Short answer: Like any natural stone sink, onyx needs gentle care. Clean a natural onyx sink with warm water and a pH-neutral stone cleaner, dry it after use, wipe up acidic or colored spills right away, and keep it sealed with a penetrating stone sealer. Skip vinegar, bleach, abrasive powders and scrub pads. With that routine, an onyx sink keeps its glow for years.
The Avorio Cream Onyx Vessel Sink, on view at our Richardson showroom.
What is onyx, and why does it need special care?
The onyx used for sinks and décor is a natural banded stone made mostly of calcite, the same mineral family as marble and travertine. That is what gives it its translucent, glowing layers (we cover the geology in What Is Going Onyx?). Calcite is soft, around 3 on the Mohs hardness scale, compared with roughly 6 to 7 for granite. It also reacts with acids. So onyx scratches more easily than granite and can "etch," which means acid leaves a dull, rough spot on the polished surface.
How do you clean an onyx sink day to day?
- Rinse the basin with warm water after use.
- For regular cleaning, use a soft cloth or sponge with a few drops of mild dish soap or a cleaner labeled pH-neutral and safe for natural stone.
- Rinse well so soap film doesn't build up.
- Dry with a soft microfiber towel. Drying helps prevent hard-water spots, which are mineral deposits that can dull the shine.
What should you never use on onyx?
- Acidic cleaners: vinegar, lemon, citrus cleaners, many bathroom and "lime/scale" removers.
- Harsh or alkaline chemicals: bleach, ammonia and strong degreasers, which can wear down sealer and dull polish.
- Abrasives: scouring powders, magic erasers, steel wool and green scrub pads.
Also watch everyday products. Toothpaste, mouthwash, some soaps, perfumes, hair dye and nail polish remover can all mark the stone if left to sit. Wipe them up promptly.
How often should an onyx sink be sealed?
Sealing doesn't make onyx acid-proof, but it slows down stains by filling the stone's pores. Our sinks are sold unsealed, so seal yours with a penetrating natural-stone sealer before first use, then reseal every 12 months. A quick test: drip a little water on the surface. If it beads up, the sealer is working. If it soaks in and darkens the stone within a few minutes, it's time to reseal. Always use a penetrating sealer made for natural stone and follow the label's directions. Marble and travertine sinks follow a similar routine; see our broader guide, How to Care for a Natural Stone Sink.
The Long Onyx Vanity Bowl – Cream.
How do you handle stains, etches and scratches?
- Water rings or soap film: clean with a pH-neutral stone cleaner and dry well.
- Oil-based or colored stains: a stone poultice (a paste that draws the stain out over a day or two) often works. Test it in an out-of-sight spot first.
- Etch marks: these are surface damage, not stains, so cleaners won't fix them. Light etching can sometimes be buffed with a marble polishing compound; deeper etches are best handled by a stone restoration professional.
- Chips or cracks: call a pro. Onyx is more brittle than many stones, so avoid dropping heavy items into the basin.
Any tips to prevent damage in the first place?
- Keep soap, cosmetics and cleaners on a tray, not directly on the stone.
- Use coasters or a dish under anything that might leave a ring.
- Avoid sudden extreme temperature changes, like pouring boiling water into a cold basin.
Want to see onyx in person?
Seeing this exotic stone's translucence in person is the best way to understand it. Visit the CounterFixtures showroom at 909 N. Bowser Rd., Richardson, TX 75081, Mon–Fri 9–5 and Sat 9:30–1:30. Walk-ins are always welcome, and custom appointments are available at 469-779-9999. You can also browse onyx pieces like the Verdant Veil green onyx double vanity and Translucent Onyx Modern Lamp in our shop.
Verdant Veil: Double Vanity Sink in Green Onyx.
FAQ
Can I use vinegar to clean an onyx sink? No. Vinegar is acidic and will etch onyx, leaving dull spots. Use a pH-neutral stone cleaner instead.
Can I use Windex or bleach on onyx? It's best not to. Ammonia and bleach can strip sealer and dull the polish. Warm water and a stone-safe, pH-neutral cleaner are safer.
How often should I seal an onyx sink? Seal it before first use (our sinks are sold unsealed), then reseal every 12 months. If water soaks in sooner, reseal early.
Is a dull spot on onyx a stain? Usually not. A dull, rough patch is an etch from acid. It needs polishing, not cleaning.
Will hard water damage onyx? Hard water leaves mineral spots that can dull the surface over time. Drying the sink after use prevents most of it.