Sunscreen is important for the health of your skin, but it can make an absolute mess of your clothes — especially your favorite summer whites.

The thing that makes sunscreen stains such a challenge to remove is a complex chemical reaction that occurs between the ingredients in sunscreen, fabrics and water. But an unexpected cleaning product is the secret to eliminating these complicated stains.

Sunscreen is a combination stain that is made up of oil and mineral compounds, which are broken down for stain removal in different ways.

Avobenzone, an ingredient found in most sunblock formulas, is the bad actor that makes sunscreen stains so difficult to remove from clothing, towels, fabric outdoor furniture, etc. “Avobenzone has the propensity to oxidize,” says Wayne Edelman, president of Meurice Garment Care, “which causes the yellow-orange stain.”

To put it another way, when avobenzone mixes with the minerals in water, the orangish stains that result are, essentially, rust stains. If you live in an area with hard water you will experience more severe rust stains caused by sunscreen, because of the mineral content of your local water supply. According to the fabric care experts at Tide, synthetic fabrics are more prone to these types of stains than natural fibers, like cotton, linen or denim.

While it can be difficult to avoid these stains, there are some things you can do to protect your clothing. “Just like perfume, it is best to apply sunscreen and let it dry before putting on clothing,” Edelman advises. But when sunscreen stains do happen on clothing, there is a secret weapon to reach for.

Now that we’ve identified what those yellowish, orangish sunscreen stains are — rust stains — we have the information we need to pick the right stain removing product. By now you may have guessed what it is! (If you haven’t, we’re about to tell you.)

It is rust remover.

Yes! The unexpected cleaning product that removes rust-like sunscreen stains is rust remover. Makes sense, right?!?

Carbona Stain Devils #9 Rust and Perspiration

To treat yellow-orange sunscreen stains, use a rust stain remover designed for clothing, like Carbona Stain Devils #9, which is the formula for rust and perspiration.

Multipurpose rust removers, like Whink Rust Stain Remover, that are formulated to remove rust stains from hard surfaces such as porcelain or iron, can also be used on fabrics.

Because of the chemical reaction avobenzone has to the minerals in water, it is recommended that you treat sunscreen stains prior to laundering — the more sunscreen you can remove before an item of clothing is exposed to water, the less likely those orange rust stains are to occur. “It is recommended to pre-treat any areas that come in contact with sunscreen,” Edelman says. “The stain remover can be applied and brushed gently prior to washing.” Use a laundry brush to work the rust remover into the stain and lift it out of the fabric.

Another way to remove rust stains from clothing is to use a combination of lemon juice and salt.

Using lemon juice and salt is an easy and inexpensive way to remove rust stains from clothing and other textiles. The trick to this method is in the process, which is important — follow these steps to treat rust-like sunscreen stains: