What Solution to Use in an Ultrasonic Cleaner
The short answer to what solution to use in an ultrasonic cleaner: plain water plus a water-based cleaning concentrate matched to the job — a mild non-ammoniated formula for jewelry, a degreasing formula for gun parts and carburetors. Never plain water alone (it underperforms badly), and never, under any circumstances, a flammable solvent like isopropyl alcohol or acetone, which can turn the tank into a fire hazard.
That one paragraph will keep you out of trouble. The rest of this guide explains the why — what the chemistry in an ultrasonic cleaning solution actually does, an honest look at DIY options like dish soap and Simple Green, a job-by-job solution table, and the cost math that shows why a proper concentrate is usually the cheapest option per tank, not the most expensive.
Why Water Alone Underperforms
An ultrasonic cleaner works by cavitation: sound waves rip microscopic vacuum bubbles into the liquid, and their collapse scrubs every submerged surface (the full physics is in how ultrasonic cleaners work). Water fights this process twice:
- High surface tension. Water molecules cling to each other, resisting both the formation of cavitation bubbles and the penetration of liquid into tight crevices — the exact places you bought the machine to reach.
- No soil suspension. Water cannot emulsify oil. Whatever grease cavitation knocks loose floats in the bath and promptly redeposits on your parts and tank walls.
A real solution for an ultrasonic cleaner fixes both. Surfactants slash surface tension so bubbles form readily and the ultrasonic cleaning fluid wets every thread and blind hole. Detergent builders and emulsifiers grab loosened oil and hold it in suspension until you drain the tank. Good formulas add corrosion inhibitors so freshly stripped steel does not flash-rust and brass does not etch mid-cycle — something no kitchen ingredient provides.
The DIY Options, Honestly Rated
Dish Soap and Water
The classic homemade ultrasonic cleaning solution: a few drops of dish soap per gallon of warm water. Honest verdict — it works acceptably for light jobs. Eyeglasses, lightly soiled gold bands, and everyday grime respond fine, because dish soap is, after all, a surfactant.
Its three real weaknesses:
- Foam. Dish soap is engineered to suds, and foam is an ultrasonic killer — the bubble blanket absorbs acoustic energy before it reaches your parts. Overdose even slightly and cleaning power drops visibly.
- Residue. Dish soap leaves a film that needs a thorough rinse; on jewelry it dulls sparkle, on parts it attracts dust.
- No inhibitors. Nothing protects steel from flash rust or brass from etching.
For a deeper dive into DIY ultrasonic cleaner solution recipes — including the ammonia-based jewelry mixes and where each one fails — see the companion piece on DIY ultrasonic jewelry cleaner solutions.
Simple Green in an Ultrasonic Cleaner
Simple Green is a legitimate degreaser and plenty of hobbyists run it. Two cautions, both straight from the manufacturer's own guidance:
- Dilute it. It is sold strong; running it near full strength in a heated ultrasonic bath is overkill and makes rinsing harder. Common practice is roughly 1 part cleaner to 10-30 parts water depending on the soil.
- Watch aluminum. The original formula can darken or etch aluminum with prolonged, heated exposure — Simple Green itself tells users to limit contact time on aluminum and rinse promptly. That is an uncomfortable fit with 30-minute heated carb cycles on aluminum bodies.
It also lacks corrosion inhibitors tuned for mixed metals, so bare steel still wants oil immediately after.
What About a Stronger Ultrasonic Cleaner Solvent?
The searches for "ultrasonic cleaner isopropyl alcohol" are common enough that it bears repeating: the right ultrasonic cleaner degreaser is an aqueous detergent concentrate run warm, not a solvent. Heated cavitation plus the right detergent chemistry dissolves varnish, carbon, and oil that people assume needs solvents.
