This Science Sunday, we’ll talk about what conditioners are actually doing for your hair. But first, let’s start with the basics.

what is conditioner?

Conditioners—both rinse-out and leave in—typically consist of a mixture of emollients, waxes, and polymers that coat the hair, ultimately making it more manageable. While almost every conditioner claims to help moisturize or hydrate hair, this benefit comes from the softening and smoothing ingredients that offset the look + feel of unhealthy hair. So what does that mean for you? Maybe post-conditioner your hair feels great, but the deeper damage is still there, right below the surface. We like to think of conditioner like another C word in the beauty space: concealer. In true form, conditioner is less like a hydration boost for strands and more like a temporary patch-job to cover up signs of unhealthy hair like frizz, dryness + dullness.

So let’s talk cosmetic chemistry.

Yes, this again.

Hair is naturally negatively charged, even more so when damage is involved, resulting in tangles and frizz. Instead of eliminating or repairing this negative charge, most conditioner formulas use permanently positive charged cationics or “quats” to remove hair’s extra charge and create a smooth look.

Another smoothing benefit comes from emollients, which typically sit on the surface of hair to soften, combat moisture-related frizzing, and add slip for easier combing and added shine. By weighing hair down, emollients stick strands together so light reflects more evenly, and appears shiny and healthy. One of the many clever tricks used by cosmetic chemistry to make hair appear healthy, rather than repairing it.

Unfortunately, hair looking good does not necessarily translate into hair being healthy.

what does conditioner actually do?

Traditional conditioning products patch up and hydrate the outer layer of hair to make it more manageable by looking and/or feeling nicer. The positive? This can help diminish new damage (think slippery conditioners for minimizing friction when detangling)…but do nothing to repair the existing damage.

The biggest bummer? The surface-level benefits you do get don’t last for long, and often make hair needier with every use. Since these smoothing + softening ingredients are largely washed out during your next shampoo, you need to continually reapply to get those benefits at all. But, if your hair isn’t properly cleansed or is washed with hard water, conditioner ingredients can cause build-up and weigh hair down.

the needy hair cycle

If you caught our pH blog, you know the best pH for hair is slightly acidic, around 5. Unfortunately, conditioners are rarely formulated for pH optimization, very few even list their pH, so your conditioner may be disturbing your scalp’s self-regulating system, causing further irritation, which people tend to cover with… you guessed it, even more conditioner.

This is perpetuating a vicious cycle of disrupting your hair + scalp natural balance, stressing your strands, and making hair needier for more product, energy, and time spent taming it. This is all contrary to what conditioner is meant to do, so what gives? By masking damage instead of building a healthy hair base in the first place, big beauty gets you to buy more than you need to. Yikes.

So, how do you stop this vicious cycle?

healthy hair needs less

A simple hair care routine of shampoo + skipping conditioner can help the nourishing oils and other styling products you apply on top penetrate better (exactly why we suggest a clarifying shampoo before using K18).

In short, conditioner coats your hair to make it more manageable—but this does not translate to hair “health” in terms of contributing to strength, so it’s important to build your routine around core strength in addition to those moments you need a little extra cover-up.