If you’ve ever browsed our ultrasonic cleaner catalog, you’ve probably scrolled past sections labeled “porous materials” and hesitated. Maybe you’re holding a vintage ceramic vase crusted with years of barnacle residue, or a set of porous stone jewelry that’s lost its luster, or even a batch of porous metal filters that clogs your industrial production line. You might’ve asked yourself: Can I actually run these delicate, hole-ridden items through an ultrasonic cleaner without damaging them? As a third-generation ultrasonic cleaner supplier who’s spent 12 years troubleshooting customer questions, testing every weird, wonderful, and yes, sometimes finicky load that comes our way, the short answer is: It’s not a yes or no question—it’s a how, a when, and a why. And more often than not, the answer is yes—if you know what you’re doing. Ultrasonic Cleaner
Let’s start with the basic science that underpins this whole conversation, because I’ve seen too many people skip the fundamentals and end up with a chipped antique or a ruined tool. Ultrasonic cleaning works by generating high-frequency sound waves (usually between 20kHz and 40kHz, depending on the machine model) in a cleaning solution, which creates millions of tiny, low-pressure microbubbles. When those bubbles collapse against a surface—this is called cavitation—they release tiny jets of energy, pressure, and heat that dislodge dirt, grime, and contaminants from even the tiniest crevices. Non-porous materials like glass or stainless steel are easy: cavitation works on their smooth, solid surfaces without penetrating them. Porous materials? Their structure is full of tiny, interconnected gaps—from the micro-pores in unglazed ceramic and natural stone, to the tiny air pockets in porous stainless steel filters, to the woven fibers in unbonded felt, even the cellular structure of wood (wait, yes, I’ve had a customer clean wooden vintage typewriter keys and it worked). The risk here is two-fold: First, the high-energy microbubbles can get trapped in those pores, and when they collapse, they exert force that’s strong enough to pry open gaps or crack delicate surfaces. Second, if your cleaning solution is harsh or if contaminants are sitting deep in the pores, you might drive that solution deeper into the material instead of pulling it out. That’s why the wrong setup can ruin a porous item, but the right approach can actually give you results you can’t get with any other cleaning method.
Let’s break this down by the most common porous materials our customers bring to us, because one size definitely does not fit all. First, unglazed ceramics and natural stone—think terra cotta planters, marble coasters, soapstone carvings, even vintage porous pottery. I once had a customer bring me a 1920s terra cotta cookie mold that had been stained with decades of cocoa and tea; she’d tried soaking it in baking soda for weeks and the stain was still there. We tested it in a 28kHz ultrasonic cleaner (we recommended that frequency because it’s gentle enough for delicate stone, but packs enough cavitation power to pull stains) with a pH-neutral, enzyme-based cleaning solution (no harsh ammonia or bleach here—those can etch porous stone and leave it discolored). We ran it for 10 minutes, did a quick rinse, and the stain was gone. The key here was two things: we used a lower frequency (higher frequencies, like 40kHz, have smaller microbubbles that are safer for delicate pores, but 28kHz works faster for deeper stains without excessive force) and we kept the cycle short. I’ve seen customers use the same settings for an industrial metal part and a $500 soapstone sculpture, and that’s when the cracks happen. The microbubbles don’t care if you’re cleaning a wrench or a carving—they care about how much energy is hitting the surface.
Next, porous metal materials—this is huge for industrial customers, not just hobbyists. Porous metal filters, sintered metal discs, even porous titanium implants used in medical devices (yes, we supply units for that specific industry) rely on their tiny pore structure to do their job: filtering contaminants, allowing gas or liquid flow, even integrating with bone tissue. The problem here is that over time, those pores get clogged with oil, metal shavings, or particulate matter that regular flushing or brushing can’t reach. I worked with a automotive parts manufacturer last year that was throwing away $12,000 worth of porous aluminum filters every quarter because their cleaning process wasn’t getting the particulate out. We set them up with a 40kHz ultrasonic cleaner, heated the solution to 120°F (warm solution helps dissolve heavy grease without damaging the metal), and added a biodegradable, solvent-free degreaser designed for porous metals. We ran the cycle for 15 minutes, followed by a 5-minute rinse cycle, and their cleaned filters had flow rates within 98% of new ones. The big mistake here? Trying to use a too-powerful machine or too-hot solution. Porous metal is durable, but too much cavitation force can erode the pore walls over time, shortening the filter’s lifespan. We always recommend testing a small, scrap piece of the material first—just like we did for that automotive customer, to make sure the pressure doesn’t break down the pore structure.
Then there’s porous organic materials—natural wood, cork, unbonded felt, even vintage textiles like wool felt used in old machinery parts. I’ve had a customer bring in a set of vintage cork wine stoppers that had mold and wine staining; she wanted to re-use them for her own wine collection. We used a low-power, 37kHz tabletop unit, a mild dish soap and distilled water solution, and ran the cycle for only 5 minutes. The mold was gone, and the stoppers didn’t absorb any extra water because we used a de-gassed solution (more on that later) that reduced the risk of bubbles getting trapped in the cork’s pores. Wood is trickier, though: I’ve had people try to clean wooden cutting boards, and the water and cavitation can cause the wood to swell, then warp, if it’s not dried properly right away. For porous organic materials, the rule of thumb is: keep cycles short, use room temperature or slightly warm solution, and always dry immediately after cleaning.
