Guides / Compliance

Leaded and Lead-Free Brass Compared, and the Standards That Decide It

September 21, 2026

There are two reasons to pick a brass alloy. One is what the part has to do. The other is what the law says about where the part ends up. On brass, the second one usually decides first.

What the lead is doing in there

Free-cutting brass C360 is roughly 61.5 percent copper, 35.5 percent zinc and 3 percent lead. The lead does not dissolve into the alloy. It sits in it as soft particles that break the chip and lubricate the cutting edge.

That is why C360 is rated 100 for machinability and why every other metal is measured against it. It is also why removing the lead is not a small change.

When lead-free is not optional

In the United States, the Safe Drinking Water Act and NSF/ANSI 372 limit the wetted surfaces of any pipe, fitting or fixture in a potable water system to a weighted average of 0.25 percent lead. NSF/ANSI 61 covers what may leach out of the material more broadly. California moved first with AB 1953, and the federal limit followed.

At around 3 percent lead, C360 is an order of magnitude over that line. It does not matter how well it machines. If your part is one component in a larger assembly, the weighted average lead calculator works out where the assembly lands.

Other markets apply their own rules. The EU restricts lead in electrical and electronic equipment through RoHS and in vehicles through the ELV directive, both with exemptions for copper alloys that have been narrowing over time, and drinking water materials are approved nationally rather than through one EU-wide list. The safe working assumption for an export part is that the limit is coming, not that it is absent.

Food contact and medical fluid contact parts usually land in the same place, through a different route.

The two lead-free routes

Silicon brass, the C69300 family

Silicon replaces lead as the alloying trick. Machinability lands near 80 against C360 at 100, which is still excellent. The alloy is roughly twice as strong as C360 and highly resistant to dezincification, so it holds up in hot water where ordinary yellow brass does not.

The cost is on the shop floor. Silicon brass work hardens, so it wants sharp tooling, a positive rake and a feed that keeps cutting rather than rubbing. Threads in particular behave differently. A shop that has run it will quote it without a guess margin. A shop that has not will either refuse or pad the price.

Bismuth brass, the C49300 and C49350 family

Bismuth behaves much like lead as a chip breaker without the toxicity, so these alloys are the closest thing to a drop-in replacement for C360. An existing program often runs with adjusted feeds rather than a redesign.

The trade is availability and price. Bismuth is expensive and the bar stock is not held as widely as C360, so lead times on an unusual diameter can be long.

What it costs you

	C360 leaded	C69300 silicon	Bismuth brass
Lead, nominal %	2.5 to 3.7	under 0.09	under 0.25
Machinability	100	80	80
Relative bar price	baseline	higher	higher
Behaves like C360	yes	no	close
Dezincification resistance	poor	high	moderate

Published typical values for the alloy. They describe the material, not a promise from any shop.

Two rules of thumb hold up in practice. Expect a longer cycle rather than a different process, and expect the bar price rather than the machine time to be the bigger part of the increase.

How to write it on the drawing

Write the standard, not only the alloy.

“C69300” tells a shop one thing it can buy. “Wetted part, must comply with NSF/ANSI 61 and 372, material certificate 3.1 required” tells the shop what has to be true and leaves it free to offer whichever compliant bar it can actually source that week. On a part that repeats, that freedom is worth money.

Then say whether you need the certificate with every shipment or only with the first article. Shops price those two very differently.

Where to go next

The wider cost picture is in brass CNC machining, why it is cheap and where the cost hides. If you are choosing between grades for a reason other than lead, see the brass alloys and what each one is for.

Frequently asked questions

Keep reading

• RoHS Exemption 6(c) and What Happens to Leaded Brass in 2027
• NSF/ANSI 61 and 372: What They Mean for a Brass Part