Mold stains are very unsightly and won’t disappear in the wash. But the good news is that the situation can be salvaged if you know what to do! There’s no need to throw away clothing with mold stains!
Small mold spots can be removed at home, but if you’re dealing with larger, stubborn stains, it’s worth taking the garment to a dry-cleaning professional (that is, if you can still find one who knows how to handle it). Be cautious with the tricks spreading on various gossip sites! Using strong chemicals in particular can easily lead to ruining an otherwise salvageable piece of clothing. Let’s also be honest: if the mold has deeply penetrated the fibers of the fabric, then nothing will help—except perhaps a vinegar-soaked pair of scissors…
Textbook Recipes
István Inzelt, in Vegyi receptek (in English: Chemical Recipes, published: Műszaki Könyvkiadó, Budapest, 1967), writes the following:
If the fabric itself has not yet been damaged, immerse the mold stain first in a sodium thiosulfate solution, then in an acetic acid solution; the finely dispersed sulfur that precipitates in the latter kills the mold fungi.
Fresh mold stains can be removed from underwear by soaking for a few hours in vinegar. Older stains can be treated by first washing with soap, then soaking in a diluted bleach solution (Hypó), and finally rinsing with a weak solution of tartaric acid (20 g per liter of water). For quick cleaning, rubbing with a solution that contains
1 part salicylic acid
dissolved in 4 parts denatured alcoholoften works well.
From wool fabrics, mold stains can be removed by washing in a fatty alcohol sulfate solution, soaking in hydrogen peroxide that has been slightly alkalized with a few drops of ammonia and diluted threefold with water, followed by thorough rinsing.
For colored fabrics that cannot tolerate bleaching agents (such as bleach or hydrogen peroxide), you can use a solution containing 3 parts ammonium carbonate and 7 parts table salt dissolved in 90 parts water. Immerse the material in this solution, then dry it in sunlight. The same method can also be used to remove mold stains from paper.
It should be noted that sulfur treatment only kills the fungus, but does not remove the stain. After treatment, stain removal must still be carried out.
The cell walls of mold fungi are made of glucans and chitin. Chitin—the same substance that forms the exoskeleton of insects—is insoluble in water, dilute acids, and alkalis. It only hydrolyzes when heated in concentrated acid, which is not an option here because boiling the fabric in concentrated acid would dissolve the material itself.
So the harsh truth is that mold can be killed, and then either removed mechanically (by washing, scrubbing, brushing, etc.) or faded enough so that, although it remains, at least it is no longer visible.
Soaking and Washing
Instead of a bleach solution, you can also use Domestos. Traditional household bleach and Domestos both contain roughly 4–4.5% sodium hypochlorite and 2–5% sodium hydroxide, as well as a small amount of table salt (a byproduct of the manufacturing process). Both have a pH of 10–11, making them strongly alkaline. Domestos also contains a surfactant (a foaming coconut-based detergent—derived from coconut oil), which makes it more effective at dissolving greasy dirt.
Sodium hypochlorite quickly and easily dissociates in water as follows:
NaOCl → Na⁺ + OCl⁻
The disinfecting and bleaching effect comes from the hypochlorite ion (OCl⁻), more specifically from the nascent oxygen released during its decomposition. Nascent oxygen is highly reactive and an extremely aggressive oxidizing agent that breaks down materials. It doesn’t actually remove the stain; instead, it decolorizes it by oxidizing the colored compounds.
Sodium hypochlorite is not a stable compound; over time, it decomposes into sodium chloride and oxygen. This is why bleach cannot be stored for longer than 3–4 months—even in a sealed bottle, it eventually loses its effectiveness.
Domestos should only be used in diluted form for stain removal! Add two tablespoons of Domestos to 1 liter of water. Soak the garment in this solution, then slowly heat the whole mixture to 60 °C. During this process, the mold stain will disappear. This method should only be used on white fabrics, as it will bleach colored fabrics.
