I ruined three white t-shirts last summer before I figured out why. They came out of the wash looking clean, but after drying they had orange-brown stains around the collar and cuffs. Not dirt — something more stubborn. I blamed my washing machine, then my detergent, then the water quality in my building.

It was sunscreen. Specifically, the ingredient avobenzone, which reacts with iron in hard water to create rust-colored stains that regular detergent cannot touch. Once I knew what I was dealing with, the fix was straightforward.

Treat the Stain Before It Sets

Time matters with sunscreen stains. The longer the residue sits in the fabric, the more it oxidizes and bonds to the fibers. If you notice a stain at the end of the day, treat it that night — do not toss the shirt in the hamper and deal with it next week.

Rinse the stained area under cold running water first. Flip the fabric inside out and let the water push the sunscreen out of the fibers rather than deeper in. Hot water sets the stain — stick with cold for this step.

Dish Soap and Baking Soda Paste

Mix equal parts liquid dish soap and baking soda into a thick paste. Dish soap is designed to break down oils — and sunscreen is essentially a mixture of oils and chemical filters. Rub the paste into the stain with an old toothbrush using small circular motions. Let it sit for at least thirty minutes, longer if the stain is old.

After soaking, rinse with cold water and check the stain. If it is still visible, make a fresh paste and repeat. Do not put the shirt in the dryer until the stain is completely gone — dryer heat permanently sets whatever is left.

For Set-In Orange Stains: White Vinegar Soak

If you already dried the shirt and the orange stains are locked in, soak the entire garment in a solution of one part white vinegar to three parts cold water overnight. Vinegar breaks down the mineral bonds between the avobenzone and the iron in the water. In the morning, wash normally with the hottest water the fabric can handle, plus your regular detergent and a half cup of baking soda in the drum.

This worked on two of my three ruined shirts. The third was too far gone — but if I had known about the vinegar soak a month earlier, it probably would have been salvageable too.

Switch to Mineral Sunscreen

Zinc oxide and titanium dioxide sunscreens do not cause these stains. They sit on top of the skin instead of absorbing in, and they wash out of fabric with normal detergent. They also do not burn your eyes when you sweat. The tradeoff is the white cast, but modern formulations are much less pasty than they used to be.