From the top: Glass faucet designed by Phillipe Starck for wood and brass faucet from Omax Rubinetteria of Italy, and the brass and ceramic Vas faucet (now discontinued). As far as we know the Starck faucet has never actually be manufactured.
Faucets can also be made of plastic.
The traditional material for faucets is brass.
Brass is prized for faucets because
Brass is an alloy of copper and zinc. There are over sixty compositions of brass. Copper content ranges from 58% to 90%. Common yellow or "alpha" brass is about 60% copper and 30% zinc.
The copper in brass is anti-microbial — it kills germs, a fact that has been known since the rise of the Pharaohs, but how it does so has only recently been uncovered.[1]
Most fungi (mold and mildew) and most bacteria cannot survive in contact with brass. In tests on colonies of E. Coli bacteria conducted by the EPA, 99.9% of the colony was killed after two hours of exposure to brass.
Small amounts of other materials may be added to give the brass specific properties.
Antimony or tin retard a form of corrosion known as dezincification which can weaken brass over time.
Manganese makes brass harder and nickel refines the grain structure improving strength.
Aluminum makes the brass stronger and more corrosion-resistant. Admiralty and Naval brasses used in salt-rich maritime environments contain a relatively high proportion of aluminum.
Lead is used to make brass more malleable, less brittle, and easier to form and shape.
In faucets, however, lead is dangerous to human health, and especially dangerous to children because it can leach into the drinking water that passes through the faucet.
According to the Environmental Protection Agency (EPA), lead can cause slowed growth, learning problems, hearing loss, anemia, hyperactivity, and behavior issues.
Before 2014, brass in a faucet could contain as much as 8% lead and still call itself lead-free. Now the maximum lead content in a faucet is 0.25% (1/4 of 1%), basically just a bare trace of lead.
To ensure the absence of lead in the brass inside a faucet that is in contact with the water passing through the faucet, the faucet must be tested in a laboratory and certified lead-free. If it is not certified, it cannot be legally installed in a drinking water system.
Keeping Faucets Safe To find out more about how faucets are testeed and certified for safety, see Keeping Faucets Safe & Reliable
To comply with the new restrictions on lead, today's faucet brass uses other additives to ensure malleability. The most common substitute materials are bismuth and silicon.
Bismuth is similar to lead – right next to lead on the periodic table of elements – but it is not harmful to humans. Bismuth, however, is expensive. It is 300 times rarer than lead, even rarer than silver, which is the reason that bismuth-brass alloys are considerably more expensive than leaded brass.
Bismuth has several other problems. It is, unlike lead, a brittle metal, and requires a more precise casting process to preserve the of brass. The result of improper casting is illustrated by a 2012 recall by the Consumer Product Safety Commission of 63,000 azimuth-brass ball valves made in China for use in natural gas pipelines. They were much too brittle resulting in cracks and dangerous valve failures.
Bismuth is also an environmental issue. Brass alloyed with bismuth cannot be easily recycled with non-bismuth brass and must be kept separate to avoid cross-contamination of the materials.
Silicon has somewhat similar recycling issues, but not as severe. Some alloys can be recycled with ordinary brass. Its chief advantage is that it is plentiful. It is not, however, less expensive.
Silicon-brass is considered a high-strength brass. The silicon increases resistance to wear and corrosion. Its disadvantages are that it requires a higher casting temperature than ordinary brass and its hardness makes it much more difficult to machine.
Plumbers don't care for it because it requires a hotter torch and special techniques to solder without which "cold" solder joints may spring a leak.
Nonetheless, it is increasingly popular among faucet manufacturers. One alloy, Eco-brass™ (C69300), is especially formulated for plumbing fixtures.
The other common metal material for faucets is stainless steel.
Photo: Moen, Inc.
Stainless steel is popular in kitchen faucets to exactly match stainless steel kitchen sinks. This is the Notch contemporary kitchen faucet.
Steel is harder than brass and has a higher melting point, making it more difficult than brass to cast and machine.
But, it contains no lead, which in today's regulatory environment is a big plus. And, because it is stronger, castings can be thinner, saving on material.
The stainless steel used in faucets, 304 or 316 stainless contains 18% chromium and 8-10% nickel.
The nickel gives the steel a particular crystalline structure which increases its strength and malleability. Chromium (or chrome) helps the steel resist corrosion. A small amount of molybdenum (2-3%) is added to 316 steel to better resist acids.