Clorox bleach is the same compound as regular household bleach, just more expensive, and on paper has a slightly higher sodium hypochlorite content (5–6.5%). The reason we say “on paper” is that the exact amount can only be determined by laboratory testing since the compound degrades over time—eventually leaving almost nothing active. Clorox can be used to remove mold stains in the same way as Domestos or regular bleach, but of course only on white fabrics.
It is important to note that nascent oxygen needs time to break down contaminants, so these agents must be allowed to work.
A traditional home method for removing mold is soaking in vinegar, which not only removes the stain but also eliminates the unpleasant musty odor. Here’s the recipe: add 200 ml of table vinegar (6–9%) to 10 liters of water. Soak the garment in this solution for 1–1.5 hours, then wash by hand or in the washing machine. Don’t worry—the vinegar smell disappears during drying.
Smaller Stains and Items That Cannot Be Soaked
Vanish stain remover contains hydrogen peroxide, meaning its active agent is also nascent oxygen. Vanish is quite diluted and less aggressive than chlorine-based agents or concentrated hydrogen peroxide. It can be used on silk, wool, or colored fabrics, but always test it on an inconspicuous area first to ensure the material can tolerate it and that it won’t remove the color or leave marks. Some hair-bleaching creams also contain hydrogen peroxide; after a color test, these can also be used for stain removal.
Ammonia solution (ammonium hydroxide) can also be used to kill mold and eliminate musty odor. Apply the ammonia solution generously to the surface with cotton wrapped around a skewer and let it work for twenty minutes. Repeat the treatment two or three times if necessary, then rinse the surface with clean water or wipe it thoroughly with a damp cloth. It’s important to work in a well-ventilated area because the ammonia gas released from the solution has a very unpleasant, pungent smell, is irritating, and is also toxic.
Similarly, lemon juice mixed with table salt can be used. Add enough finely ground salt to the lemon juice to make a thin slurry. Apply this to the surface and let it dry. Then wash the garment as usual. Baking soda mixed with a little water to form a paste can be used in the same way. These two methods are not as effective as ammonia, but the ingredients are always available in any household and are not dangerous. The downside is that the fabric must be thoroughly washed afterward, as the chemicals can remain in the fibers, and lemon juice can cause ugly brown stains when exposed to heat (e.g., during ironing). In contrast, ammonia evaporates on its own, so washing is only necessary to remove the mold residue.
Older books also recommended turpentine for cleaning delicate fabrics. Carefully dab the mold stain with a cotton ball soaked in turpentine. Then sprinkle the area with powdered chalk or talcum powder (baby powder), cover it with a paper towel, and iron over it. Finally, wash the fabric as usual. This chalk method is a very old stain-removal trick that can also be used on its own without turpentine; it can remove other stains, such as sweat marks. If the surface cannot be washed (e.g., upholstery), simply brush or vacuum it afterward.
Oxygen-based bleaching is not only useful for mold stains but also for removing colored ink stains, aniline dyes, fruit stains, grass marks, wine, beer, coffee, and cocoa residues. However, it cannot be used for grease stains, milk stains, blood stains, urine stains, oil paints, rust stains, or candle wax. Potassium permanganate (commonly known as “Condy’s crystals” or “KMnO₄”) solution can also be used as an oxidizing agent. Permanganate is very effective for breaking down organic dyes*, but its aqueous solution is an intense purple color (pink when highly diluted) and leaves a brown stain when dry. For stain removal, you can use it by decolorizing the treated area afterward with a sodium sulfite solution containing a little hydrochloric acid.
* This is why organic permanganate complexes are used for oil decolorization, where the goal is to oxidize Sudan Red dye used to color heating oil without igniting the oil itself. Newspapers once claimed that “the oil was bleached with sulfuric acid,” which is nonsense because if you add sulfuric acid to diesel fuel, it will explode and cause a fire visible from miles away (and yes, it has happened). Potassium permanganate is an ionic compound that dissolves well in water but poorly in nonpolar solvents, so for oil treatment, potassium permanganate is not used directly—instead, an organic permanganate complex is employed.