🟡 BRASS
Brass Casting: Cast Yellow Brasses, Zinc Loss, and the C360 Question
Brass casts more easily than almost any copper-base material, which is why valve bodies, fittings, and decorative hardware have been cast in brass for centuries. The wrinkle for buyers is that the brass grades they know, C360 free-machining brass, C260 cartridge brass, and naval brass, are wrought alloys, and the foundry pours cast yellow and red brasses (the C8xx series) instead. Understanding that swap, plus the perennial issues of zinc fuming and dezincification, is what separates a clean brass casting buy from a problem one.
ISO 9001ISO 14001ISO 13485
Wrought C360 and C260 versus the cast C8xx brasses you actually get
C360 (free-machining brass, 61.5Cu-35.5Zn-3Pb) and C260 (cartridge brass, 70Cu-30Zn) are wrought alloys optimized for machining bar and deep-draw sheet respectively. Foundries do not pour them. The cast analogs live in the C8xx 'cast copper alloy' series: cast yellow brasses like C85700 and C85800 (high-zinc, good fluidity, the closest to a cast 'yellow brass' for hardware and fittings), and the cast red brasses like C83600 (85-5-5-5, the classic 'ounce metal' or 'red brass' for valves and plumbing) which despite the name are really leaded tin bronzes used where pressure-tightness and machinability matter.
The practical mapping: if a print calls out C360 for a machined fitting, a cast version uses a leaded cast brass like C85800 (high-fluidity die-cast brass) or a leaded red brass C83600 for pressure parts, both chosen so the casting can be machined and stays pressure-tight. For C260's deep-draw, corrosion-resistant role, there is no real casting equivalent, that alloy exists to be drawn, not cast, so cast parts use a different yellow or red brass selected for the service.
Naval brass (C464, 60Cu-39Zn-1Sn) is a wrought alloy for marine hardware; its tin addition fights dezincification. The cast counterpart for marine duty is typically a manganese bronze (high-strength yellow brass, C86x00) or an inhibited cast brass. The buyer action is the same as for other metals: specify the cast C8xx grade and the governing standard (ASTM B584 for sand-cast copper alloys), not the wrought number, and state whether pressure-tightness, machinability, or dezincification resistance is the priority.
Zinc volatility, dezincification, and lead-free plumbing rules
Brass is copper plus zinc, and zinc boils at 907 C, below the temperature of molten brass. That means zinc fumes off during melting and pouring, shifting the alloy composition toward higher copper and creating white zinc-oxide fume that foundries must capture for worker safety and environmental compliance. Good practice keeps pour temperatures controlled and accounts for zinc loss in the charge, but it is a real process variable, especially in the high-zinc yellow brasses.
Dezincification is the corrosion failure that haunts brass in service: in aggressive water (soft, acidic, or chloride-rich), the zinc selectively leaches out of the alloy, leaving a porous, spongy copper skeleton with no strength. High-zinc yellow brasses (over about 15 percent zinc) are most vulnerable. The fixes are an inhibitor addition (arsenic, antimony, or tin, giving 'DZR' dezincification-resistant brass), choosing a lower-zinc red brass, or specifying a dezincification-resistant cast alloy for potable water and marine use. For any brass casting that will see water service, ask the foundry specifically about dezincification resistance.
Lead is the other regulatory flashpoint. Traditional cast brasses and red brasses contain 2 to 7 percent lead for machinability and pressure-tightness, but potable-water hardware in the US (Safe Drinking Water Act, NSF/ANSI 61 and 372) now limits lead to 0.25 percent weighted average. That has driven a whole family of lead-free cast brasses and bronzes (bismuth or silicon substituting for lead). If your brass casting touches drinking water, you must specify a certified low-lead alloy, this is non-negotiable and a frequent source of compliance failures when buyers carry over an old leaded grade.
Process routes and finishing: from sand valves to die-cast hardware
Brass castings split by volume and detail across three main routes. Sand casting (green sand or no-bake) is the default for valve bodies, large fittings, and low-to-moderate volumes; it holds tolerances around plus or minus 0.03 in with 250 to 500 microinch finish and is the standard for ASTM B584 red and yellow brass plumbing and valve work. Permanent mold (gravity die) improves finish and tolerance and refines grain for higher volumes of mid-size parts.
High-pressure die casting in brass is real but specialized, the high-zinc die-cast brass C85800 (and the European CuZn die-cast alloys) are formulated to flow well and not solder to the steel die, used for plumbing fittings, locks, and decorative hardware at high volume with excellent finish (32 to 63 microinch) and thin walls. The trade-off is shorter die life than aluminum die casting because brass pours hotter and is harder on tooling.
Finishing is often the point of a brass casting. Brass takes polishing, plating (chrome, nickel), and decorative finishes beautifully, which is why architectural hardware, faucets, and trim are cast brass. Machinability is excellent in the leaded grades (free-machining cast brass rates near 90 percent), so cast brass parts thread, drill, and turn easily for valve seats and ports. Budget for the finishing, plating and polishing can exceed the casting cost on decorative parts, and confirm the lead and dezincification specs early, because retrofitting a compliant alloy after tooling is costly.