Both alloys are austenitic steels, meaning they are low- or non-magnetic.
Stainless 304, known as "food grade" stainless, is by far the more commonly-used alloy for making faucets. However, 316 stainless, known as "marine grade," has superior resistance to pitting, corrosion, and staining, particularly in acidic or salt environments.
For kitchen faucets, 316 is considered the better material, but it is more expensive. Only a few manufacturers use it in their faucets.
switched from 304 to 316 stainless in 2019. sells stainless kitchen faucets made in Italy by Super Inox S.R.L. These faucets are also 316 stainless.
To make things a little more confusing, there are actually two commonly used grades of 304 stainless. The more widespread is 18/8, representing the proportion of chromium and nickel in the alloy: 18% chromium and 8% nickel.
Stainless steel faucets are usually made from 18/8 stainless but some are made from 18/10 stainless, a slightly better grade containing 10% nickel. It is commonly used to make knives, fine cookware, flatware, and restaurant-quality sinks. The added nickel makes the alloy a little harder, able to take a higher polish and, for knives, a sharper edge.
Some faucets, made primarily in Asia, contain a lower quality stainless. As a buyer, you should always look for a certification that the steel used in the faucet is 304 (18/8 or 18/10) or 316 steel. Just the word "stainless" is not enough.
Faucets can be made from a zinc alloy. The best known is an alloy called ZAMAC (for its metal content: Zinc, Aluminum, Magnesium, And Copper) or ZAMAK developed by the New Jersey Zinc Company in 1929.
The original use of this "pot metal" was to replace more-expensive brass in applications where the strength of brass was not needed but its corrosion-resistant properties were.
It is commonly used in the manufacture of die-cast objects such as children's toys, model trains, locks, cabinet pulls and knobs, zippers, plumbing fixtures, including faucets, and, as its nickname suggests, cooking pots.
It is a distinctive metal, dull and gray but can be plated with chrome or another finish metal to make it indistinguishable from a brass faucet.
In the past the material's principal use was the manufacture of economy faucets, but with the advent of severe lead restrictons in brass and the soaring cost of lead-free brass, its use has expanded.
Most faucets that are made of zinc will say so on the box, sometimes indirectly.
The phrase "All-Metal" on the box tells you that parts of the faucet contain at least some zinc. If it's all brass, the box will say "All Brass".
However, some companies can get crafty with their terminology. For example
We have found that the best way to check for zinc is to get a peek inside the faucet. This may require one guy to wield a screwdriver and another to distract the store clerk.
Removing the handle for a quick look inside the casting where it joins the stem often tells the tale. If it's gray metal, the casting is zinc, if it's "coppery", it's brass.
A glance up the spout may also help reveal the faucet's composition, and does not require any disassembly. A penlight is helpful here. A dull gray spout is zinc. If it's brown, green, or "brassy", then it's brass.
Zinc and its alloys are not all bad, however.
In the body of a faucet or its spout — any part subject to water pressure year after year, zinc and zinc alloys are highly suspect.
But, ancillary parts such as handles, base and wall plates, and other trim pieces can be made of a zinc alloy without compromising the quality of a faucet. These parts do not need the strength of brass and zinc can be used to save the cost of the more expensive brass, shaving a few dollars off the retail price of the faucet.
Likewise, in core and shell faucet construction (see more about this new form of faucet building below), what was once the body and spout of the faucet is just a non-structural decorative shell that is not under pressure. Zinc is increasingly being used in shell manufacturing. It takes finish as well as brass and sometimes better, and, according to its adherents, can be more precisely cast and forged.
Companies using core and shell technology like have now converted most of their shells to a zinc alloy.
Plastic faucets have specialized uses. Examples are in laboratories and very saline coastal environments where corrosive chemicals or salt-laden air might damage a metal faucet.
They are also common in RVs. In this environment, plastic faucets can last a long time. RV faucets are fed from an overhead tank and are not subject to much water pressure. Plus, they are used only a few weeks or months out of a year.
But, for sustained residential use in a bathroom or kitchen under household water pressure, a plastic faucet is not a good choice.
Typical static household water pressure is between 40 and 60 pounds per square inch (psi). (Most experts suggest that 50 psi is the most comfortable pressure, and if your water pressure is regularly over 50 psi, you might consider installing a pressure regulator.)
Under certain circumstances, however, such as shutting a faucet suddenly, water pressure can surge to well over a whopping 200 psi.
