wrote:

SNIP

One of the most widely used alloys for underwater marine
hardware is 85-5-5-5 (Copper-Tin-Lead-Zinc), usually
pronounced 85-three-5. The ASM Metals Handbook refers to
85-5-5-5 as a bronze. SNIP


I've also seen the same alloy called "Gunmetal" (from British catalogs)

supposed to be easy machining (often appears in steam engine kits)

JK

You're right. Sounds like leaded gunmetal. Easy to cast and machine.
There is something about the addition of tin that prevents the zinc from
leaching.

I am beginning to see that the line between brass and bronze is so fuzzy
that the only real difference seems to be the name. Red brass can be
94% copper and 6% zinc while phosphor bronze can be 11% zinc.

Fortunately I do know that about half of my bronze collection is Everdur
silicon bronze with almost no zinc. It is government surplus with the
alloy number CA655/MIL-T6013A cast into it. The miscellaneous pieces
were what I was worried about. It is mostly regular commercial pump
castings.

OTOH, if a pinch of lead, a smidgen of tin and a dab of zinc will
improve the casting quality maybe a lump or two of the less well
identified scrap will help. :-)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com