What Liquid to Use in an Ultrasonic Cleaner, by Job
| Job | Best solution type | Our match | Notes |
|---|---|---|---|
| Jewelry, watches, eyeglasses | Mild, non-ammoniated jewelry formula | Jewelry Cleaner Solution | Safe for gold, silver, platinum, diamonds; skip pearls, opals, emeralds |
| Household mix: coins, dentures, tools, small parts | All-purpose detergent concentrate | All-Purpose Solution | One bottle covers the whole house bench |
| Carburetors, injectors, engine parts | Heated degreasing formula, aluminum-aware | Carb & Parts Cleaner | 140-150°F, 20-30 min; guide: carb cleaning |
| Firearms: slides, frames, bolts, suppressor parts | Gun-specific degreaser with inhibitors | Gun Cleaner Concentrate | Re-oil immediately after; guide: gun cleaning |
| Brass cases for reloading | All-purpose or gun formula, mild | Either of the above | Details in brass cleaning for reloaders |
| Electronics (boards, no batteries) | Low-residue formula, distilled water, brief cycles | All-purpose, lightly dosed | Advanced use: dry thoroughly for days or with heat before power-up |
The Cost Math: Why a Concentrate Usually Wins
The reflex assumption is that a purpose-made ultrasonic cleaner detergent is the expensive option and DIY is the cheap one. The per-gallon math says otherwise, because concentration does the heavy lifting:
| Option | Dilution | Cost of working fluid | Hidden costs |
|---|---|---|---|
| Sylvan Hills concentrate, 32 oz at 18.99 dollars | 1:250 | Makes 50+ gallons — about 0.38 dollars per gallon | None; inhibitors and low-foam surfactants included |
| Gun Cleaner Concentrate, 1 gal at 36.99 dollars | 1:250 | Makes 200 gallons — about 0.18 dollars per gallon | None |
| Dish soap | Few drops per gallon | Pennies per gallon | Foam-weakened cavitation, residue film, rust risk on steel, rewash time |
| Simple Green, diluted ~1:15 | 1:15 | Roughly 0.80-1.50 dollars per gallon at typical retail | Aluminum caution, no mixed-metal inhibitors |
| Ready-to-use "jewelry cleaner" bottles | None — pre-mixed | Often 8-15 dollars per quart, i.e. 30-60 dollars per gallon | You are paying to ship water |
Read that last row twice: pre-mixed, ready-to-use ultrasonic cleaner liquid is the genuinely expensive option, often 100 times the per-gallon cost of a 1:250 concentrate. The best ultrasonic cleaner solution strategy is almost always a concentrate — 1.25 fl oz (about 2.5 tablespoons) per gallon of water, mixed fresh when you need it. A typical 2-liter benchtop tank costs roughly twenty cents to fill.
Mixing, Storing, and Knowing When the Bath Is Spent
A few practical habits get the most out of whatever ultrasonic cleaning solution you settle on:
- Mix fresh, by the ratio, not by eye. At 1:250 the margin for error is generous, but doubling the dose does not double the cleaning — it mostly adds foam, and foam absorbs the acoustic energy that does the work. Measure once with a tablespoon and you will have the feel forever.
- Warm water dissolves concentrate faster. Add the concentrate after the tank is filled, stir gently, and let the heater finish the job while the bath degasses.
- Store concentrate sealed at room temperature. A capped bottle of concentrate keeps for years; mixed working solution is best used within a few days.
- Do not leave parts soaking overnight in any detergent bath, especially mixed metals. The cycle is the cleaner; the soak is just exposure.
How do you know the bath is spent? Three signs, any one of which means drain and remix: the solution has gone visibly murky or has an oil sheen on top, parts come out with a haze that was not there last week, or cycle times have crept up for the same soil. Spent ultrasonic cleaner liquid is not just weaker — it actively redeposits the grime it is carrying onto each new load. Drain the tank, wipe it with a soft cloth (never abrasives on the stainless), and refill.
How to Dose and Run Whatever You Choose
- Fill the tank with water to the fill line.
- Add concentrate at the labeled ratio — for ours, 1:250.
- Heat to 120-140°F and degas 5-10 minutes with no parts.
- Load parts in the basket (never on the tank floor) and run the time for the job.
- Rinse in clean water, dry completely, and oil any bare steel immediately.
The complete procedure, including the aluminum foil power test and a troubleshooting checklist, is in how to use an ultrasonic cleaner.
Bottom Line
What solution to use in an ultrasonic cleaner comes down to three rules. Always aqueous, never flammable. Match the chemistry to the job — mild and non-ammoniated for jewelry, degreasing formulas for carbs and guns. And buy concentration, not water: a 1:250 concentrate turns a 19 dollar bottle into 50 gallons of working fluid with corrosion inhibitors and low-foam surfactants that no DIY ultrasonic cleaner solution recipe can match.
Browse all four made-in-USA formulas in the ultrasonic cleaner solutions collection, or see every formula’s dilution ratio and price per ounce on the product page.