Plastic faucets simply cannot handle that sort of abuse year after year.
In addition, there are the problems caused by dissolved minerals.
Household water contains dissolved minerals. Among these are magnesium, limestone, iron, silica, and even granite. The types and quantity of minerals vary depending on where you live. But, if you have "hard water", then your water contains lots of minerals.
When water flows through your faucet some of these minerals are left behind as very hard, rock-like, deposits.
In your bathtub or sink these are known as "limescale" or "mineral deposits" and they are the very devil to get rid of after they have built up for a while and etched into the fixture material.
They behave the same way inside your faucet where you can't get at them or even see them. They grind away at the internal moving parts of your faucet, wearing them down over time. Brass and steel can handle the abuse for years and years without failing, plastic cannot.
However, In parts of a faucet not under pressure and not subject to mineral buildup, plastic, like zinc, has a place, (although zinc alloys are a better choice). It can replace expensive brass in baseplates, handles, and other components that are not pressurized,
Plastic has also become almost universal in and housings for some cartridge valves. In these applications, they have worked very well, which is a little surprising. One of the tests that cartridges must survive in order to be certified is a surge test in which the plastic cartridge must survive a pressure surge of a whopping 500 psi for one minute without deforming. (But, see Anatomy of a Failed Cartridge, below).
Unfortunately, however, plastics have also become common in the spray heads ("wands" in the faucet-speak) of kitchen faucets
Manufacturers began switching from metal to plastic wands a few years ago for three reasons:
It is also true, however, that plastic fails more often than metal wands. But, it has now become almost unavoidable.
Even upscale faucet companies like have shifted to plastic wands. While the wands have gotten better, they are not yet on par with metal wands when it comes to longevity.
The sure cure for a wand that is too hot to hold is to dial down the water temperature. There is nothing in the kitchen that actually needs to be rinsed in scalding water.
If you have a choice – and often you will not have a choice if you are to get the look, features, and price you prefer – opt for a metal wand.
There is one form of plastic that does work and works well in faucets. It is cross-linked polyethylene, commonly known as PEX.
PEX has been used with good results to replace copper water pipes for over 30 years. It is recognized by all national plumbing codes as a suitable material for water channels. It is, in many ways, better than copper because it is a lot less expensive, easier to install, and is much less likely to burst from freezing.
It has only very recently begun to be used in faucets, largely in response to the very low lead requirements of the Safe Drinking Water Act effective in January 2014.
Three basic steps are required to manufacture a faucet: forming, refining, and finishing.
Finishing is treated in detail in part 5 of this series: Faucet Finishes. Here we will be looking at the first two steps: forming and refining.
Since almost all faucets a made from metal, forming a faucet is a process of shaping metal into a rudimentary faucet. In most faucet factories the process is highly automated. Machines controlled by computers do most of the work.
The processes most often used to form faucets are casting and forging.
Casting involves pouring molten metal into a mold or die in the shape of the faucet part to be formed, then allowing it to cool and harden.
Casting had its advantages and drawbacks.
Advantages include the ability to create intricate detail not available from other forming methods. Disadvantages include potential defects in the casting that can result in eventual failure. The most common of these are voids and cracks that can weaken the casting. These are often invisible to the naked eye but can be detected through ultrasonic testing.
The earliest process for casting metal used sand molds. They are still commonly used for small runs even in production facilities.
Once an object to be used as the "pattern" for the casting is selected (or created, often out of wood), a special fine-grained sand called "greensand" is poured into a box called a "flask." The sand is alightly moistened so it will adhere.
The flask is made in two parts. The bottom half, called a "drag", is first filled with sand and tamped. The pattern is then embedded in the sand.
The top part of the flask called a "cope" is also packed with sand to complete the mold. It is attached to the drag. The two halves of the mold are separated and the pattern removed leaving a void in the sand in the shape of the part to be cast.
By reassembling the mold and then filling the void with molten metal through a channel (or "sprue") made in the sand the pattern is precisely duplicated in metal. (To see a sand mold being made, watch this video.)
The disadvantage of sand casting is that it is relatively slow. The mold is destroyed in the casting process and has to be made over and over again for each casting. It produces a fairly rough, granular surface (See the image below) that requires considerable refinement after casting to produce the finished object.
However, sand casting has the advantage of being scalable. It can be used to make a single casting or stepped up for small production runs of a few hundred pieces.
Many manufacturers of high-end faucets made as ordered in ones and twos or in relatively small batches prefer sand casting. It does not require a major investment in expensive metal dies that can cost thousands of dollars each.
Most production casting is what is called die casting. It uses metal molds or dies made from a steel especially formulated to be very hard and resistant to wear. These can cast many thousands of faucets before they wear out and need to be replaced.
Dies are made in two halves that are clamped together to make the casting. Where the halves meet is called the parting line.
The die-casting process used by most manufacturers is called cold-chamber casting. In contrast to hot-chamber casting, the casting metal is melted outside of the machine.
In the much faster hot-chamber casting, the metal is melted inside the machine, but hot-chamber casting is not possible with metals having a high melting point like the brass and zinc alloys used to make faucets.
To make the casting, a precisely measured amount or "shot" of the molten metal is fed into an ejection chamber. The shot is then driven into the die by a piston, allowed to cool, then the dies are separated to retrieve the casting.
A second common process for making faucet parts is forging, a method of forming in which solid metal is forced into a die under extreme pressure.
Forging is perhaps the oldest process known to man for shaping metal into useful objects.
Long before mankind learned to make fire hot enough to melt metal, smiths werd forging metal with hammer and anvil. Power hammers are still used in forging, primarily for shaping steel. Hydraulic presses are more common for forging the relatively softer metals used to make faucets.
In die forging, a slug of metal is pressed into a die that has the shape of the item to be forged. To facilitate the process, the metal is often heated to what is called its forging temperature. Heating softens the metal so it more easily conforms to the shape of the die.
Often a metal's forging temperature is just a few degrees lower than its melting point. Most alloys of brass, for example, soften at around 1,500°F (815°C) and melt at 1,710°F (930°c).
Nevertheless, because metal does not need to be melted and then cooled, forging is faster than casting. It also tends to strengthen the forged part by aligning the grain of the metal to follow the shape of the forging.
Its disadvantage is that forged parts are often made in two pieces and then joined by soldering, brazing, or welding. The joint is usually weaker than the forging itself and more likely to fail under water pressure.
Click to watch a video of faucet parts being forged on a forging press.
Some faucets are neither cast nor forged. They are machined out of a solid block of raw metal. These are called monoblock faucets.
These tend to be very plain contemporary designs simply because elaborate designs are difficult to create using the process. Channels inside the faucet are borings rather than being created by casting or forging.
Monoblock faucets are considered by many to be the most structural sound of all faucets because there are no seams.
A newly formed faucet is usually far from ready for the finishing process. It needs to be refined.
Much of refinement is merely a process of cleaning up a rough casting.
When it emerges from the casting process, a faucet part is attached to a sprue, extra metal that formed in the channel used to deliver the metal to the mold.
There may also be flanges of metal where it oozed out of the parting line where two halves of the mold came together.
All of this has to be trimmed away.
Then the rough surface of the casting has to be ground and polished to get it ready for finishing. In small shops, this may be done by hand. But, in most production facilities it is done by a robot.
To watch a robot grind and polish a faucet through the many steps required, view this video.
Many parts of a faucet require threaded openings and precise mating surfaces. Providing these features is the province of machining or milling.
In former years, machining was done by skilled machinists who might apprentice for many years before they were considered accomplished enough to be trusted with this critical task.
In some small shops, a machinist may still do this work. But, in production facilities, it is all done by computer-controlled machinery.
The need to eliminate lead in faucets has produced a mini-revolution in how faucets are made.
In conventional faucet construction, function and decoration are combined. The body and spout of the faucet do double duty. They give the faucet its appearance. But, they also provide the channels through which water flows.
With core and shell construction, the channels that carry water (the core) are separate from the body of the faucet (the shell).
The two major U.S. faucet companies, have both adopted core and shell.
In Moen's faucets, water is routed through copper tubing inside the faucet. Delta uses PEX tubing. This tubing, not the faucet itself, channels water and contains the water pressure.
The body of the faucet becomes just decorative trim that hides the core from view. Since water never touches the shell, it cannot possibly pick up any lead.
Core and shell design helps keeps the cost of lead-free faucets under control. It also has several advantages over conventional faucet construction.
From the point of view of the mechanics involved, a basic faucet is nothing more than a valve that controls and directs the flow of water through a tube. The main components are the valve itself, a body to contain the valve, a handle to operate the valve, and a channel through which the water flows. … (Continues)
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