A Two-Tonne Secondhand Clothing Importer Had 38 Percent of Orders Returned Because the Musty Smell Would Not Wash Out
Last updated: 7 Sep 2026 | 9 Views |
A true story from a secondhand clothing import warehouse in Bangkok, Thailand
A Two-Tonne Secondhand Clothing Importer Had 38 Percent of Orders Returned Because the Musty Smell Would Not Wash Out
When a smell that arrived with the goods becomes the cost that consumes the entire margin — and washing is not the answer
A secondhand clothing importer in Bangkok was seeing 38 percent of online orders returned because of a musty smell embedded in the fabric that washing would not remove. Here is the real cause of that smell, and how ozone disinfection resolved both the odour and the mould without damaging the fabric.
Wanna, 42, has imported secondhand clothing for five years, receiving roughly two tonnes per shipment in bales, then grading, photographing and selling mainly online, with repeat customers as her core base.
Her hardest problem last year was the return rate, which climbed from about 9 percent to 38 percent within six months. Reading through every return reason, more than three quarters cited the same thing: a musty smell.
What confused her, Wanna says, is that she washes every item before dispatch and dries it thoroughly in the sun. Yet customers still reported an odour, and several said the same thing independently: the smell comes back once they wear it and perspire, or after a couple of days in the wardrobe.
The smell that will not wash out, and why it always returns
Wanna consulted a textile specialist and for the first time in five years understood the problem. Musty odour in secondhand clothing is not surface dirt that can be washed away. It comes from micro-organisms and mould spores embedded within the structure of the fibres.
Secondhand clothing is compressed into bales and shipped for weeks in containers with high humidity and high temperature — ideal conditions for mould and bacteria. Compressed with no air movement, the odour penetrates deep into the fibres.
Detergent removes surface soiling but does not destroy spores lodged inside the fibre. Once the fabric dries the smell appears to be gone, but when it meets moisture again — perspiration, or humid air in a wardrobe — the spores become active and the odour returns.
The specialist's summary was that this is not a cleanliness problem. It is a microbiological one, and solving it requires something that can reach inside the fibre, which washing and sun-drying cannot do at that level.
The costs Wanna had never added up
When she finally worked out what the returns were costing, the damage ran deeper than she had thought. First, shipping both ways, since the shop bears return postage under its stated policy.
Second, returned stock is hard to resell, because once it has been through a customer's hands and back it is rarely in the same condition and must be downgraded. Some pieces end up sold as rag stock below cost.
Third and heaviest, customers who do not come back. Online secondhand clothing runs on regulars who buy every time new stock drops. When a customer returns an item and disappears, replacing them costs far more.
Adding all three, Wanna estimated the damage at roughly 340,000 baht over six months — more than the profit on two entire shipments combined.
What she tried that did not work
First she increased detergent and used strongly scented fabric softener. The scent masked the mustiness for a week, but as it faded the musty smell returned exactly as before — and several customers complained the fragrance was too strong and irritated them.
Second she soaked the clothing in disinfectant before washing. It helped somewhat but had two drawbacks: it takes an enormous amount of time across two tonnes per shipment, and some disinfectants fade colours or damage fabric — which for secondhand clothing sold on condition is direct destruction of value.
Third she dried everything in strong sun for longer. Sunlight kills some organisms at the surface, but inconsistently, dependent on weather, and essentially impossible in the rainy season. Worse, sun fades dark fabrics, which hits the selling price directly.
The turning point came on a visit to a large importer's warehouse, where she saw an enclosed room used to treat stock with ozone before grading. That owner told her simply: you need a gas, because only a gas gets into every part of the fibre.
What she changed, and the result in three months
Wanna asked the World Health Disinfection team to assess her warehouse. After surveying, they proposed two things. First, ozone treatment of every incoming shipment on arrival, before grading and before washing.
The reason is that ozone is a gas, so it penetrates everywhere air reaches — inside the fabric itself, along seams, inside pockets and through stacked piles — places washing and sun-drying cannot reach to the same degree.
Second, regular ozone treatment of the warehouse itself, because the team found high humidity and accumulated odour in the building's structure, meaning treated stock reabsorbed odour when stored there for any length of time.
Within three months the return rate fell from 38 percent to 6 percent. What Wanna did not expect was being able to raise prices on her better grades by around 15 percent, because customers had started telling each other that this shop's stock has no smell.
The real damage
A return rate that consumes the entire margin
A 38 percent return rate means shipping both ways at the shop's expense, stock that must be downgraded, and staff time handling it — roughly 340,000 baht over six months, more than the profit on two whole shipments.
Regular customers lost and hard to replace
Online secondhand clothing runs on regulars who buy every time new stock drops. Customers who return an item and disappear rarely come back, and acquiring replacements costs several times what retaining them would have.
