Kitchen Sink Materials Compared: Stainless, Fireclay, Cast Iron, Composite and Copper

A kitchen sink takes boiling water, dropped pans, knives, acids and abrasive cleaners every day, so the material matters more than the look. This page compares the five materials you will be offered and explains the terms on a stainless steel spec sheet. For bowl layouts and mounting, see sink styles and configurations. For the plumbing decisions around the sink, see kitchen sinks, faucets and plumbing.

Sink materials at a glance

Stainless steel: gauge, grade and what else to look for

Gauge

Gauge is a thickness scale that runs backward: the lower the number, the thicker the steel. Under the United States standard gauge for sheet steel, set out in federal law at 15 U.S.C. 206, 16 gauge is 1/16 inch (0.0625 inch) and 18 gauge is 1/20 inch (0.05 inch). The same table lists 20 gauge at 0.0375 inch and 22 gauge at 0.03125 inch, which is half the thickness of 16 gauge.

Those are nominal figures, and mills work to tolerances, so the sink in the box will not measure exactly that. What the numbers tell you is the order of things. Residential sinks worth buying are 16 or 18 gauge. Thinner steel drums when water hits it, flexes under a disposal and dents when a heavy pot is dropped.

Grade

The other figure on the sheet is the grade. Type 304 is an austenitic stainless steel with approximately 18 percent chromium and 8 percent nickel, which is why it is often labeled 18-8 or 18/8. The National Institute of Standards and Technology describes it in those terms. Chromium is what makes the steel resist rust, and nickel adds corrosion resistance and toughness. ASTM A240 is the specification that sets the exact composition limits for stainless sheet. If a sink's listing gives a gauge but no grade, ask.

Beyond the two numbers

• Sound deadening. Good sinks have thick rubber pads bonded to the outside of the bowl walls and bottom, plus a sprayed undercoating that also limits condensation in the cabinet. Turn the sink over in the showroom. Large pads on every side are what you want.
• Finish. A brushed or satin finish hides scratches. A mirror finish shows every one.
• Corner radius. Sharp, square inside corners look crisp and give a flat floor to the edges, but food collects in them. Slightly rounded corners are easier to wipe.
• How it was made. Square-cornered sinks are folded and welded from sheet, so the walls stay at full thickness. Drawn sinks are pressed from one sheet, with soft curves.
• Drain slope. The bottom should fall toward the drain so water does not pool. Channels pressed into the floor help.

Fireclay

Fireclay is ceramic clay shaped, glazed and fired at high temperature until clay and glaze fuse. The result is a dense, glossy surface that resists stains, acids and heat and does not show water spots the way steel does. It is the material behind most white apron-front sinks.

What to know before you choose it:

• Chipping. A cast iron pan dropped on the edge can chip the glaze or, rarely, crack the sink. A bottom grid and some care with heavy cookware prevent most damage.
• Size variation. Fired clay shrinks unevenly, so each sink differs slightly from the catalog dimensions and may not be perfectly square. The cabinet and countertop are fitted to the actual sink, which should be on site before templating.
• Weight. It needs a reinforced sink base.
• Glassware. A hard sink is less forgiving than steel when a glass slips.

Enameled cast iron

This is a cast iron body coated in a thick layer of porcelain enamel. The enamel is glossy, comes in many colors and has a depth that paint cannot imitate. The iron holds heat, so a sink of hot water stays hot.

It behaves much like fireclay, with two differences. It is heavier still, and beneath a chip there is iron, which rusts if left exposed. Clean it with non-abrasive products, because scouring powders slowly dull the gloss and a dulled surface holds stains. Drop-in cast iron sinks with a self-rimming edge are among the easiest heavy sinks to install, since the countertop carries the weight.

Granite and quartz composite

Composite sinks are molded from crushed stone bound with resin. The surface is matte and slightly textured, the color runs through the body, and the material is quiet without any padding. Composite stands up well to scratches and to hot pans.

• Color choice is the main decision. White and cream show tea, coffee and tomato stains and need regular cleaning. Black and dark gray hide stains but show a pale haze from soap and minerals.
• Stone content varies between manufacturers and affects hardness. Ask what the sink is made of and read the warranty's exclusions.
• Avoid sudden extremes. Do not pour boiling water onto a sink full of ice.

Copper

Copper is chosen for how it looks and for the fact that it changes. Bare copper darkens with exposure to air and water, then brightens again wherever lemon juice, vinegar or tomato sits on it. Over months the surface settles into a mottled brown. Manufacturers call this a living finish.

• Thickness matters here too. Copper is softer than steel, so thin copper dents easily. Copper sinks are also sold by gauge, with lower numbers thicker.
• Smooth or hammered. A hammered texture hides dents and scratches.
• Finish. Some sinks are sealed with lacquer to hold a color. The lacquer eventually wears through in a working sink, and the wear is uneven.
• Cleaning. Mild soap and a soft cloth. Abrasives and acidic cleaners strip the patina.

Copper suits people who like a surface with a history. If an uneven finish would bother you, choose something else.

What to check before you buy

1. Stainless: gauge (16 or 18), grade (type 304), pads on all sides, brushed finish.
2. Fireclay and cast iron: the weight on the spec sheet, the support the manufacturer requires, and the stated size tolerance.
3. Composite: the color under your own lighting, and the care instructions for that color.
4. Copper: gauge, whether it is sealed, and photos of the finish after a year of use.
5. Any material: the minimum sink base cabinet width, the drain position, and whether a fitted bottom grid is included or available.
6. Mounting: whether this material and model can be undermounted with your countertop. See choosing kitchen countertops.
7. The warranty, and what it excludes (chips, stains and thermal shock are common exclusions).

Who should choose which

• A busy household that wants no worry: 16 or 18 gauge type 304 stainless with a brushed finish. It is light, hard to damage and works with every faucet and appliance finish.
• A farmhouse or traditional kitchen: fireclay for a white apron front, or enameled cast iron if you want a color.
• A quiet, modern kitchen with matte surfaces: composite in a mid-tone gray, which hides both stains and mineral film better than white or black.
• A cook who uses heavy cast iron daily: stainless, or composite with a grid. Glazed sinks and cast iron pans are a poor match.
• Someone who wants the sink to be a feature: copper, with eyes open about patina, or a colored cast iron sink. Match its tone to the faucet using mixing metal finishes.

The sink material also affects which faucet and disposal suit it, and heavy sinks change the cabinet order. JDI Construction confirms the sink model with you before the cabinets are drawn and has it on site before the countertop is templated. To plan yours, start at kitchen remodeling in Vancouver.