In the middle of sorting the laundry, a formerly unnoticed stain materializes. Or a favorite top has a mysterious spot. In order to get rid of a stain, some detective work is required. Identifying the source of the stain will determine the best way to remove it.

The first step is to examine the color and the staining pattern. Yellow, orange, red or rust-colored stains across an entire load of laundry coming out of the washer may be caused by rusty water pipes. You’ll want a stain remover that is specifically formulated for rust. Or, if on a single garment, a reddish-brown stain may be dried blood. In which case, treat with a stain remover with enzymes, then wash in cold water.

Grey/black pinprick stains that look like they were splattered on a garment could be attributed to mildew. Outdoor cushions, camping gear, and other items that may stay damp for a prolonged period of time are particularly susceptible. To remove these stains, pre-treat the stained area with a stain remover, then launder on the hottest water safe for the fabric. And, if safe for the fabric, consider adding bleach.

Sometimes it’s helpful to establish when the stain occurred in order to determine its source. Stains on the front, neckline, cuffs, etc. are usually acquired while the garment was worn. Often, these stains will be food related. If it’s a small, almost translucent stain, that might be oil or grease from a meal and can be pretreated with a stain remover or a small bit of dish soap before laundering. Or, dark stains at a hemline could be dirt or mud and should be soaked for five minutes before washing in a mixture of a tablespoon of detergent in a gallon of water.

Like with any mysteries, a cold case is harder to solve. The longer a stain has set the harder it may be to remove. Whatever the stain is, take another careful look after running it through the washer and don’t put anything in the dryer with a stain on it. Run persistent stains through the process again, with a stain remover before laundering, and add some bleach if safe for the fabric.