The health of customers and of the grading team
Mould and spores in secondhand clothing are not only an odour issue. They genuinely cause allergic symptoms, rashes and respiratory problems — especially for staff grading stock in the warehouse all day, who receive the heaviest exposure.
Reputation in a market where customers talk constantly
The online secondhand market has customer communities talking on social media all the time, and odour is the single most discussed topic. A shop spoken about badly on that point finds the impression very hard to shift.
Why the usual fixes fail
More detergent and heavily scented fabric softener
This masks rather than solves. The fragrance helps for a week, then the mustiness returns exactly as before, because the spores in the fibre are untouched — and some customers react badly to the strong fragrance itself.
Soaking in disinfectant before washing
It helps somewhat but takes an enormous amount of time across tonnes of stock, and some disinfectants fade colour or damage fabric — which for secondhand clothing sold on condition destroys value directly.
Extended drying in strong sunlight
Sun helps at the surface but inconsistently, dependent on the weather, and is essentially impossible in the rainy season. It also fades dark fabrics, hitting the selling price, and cannot handle large volumes within the time available.
Spraying deodoriser before dispatch
It masks for a few days and usually leaves customers feeling something was concealed. When the smell returns, the dissatisfaction is greater, because customers conclude the shop knew and chose to cover it rather than fix it.
Running a dehumidifier in the warehouse alone
Necessary and worth having, because it reduces further mould growth, but it does not destroy spores already embedded in the fibres on arrival. It prevents things getting worse; it does not fix what is already there.
The problem is inside the fibre, so only a gas will reach it
The principle that made everything clear is that musty odour in secondhand clothing comes from micro-organisms and mould spores inside the fibre structure, not surface soiling. So anything working only on the surface can never fix it permanently.
Ozone is a gas, so it penetrates everywhere air reaches: inside the fabric, along seams, inside pockets, through stacked piles, and into the crevices of the warehouse structure. That is a capability liquids and sunlight simply do not have.
An equally important advantage is that ozone reverts to oxygen once the process ends, so it leaves no residue on the fabric, does not fade colours the way disinfectant soaking does, and leaves no fragrance that some customers react to.
And for a business handling tonnes at a time, ozone treats the entire volume in a single operation, because it treats the whole space rather than each item — which is why large importers use it as standard.
10 reasons ozone disinfection service solves it
1. Ozone is a gas, so it genuinely reaches inside the fibre
This is the decisive point. Musty odour comes from spores embedded in the fibre structure, which liquids reach only at the surface. Ozone, being a gas, penetrates everywhere air reaches — inside the fabric, along seams and through stacked piles.
2. No residue left on the clothing
Ozone reverts to oxygen once the process ends, so nothing remains on garments a customer will wear — unlike disinfectant soaking, which leaves residue that can irritate sensitive skin.
3. No colour fading and no fabric damage
Secondhand clothing sells on condition, so any method that fades colour destroys value directly. Ozone treatment at appropriate parameters does not fade colour the way prolonged strong sun or bleach soaking does.
4. Treats large volumes in a single operation
It treats the whole space rather than item by item, which suits a business receiving tonnes per shipment with limited time before grading and listing — a constraint that makes other methods impractical commercially.
5. Removes both the odour and its cause at the same time
Conventional deodorising works at the endpoint by masking. Ozone works on the cause — the micro-organisms and spores producing the smell — so the odour does not return when the fabric meets moisture again.
6. It can treat the warehouse as well as the stock
Teams frequently find accumulated odour in the building structure itself, so treated stock reabsorbs it during storage. Ozone can be applied to both the goods and the building, which closes the loop across the whole operation.
7. It reduces health risk for the grading team
Staff grading secondhand clothing all day receive the heaviest exposure to spores and fabric dust. Treating stock before grading therefore protects the team at the same time as solving the product problem — a benefit many owners never consider.
8. A professional team assesses the site and sets parameters for your stock
The right concentration and duration depend on fabric types, volume, area and severity. Having an experienced team assess the site matters far more than buying a machine and experimenting without data.
9. A clear safety procedure
Ozone must be applied in unoccupied areas with ventilation for a defined period before re-entry. The World Health Disinfection team follows the safety procedure every time — securing the area, posting notices, and ventilating before handing the space back.
10. It can be scheduled around your shipment cycle
Secondhand import businesses have fairly predictable arrival cycles, so ozone treatment can be planned to match them, becoming a normal step in the workflow rather than a response to a problem that has already occurred.
