What Starch Really Does to Your Clothes—and When to Use It

Sure, you've heard of starch. And you've seen what it can do to dress shirts. But what actually is it? And how does it differ from the starch in your food? In short, there is no difference. The same starch that you use in your recipes to thicken sauces can help clothing keep its structure. 

So when is applying starch to your garments a wise choice? We went to fabric and laundry care experts to find out when to spray and when to skip.

What Is Fabric Starch?

Starch is most known for its ability to help a garment hold its structure for hours on end for a crisp, clean look. (Think wedding day or prom night tuxedo shirts, starched and pressed in place for the long hours ahead.) "Starch is a natural carbohydrate that comes from plants like corn, wheat, or potatoes," fabric expert Noor de Swart explains. The starch itself is what makes foods like rice and pasta sticky and binding, and the same principle applies to clothing. "On its own it's just a fine powder," de Swart says, "but for clothes it's mixed with water so you can spray or apply it to fabric." 

After drying, a light, protective coating of starch is left on the fibers, preventing creases and embedded dirt from taking hold. "In practice, starch bonds to fabric to smooth it, stiffen it, and help it hold shape," says Tom Ceconi, president of Heritage Park Laundry. Ironing helps set that coating, so that whatever shape that's pressed into the fabric tends to hold for longer.

"Visually, that means cleaner lines, sharper edges, and a smoother finish," de Swart says, "which makes clothes look more polished overall."

The Benefits of Fabric Starch

• Keeps Garments Fresher for Longer: "The coating sits right between the fabric and your skin, which means sweat and oils don't work their way into the fibers as deeply," explains fabric expert Gary Firth. This also goes for those crisply ironed lines. "Iron a shirt without starch and it starts creasing within a couple of hours," says de Swart. "Add starch and that same shirt gets through a full day looking more or less the same as when you left the house."
• Reduces Staining: Once applied and dried, the starch polymers will serve as a barrier on top of fabric fibers. This barrier helps repel stains. While this "won't stop heavy or intense stains from sinking in," Firth says, "it will make everyday dirt easier to brush or dab off."
• Stiffening Effect: "[Starch] also has a stiffening effect, meaning it's great for holding an item's shape and clean edges," says Firth. "Think neat button bands, perfectly flat pleats and smooth hems."
• Easier Ironing: As it happens, starch also makes the ironing process easier. "The iron also glides more smoothly over starched fabric, so you get a cleaner finish in less time," explains de Swart, "which is a bonus if ironing isn't exactly your favorite activity."

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Different Types of Starch

Fabric starch comes in three different formulas: spray, liquid, and powder. All of them will serve to stiffen fabric, create crisp lines, and make your garment more stain-resistant. However, they each have their unique upsides: Spray formulas are the most convenient to apply for a quick ironing, while liquid starch is ideal for uniform coating in the washer, and powdered starch is a cheaper, high-strength option. 

Different garments may respond best to different types of starch application. For example, Firth recommends powder or liquid formula for larger items or those that you might not wash after each use, like a linen jacket or pair of jeans. "A spray starch can be great for stiffening shirt cuffs and collars, or getting really sharp creases into your trousers and workwear," Firth adds.

You also have choices when it comes to how much starch you want to apply to your garment. When a super-stiff shirt collar feels like overkill, go for a lighter application of starch to maintain the garment's structure, while opting for a slightly more relaxed feel.

When to Use Fabric Starch

Starch is most commonly associated with work shirts, though it is also used on a number of other clothing items. "Shirts are the obvious one, especially for work, where they can start to lose their shape pretty quickly without it," says de Swart. However, any garment that relies on structure can benefit from an application of starch. "Collars, cuffs, pleats—anything like that tends to hold up better through the day [with the addition of starch]."

This includes linen jackets, pleated skirts, aprons, and slacks. It is also commonly used on uniforms, wedding or formal attire, and even table linens—anywhere a tailored look matters. "An older garment will also benefit from the smoothing effect of starch on surface fibers, giving extra weight and firmness to lightly worn items," adds Ceconi.

When to Avoid Fabric Starch

For all of its merits, starch is not appropriate for all fabrics and occasions. For starters, delicate fabrics should be handled carefully when using starch, lest they sustain any permanent damage. "Softer and delicate fabrics like silk and cashmere can end up feeling a bit too stiff and lose their soft feel," de Swart warns.

And those with skin sensitivities may also want to steer clear. "It can trigger reactions like contact dermatitis and aggravate other conditions like eczema," says Ceconi. "For this reason, it is not recommended for anyone with sensitive skin or on baby and toddler clothing and bedding." Even if it doesn't trigger allergies, starched clothing can also just be plain scratchy and uncomfortable on the skin, especially when worn for hours on end.

Ceconi adds that excessive starch can also weaken fabric fibers over time. "This may seem counterintuitive because starch binds and stiffens fabric when you use it, but stiff fabric doesn't equate to strong fabric," Ceconi explains. "In fact, stiff fibers are more brittle and prone to damage, which is why heavy starch can shorten the lifespan of a dress shirt."

And while starch can certainly polish up formal clothes, it's not necessary for more relaxed, everyday wear. Hot weather is another consideration, says de Swart. "That stiffness that feels great in winter can feel quite heavy and restrictive when it's warm outside," she says.