Buyer’s guide
Size the tank to the batch you clean, not to the bench it stands on.
A showroom cleaning one customer piece at a time needs 2 to 3 litres. A finishing room cleaning dozens of pieces per cycle needs 10. A casting or polishing house on more than one shift needs 15 to 30. Frequency matters as much as size: 40 kHz for finished jewellery, 28 kHz for casting plaster.
Which tank size do I need?
Find the row that matches what you clean in a normal day. The size in that row is the one to buy.
| Tank size | Who it suits | What goes in one load |
|---|---|---|
| 0.6 L / 0.75 L | A single bench, a designer studio, a gem lab | Loose stones and single pieces |
| 1.3 L / 2 L | A small showroom counter, a gemmologist’s workstation | A few rings, or one chain |
| 2.85 L / 3 L | The usual choice for an independent showroom | A tray of rings, chains or earrings |
| 4.5 L / 6 L | Multi-counter showrooms, repair shops, small manufacturing units | Bangles, statement necklaces, bridal sets |
| 6.5 L / 9.5 L / 10 L | Factory finishing rooms, casting houses after investment | Dozens of pieces per cycle |
| 15 L | Casting and polishing houses on more than one shift | Batch after batch, all day |
| 20 L / 30 L | Large manufacturers, watch factories, dental labs, metal recovery | Large loads, with transducer arrays so the tank cleans evenly throughout |
If a tank is too small, every batch has to be run twice. Over a year that costs more in operator time than the bigger tank costs to buy. Pick the size that takes your normal batch in one load, with the basket in.
40 kHz or 28 kHz?
The cleaner works by shaking the liquid until tiny bubbles form and burst against the piece. A lower frequency makes bigger, harder-hitting bubbles.
40 kHz — finished jewellery
- The standard for jewellery, and the one most buyers want.
- Reaches under prongs and inside chain links.
- Gentler on mounted stones than 28 kHz.
- Start with a short cycle of a few minutes and check the piece.
28 kHz — heavy cleaning
- For casting plaster, investment and heavy polishing compound.
- More force, less finesse — not the setting for mounted stones.
- Plaster and heavy compound take longer than a finished piece.
- Warm liquid loosens them faster than a cold bath.
Most showrooms and workshops clean finished jewellery, so 40 kHz is the usual choice. 28 kHz is only needed where plaster or heavy compound is cleaned every day.
What else to check
Four things change how a cleaner works day to day. Check them on any machine before you buy, not afterwards.
- Heater. Some cleaners warm the liquid and some do not. Warm liquid loosens grease, wax and polishing compound faster than a cold bath, so ask whether there is a heater and how hot it goes.
- Timer. A timer that ends the cycle on its own stops pieces being left in too long, which protects the settings.
- Controls. A knob, a digital display with keys, or a controller that stores settings. Stored settings keep results the same when several people use the machine.
- Emptying the tank. A small tank is emptied by hand. On a large tank, a drain valve saves tipping a full tank to change the liquid.
Choose your cleaner in four steps
Two minutes of arithmetic settles the question better than any brochure.
- Count a normal load. Take the pieces you would put in at one time on a busy day, not the most you could ever need. That load is what the tank is sized against.
- Read your size off the table above. Match the load to a row, and take the tank size on that row. If you are between two rows, take the larger one.
- Pick the frequency. 40 kHz for finished jewellery. 28 kHz for casting plaster and heavy compound.
- Check the controls and the terms. Ask whether the machine has a heater and a timer that ends the cycle on its own, and get the power supply, delivery and replacement terms in writing before you buy.
Still between two sizes?
Tell us what you clean, how many pieces at a time and how often, and we will tell you which tank fits. Write to the sales desk — there is no charge for the advice.
The ST4820 at a glance
The facts for the Semsons Tech ST4820, the ultrasonic cleaner sold on this site.
| Item | What you get |
|---|---|
| Model | ST4820, a table-top ultrasonic jewellery cleaner |
| Tank | 2.3 L, with a slotted basket |
| Frequency | 40 kHz |
| Controls | Digital display with push-button keys |
| Lid | Hinged, with a viewing window |
| Power | Mains lead. It plugs in and runs, with no installation visit |
| Order limit | Up to 10 units per customer per day |
The machine
The ultrasonic cleaner sold on this site is the Semsons Tech ST4820, with a 2.3 L tank at 40 kHz. For another tank size, ask the sales desk what is available.
ST4820 ultrasonic cleaner
- Tank2.3 L, table-top
- Frequency40 kHz
- SuitsA showroom counter, a repair desk or a workbench
- SetupPlugs in and runs
Buying the ST4820
- PriceOn the product page, including GST
- DeliveryFree anywhere in India
- DispatchAbout 10–15 days after the order
- ReturnsNon-returnable; a verified manufacturing defect is replaced within 30 days of delivery
Read next: installation, training and spares covers setup and service, and the glossary explains the terms used here.
Frequently asked questions
What size ultrasonic cleaner should a jewellery showroom buy?
Most independent showrooms run a 2.85 L or 3 L tank, which takes a tray of rings or chains in one load. A multi-counter showroom, or one that cleans bangles and bridal sets, is better with 4.5 L or 6 L. The ST4820 sold on this site has a 2.3 L tank, sized for a showroom counter or a workbench.
Which stones should not go in an ultrasonic cleaner?
Keep out pearls, coral, amber, opal, emerald, turquoise, tanzanite, lapis and malachite, and any stone that is fracture-filled, oiled, dyed or glued. Keep out kundan, polki, meenakari, gold-plated and 1-gram gold pieces, and any piece with loose or worn prongs. Diamonds, rubies and sapphires in a secure setting, and solid gold, silver and platinum, are fine. Ultrasonic cleaning removes dirt, not tarnish.
Is 28 kHz or 40 kHz better for jewellery?
40 kHz for finished jewellery and mounted stones, because it is gentler on settings. 28 kHz makes larger, more forceful bubbles and suits casting plaster and heavy compound. Keep gold-plated and 1-gram gold pieces out at either frequency, because the vibration wears plating away.