Before the ozone service
- Return rate up from about 9 percent to 38 percent in six months
- More than three quarters of returns citing musty odour
- Roughly 340,000 baht of damage over six months
- Regular customers returning items and never coming back
- Washing and sun-drying, with the smell still returning once the fabric met moisture
- Grading staff frequently reporting congestion and rashes
After the ozone service
- Return rate down from 38 percent to 6 percent within three months
- Customers telling each other this shop's stock has no smell
- Prices on better grades raised by around 15 percent
- Every incoming shipment treated on arrival as a standard step
- The warehouse treated regularly, so stock no longer reabsorbs odour
- Grading staff reporting clearly improved respiratory symptoms
The service in 3 steps
1. Assess the site and set parameters suited to the stock
The team surveys the warehouse, assessing area, volume per shipment, the predominant fabric types and the severity of the problem, then sets the appropriate concentration and duration — and plans how stock should be arranged so the gas reaches everything.
2. Treat the stock and the space under the safety procedure
Arrange stock with enough space for the gas to penetrate everywhere, secure the area and post notices, keep everyone out during the process, then ventilate for the specified period before handing the space back.
3. Schedule it around the shipment cycle
Plan the treatment as a standard step in receiving every shipment, before grading and before washing, plus periodic treatment of the warehouse itself so odour does not accumulate in the building and transfer back into the stock.
From a real client
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Why the smell always comes back, even after washing
The question secondhand traders ask most is why the smell returns after washing. The answer lies in the nature of fabric. Natural fibres such as cotton and linen have a structure full of tiny voids where micro-organisms and spores lodge and are difficult to wash out.
When the fabric dries, the spores go dormant and produce no odour, so the problem appears solved. When they meet moisture again — perspiration, humid air in a wardrobe, storage in a plastic bag — they become active and the odour returns.
This is why so many customers independently report that the smell came later, which sounds to a seller like a misunderstanding but is in fact microbiologically accurate in every respect.
The correct fix is therefore not washing more thoroughly but destroying the spores inside the fibre — which requires something that penetrates to that level, and is exactly why a gas works where liquids cannot.
Other businesses with the same problem using the same solution
Odour embedded in materials is not unique to secondhand clothing. Dealers in used goods and collectables face it with leather bags, shoes, soft toys and old books — all porous materials that hold odour internally.
Costume and wedding dress hire businesses face it too, because garments are stored used inside non-breathable covers, accumulating musty odour that the next customer receives directly — something that damages reputation badly in that trade.
Secondhand furniture and household goods dealers face the same problem with fabric sofas, mattresses and rugs, which can be surface cleaned but not treated internally by ordinary means.
The principle applying to all of them is that when odour comes from micro-organisms living inside a porous material, anything working only on the surface will never fix it permanently. It needs a method that reaches inside — and gas treatment is the most direct answer available.
Frequently asked questions
Will ozone treatment damage fabric or fade colours?
Not when carried out by a team setting the concentration and duration to suit the fabric types involved. It does not fade colour the way prolonged strong sunlight or bleach soaking clearly does.
Does it leave residue on the clothing?
No. Ozone reverts to oxygen once the process ends, leaving no residue on the fabric — a significant advantage over disinfectant soaking, particularly for customers with sensitive skin or for children's clothing.
Should we wash before or after the ozone treatment?
Treat before grading and before washing, to address the cause at the outset and to protect the staff who have to handle the stock. Then wash normally to remove surface stains and soiling.
How long does it take?
It depends on the area, the volume and the severity, but is generally a few hours per cycle including the ventilation period before re-entry. The team will assess the site and give you a clear timeframe.
Can people be present during treatment?
No. Ozone must be applied in an area with no people and no animals present. The team secures the area, posts notices, follows the safety procedure, and ventilates for the specified period before handing the space back for normal use.
How often should it be done?
For an import business, treat every incoming shipment, which is already a fairly regular cycle. Treatment of the warehouse itself should be periodic, based on humidity and stock turnover — the team will advise an appropriate interval.
Can it be used on other kinds of goods?
Yes. The same principle applies to bags, shoes, soft toys, old books, hire garments, fabric sofas, mattresses and rugs — all porous materials holding odour internally where surface cleaning cannot fix it.
How is pricing assessed?
On area, volume of work, severity and the frequency required. The World Health Disinfection team always surveys the site and quotes before starting, explaining the procedure and the time required clearly.
The problem was never on the surface, and the answer was never washing
The clearest lesson in Wanna's story is that you can solve the wrong problem for years if you diagnose the cause wrongly at the outset. She washed harder, used stronger products, dried longer — none of it wrong, and none of it matched the actual problem.
Once you understand that the odour comes from spores inside the fibre rather than dirt on its surface, the solution is immediately obvious: you need something that penetrates to that level, and only a gas does.
And commercially, the result did not stop at fewer returns. It made higher prices possible — because what customers pay more for is not better clothing. It is confidence that when they open the parcel, there will be no smell.
Talk to the World Health Disinfection team about a site assessment and an ozone treatment plan for your warehouse and stock, scheduled around your shipment cycle.
See the ozone disinfection service and pricing — click here
Call 065-556-6294 or add LINE @whd268
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