Frequently Asked Questions
Not directly, C360 is a wrought extrusion and bar alloy, not a casting alloy, so foundries pour a cast brass with similar character instead. The usual substitutions are the leaded cast brasses and red brasses: C85800 (a high-fluidity leaded yellow brass used for die casting and permanent mold) or C83600 (the classic 85-5-5-5 leaded red brass, really a leaded tin bronze) for sand-cast pressure parts. These cast grades retain the excellent machinability that makes C360 attractive, free-machining cast brass rates around 80 to 90 percent machinability, so the cast part threads, drills, and turns easily for valve seats, ports, and fittings. The cast grades are also formulated for pressure-tightness and good mold fluidity, which wrought C360 is not. If your print calls out C360 for a cast part, specify the cast C8xx equivalent under ASTM B584 (or B30 for ingot) and state whether machinability, pressure-tightness, or appearance is the priority. And critically, if the part touches potable water, you must move to a certified low-lead alloy regardless of the original grade, since traditional leaded brasses exceed the 0.25 percent lead limit.
Dezincification is a corrosion process where zinc is selectively leached out of brass in aggressive water, soft, acidic, chloride-bearing, or stagnant, leaving behind a weak, porous copper skeleton that looks like brass but has lost most of its strength and can fail under pressure. It is most severe in high-zinc yellow brasses (above about 15 percent zinc) and is a real failure mode in plumbing, marine, and water-handling castings. Prevention has three routes. First, use a dezincification-resistant (DZR or CR) alloy that includes a small inhibitor addition, arsenic, antimony, or phosphorus, which stabilizes the zinc against selective leaching. Second, choose a lower-zinc alloy: the red brasses and tin bronzes with under 15 percent zinc are inherently far more resistant, which is why C83600 red brass is standard for water valves. Third, add tin (as in naval brass and its cast counterparts) for marine service. For any brass casting destined for potable water, cooling water, or seawater, specify dezincification resistance explicitly and ask the foundry for the inhibited or low-zinc grade; do not assume a generic yellow brass will survive, because in soft or acidic water it can dezincify within a few years.
Not for surfaces that contact potable water. US law (the Reduction of Lead in Drinking Water Act amending the Safe Drinking Water Act, plus NSF/ANSI 61 and NSF/ANSI 372) limits the weighted-average lead content of wetted surfaces to 0.25 percent. Traditional cast brasses and red brasses like C83600 contain 4 to 6 percent lead for machinability and pressure-tightness, far above that limit, so they can no longer be used for faucets, valves, fittings, and other drinking-water hardware in the US (and similar rules apply in Canada and the EU). The industry responded with low-lead and lead-free cast copper alloys that substitute bismuth or silicon for lead while keeping castability and machinability, such as the bismuth red brasses (C89833, C89844) and silicon brasses/bronzes. These are certified to NSF 61/372. For non-potable applications, industrial valves, hydraulic fittings, decorative hardware, machine components, leaded cast brass is still perfectly legal and widely used because the lead aids machining and pressure-tightness. The buyer's job is to confirm whether the part contacts drinking water; if it does, you must specify a certified low-lead alloy, and carrying over an old leaded grade is a common and costly compliance failure.
Brass is a mid-cost casting metal. Copper and zinc drive the alloy price; as a planning figure finished sand-cast brass and red brass run roughly $5 to $12 per pound in moderate volume, with low-lead and high-strength manganese bronzes at the higher end. A small cast valve body might be $15 to $60 each; decorative hardware can be much less at die-cast volumes. Tooling is a sand pattern at $2,000 to $12,000, a permanent mold at $8,000 to $30,000, or a die-cast die at $20,000 to $80,000. Lead times to first articles run 4 to 8 weeks for sand and permanent mold, longer for die-cast tooling. Production lead after tooling proof is 2 to 4 weeks. The cost drivers worth watching: whether the part needs a certified low-lead alloy (which costs more than traditional leaded brass), dezincification-resistant chemistry, pressure testing for valves, and finishing, polishing and plating on decorative parts can equal or exceed the casting cost. Brass machines easily and takes finishes well, so secondary machining is usually cheap, but get a quote that separates raw casting, machining, testing, and any plating so you can see where the money goes.
Choose by volume, size, and detail. Sand casting is the default for valve bodies, large fittings, pump parts, and low-to-moderate volumes (a few to a few thousand pieces); tooling is cheap at $2,000 to $12,000, there is essentially no size limit, and it suits the ASTM B584 red and yellow brasses used in plumbing and valves. Tolerances run plus or minus 0.03 in with 250 to 500 microinch finish, so plan machining stock on critical surfaces. Permanent mold (gravity die) raises tooling cost but improves finish (150 to 250 microinch), tightens tolerances, and refines grain for higher mechanical properties, good for thousands of mid-size parts. High-pressure die casting suits high-volume small-to-medium hardware, plumbing fittings, locks, decorative trim, using high-fluidity die-cast brass like C85800; it gives excellent finish (32 to 63 microinch), thin walls, and the lowest per-part cost at scale, but tooling is $20,000 to $80,000 and brass die life is shorter than aluminum because brass runs hot and is harder on the steel dies. The rule of thumb: low volume or large parts go sand, mid volume goes permanent mold, high volume of small hardware goes die cast.
Last updated: July 2026
Find Brass Casting Suppliers
Search verified shops that handle Brass casting.
No logins. No email gates. Just results.