When it comes down to basic self care practices, people pretty much have it all down to a science. But when you stop to really think about what you’re doing, questions get raised: should you actually wash your legs? How do you shave your legs, really? Then another question like that popped up when I met with Arnaud Plas, co-founder and CEO of hair company Prose this morning: Am I washing my hair in the right order?

According to him, when using the brand’s highly potent hair masks, you should be using a hair mask before you shampoo. Welp, I’ve been doing it all wrong. Some masks have less-concentrated ingredients which make them totally fine to go on post-shampooed hair because they only need to be rinsed through, yet others that are often dubbed “pre-shampoo treatments” need to be applied ahead of sudsing up because the active ingredients should be washed out. “You want to use our hair mask before you shampoo, because then you’re able to reach 25 percent active ingredients, which is not something you can do if you use a mask after the shampoo,” says Plas.

However, active ingredients aren’t the only reason that you might want to mask ahead of your shampoo. Conditioning agents can certainly help to repair hair and make it happy again, but the flip side is that they can also weigh it down and, in some cases, even make it look greasy or like you should go for another rinse. By applying the mask prior to shampooing, you create good hair days in two ways: The mask acts like primer, so that shampoo doesn’t strip hair so harshly and the shampoo helps to keep the hair from looking heavy. Win-win.

Of course, that’s not to say you need to go through this entire routine every single time you clean your strands. Hair masks are kind of like face masks, in that you can get by doing them about once a week. “Hair masks provide a surge of moisture and nutrients, so they are perfect for reviving hair—especially when it’s looking and feeling dry or generally lackluster,” says Tara Foley, beauty expert and founder of clean beauty shop Follain. The more you know.

Oh, and this is how to wash your hair like they do at the salon.  To keep those strands healthy, try these 10 supplements for thicker, fuller hair.