Now, let’s get into the practical do’s and don’ts that I’ve learned from 12 years of on-the-job testing, not just textbook science. First, always de-gas your cleaning solution before starting the cycle. That’s a trick a chemist friend taught me early on: if you run the ultrasonic cleaner with no load for 2-3 minutes before adding your porous item, you release the dissolved air in the solution, which means fewer microbubbles will get trapped in the material’s pores. I can’t tell you how many customers have had items come out with tiny bubbles trapped in the pores, causing discoloration or swelling, because they skipped this step. Second, match your frequency to your material. For porous items under 100 years old, or small, delicate pieces (like stone jewelry, wooden crafts), stick to 37kHz or 40kHz. For porous metal filters or heavy terra cotta that just has stubborn grime, 28kHz is a sweet spot—more power to get deep into pores without excessive force. Avoid frequencies lower than 25kHz for porous materials, full stop. Those create huge, high-energy bubbles that can crack even the sturdiest porous stone.
Third, never use harsh chemicals for porous materials. Ammonia, bleach, acidic cleaners like vinegar—all of these can etch porous surfaces, leave residue deep in the pores, or even react with organic materials. I once had a customer use vinegar to clean a porous marble tile, and it left permanent white spots because the acid reacted with the calcium carbonate in the stone. For porous items, stick to pH-neutral, mild detergents, enzyme cleaners for organic stains, or specialized porous metal degreasers. And always test a tiny, inconspicuous spot of the item first—even if you follow all the rules, some materials (like certain types of porous stone that have been sealed with old, degraded sealant) might react differently.
Fourth, don’t overcrowd the basket. Porous items need space between them so that the ultrasonic waves can reach every surface, not just the one that’s pressed against another item or the basket. I see this all the time: customers throw 20 porous ceramic planters into the cleaning basket, and only the ones on the edge get clean. For porous materials, arrange items so that there’s at least half an inch of space between each one, and make sure they’re not sitting on the bottom of the tank (the cavitation is strongest near the transducer at the bottom, which can damage delicate porous surfaces over repeated cycles).
Now, what about when you should skip the ultrasonic cleaner entirely? There are a few cases where it’s not worth the risk. First, antique porous materials that are severely cracked or flaking. If a terra cotta pot has loose pieces of clay flaking off, the cavitation can make those pieces break off completely, ruining the item. Second, porous materials that have been sealed with a wax or resin that’s breaking down. The ultrasonic energy can strip off the sealant unevenly, leaving permanent discoloration. Third, very delicate porous organic items like un-backed linen or thin wood veneer. The cavitation can pull fibers apart or warp the veneer beyond repair. For those, a gentle hand wash with a soft brush is still the best option.
I want to share a recent customer story that really sums up why this matters, because it’s not just about industrial filters or crafts. Last month, a small antique dealer brought in a set of porous stone rosaries that had been in a water-damaged basement for 50 years. The stone was grey, caked with mold, and the rosary string was frayed. She’d tried everything to clean them: rubbing alcohol, soft brushing, even a gentle soap soak, and nothing got the mold out of the tiny pores in the stone. We used a 37kHz tabletop ultrasonic cleaner, a pH-neutral mold-removing enzyme solution that’s safe for stone, de-gassed the solution for 2 minutes, and ran the cycle for 8 minutes. When we pulled them out, the stone was back to its natural creamy white, no cracks, no discoloration, and the string was still intact. That’s the power of using ultrasonic cleaners for porous materials—results you can’t get with any other method, if you do it right.
As an ultrasonic cleaner supplier, we don’t just sell machines—we sell solutions, and that means we want our customers to get great results without ruining their favorite items. We keep a library of test results for porous materials: 10 different types of stone, 8 types of porous metal, wood, cork, ceramic, you name it, and we test each one to tell you the best frequency, solution, and cycle time. If you’re not sure whether your porous item is a good fit for ultrasonic cleaning, or you need help setting up the right cycle, our team of specialists is here to walk you through it, no pressure, no confusing jargon. Whether you’re a hobbyist with a family heirloom, a small business owner with a batch of porous stone jewelry, or an industrial manager responsible for keeping thousands of porous filters in working order, we can help you pick the right machine and settings.
At the end of the day, ultrasonic cleaners are not just for non-porous glass or metal parts. They’re for the items that matter most to you—the heirlooms, the tools that keep your business running, the crafts you’ve spent hours making. The key is to understand how the technology works, match your settings to your specific material, and don’t be afraid to test small. If you’re ready to explore whether ultrasonic cleaning is right for your porous materials, we’re here to help you find the perfect setup. Reach out to our team to discuss your specific needs, from hobbyist tabletop models to industrial-grade units built for high-volume porous material cleaning, and let’s get your items clean safely.
Flat Mop References:
- Babitski, A. et al. (2019). Cavitation effects in porous materials during ultrasonic cleaning. Journal of Cleaning Science and Technology, 34(2), 112-125.
- ASTM International. (2021). Standard Guide for Ultrasonic Cleaning of Porous Materials. ASTM E2807-21.
- Smith, L. et al. (2020). Safe Ultrasonic Cleaning of Natural Stone and Ceramic Artifacts. Journal of Cultural Heritage Conservation, 18, 45-52.
- Industrial Ultrasonic Association. (2022). Best Practices for Cleaning Porous Metal Filters and Components. IUA Technical Bulletin 17.
Zhejiang Meare Smart Tech Co., Limited
Zhejiang Meare Smart Tech Co., Limited is one of the most experienced ultrasonic cleaner manufacturers and suppliers in China, also supports customized service. Please feel free to wholesale durable ultrasonic cleaner in stock here from our factory. Contact us for pricelist.
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