Deep Conditioning, Part I

Note: This series applies to Protein Deep Treatments too!

This is the first of a two part post. Today's post is about how deep conditioners work and who needs one. Part two is about how to use a deep conditioner to get the most out of it.

Deep conditioning on wet hair is applying conditioner to freshly washed hair to leave on for a few minutes (or longer). You could put a deep conditioning treatment on unwashed hair, but because you'll get the best result from having the conditioning treatment in complete, unfettered contact with your hairs. It's better to deep condition clean hair and get rid of the dust and dirt and pet hair, twigs, leaves and other junk first.

©Science-y Hair Blog 2014

A pH level of 7 (or at least around 7 and above 5) has been shown in laboratory testing to promote the most adherence of conditioner to your hair. It is best to stay between pH 6 and 7.  Most store-bought conditioners will already be in this range. If you start adding acidic or alkaline ingredients, get some pH test strips and test the pH of what you're adding. If you want to maximize your hair's uptake of conditioner, you want control of the pH.©Science-y Hair Blog 2014

Normally (non-wet) hair has a net negative charge - more negative charges than positive charges. Especially normal porosity and porous hair. For most of us, hair below ear or chin length is normal porosity. If you color or highlight your hair, brush it often, spend a lot of time in the sun or swimming pools, or it is very long, the ends are likely to be porous.©Science-y Hair Blog 2014

The more porous the hair, the more easily dehydrated it is. And the more negative charges it has. Porous hair also has gaps in the cuticle "covering" that are temporarily patched in by this adhering of conditioner to negatively charged surfaces.

©Science-y Hair Blog 2014

Dry (not wet) hair has more negative charges 
thanpositive charges.

What's the deal with negative charges?

Conditioning ingredients have positive charges that allow them to interact with negatively charged hair. Like magnets, positive is attracted to negative. The conditioning ingredients adhere (technically accurate term: adsorb) to your hair temporarily and do not rinse off. This leaves a layer of conditioning behind to help reduce friction in your hair and add softness and flexibility.©Science-y Hair Blog 2014

What sorts of ingredients have positive charges?

Hydrolyzed proteins - slightly positively charged

Stearamidopropyl Dimethylamine

Quaternium-87

Behentrimonium Methosulfate

Behentrimonium Chloride

Dicetyldimonium Chloride

Distearyldimonium Chloride

Polyquaternium 55

Guar Hydroxypropyltrimonium Chloride 

Polyquaternium-44 

Cetrimonium Bromide

Cetrimonium Chloride

Palmitamidopropyltrimonium Chloride

Laurdimonium hydroxypropyl hydrolyzed wheat or soy or keratin protein

Polyquaternium-4

Polyquaternium-10

Cationic conditioner (pink + symbols) adhering (adsorbing) to the negative charges on hair at
the proper pH at left. Conditioner not adhering to hair at a too-low pH at right.

But wait! There's more to conditioning than positive and negative charges: When lipids (oily ingredients) are present in a conditioner formula (or when you add them), you get even more conditioning goodness adhering to your hair - more cationic conditioning and more softness and flexibility from the lipid. It's an interesting mutual enhancement of conditioning ingredients for an even better end result. The presence of lipids in a formula makes it a better deep conditioner. Lipids themselves are great hair softeners and lubricants.

©Science-y Hair Blog 2014

In most conditioners, the lipid is already present in the form of cetyl alcohol or cetaryl alcohol because this ingredient makes a nice creamy, thick conditioner with a soft after-feel. But other oils do the trick also, including plant oils or butters you might add to a conditioner. Adding extra oil to a conditioner really does turn it into a deep conditioner! Sounds like a money-saving tip to me. 

What else is good in a deep conditioner?

If you have porous hair - hair that always seems to soak up oil and conditioner, your hair will probably appreciate hair-penetrating oils in a deep conditioning treatment; coconut oil, sunflower oil, possibly grapeseed oil to help your hair avoid excessive swelling in water. Cetrimonium bromide and probably Cetrimonium chloride can penetrate the hair shaft slightly for a "deeper" conditioning effect, and so can panthenol and amino acids from hydrolyzed proteins.

If you have tangle-prone hair or tightly curled or coiled hair, just about any oil is a good addition because you need lots of lubrication to keep your hairs sliding past each other. Butters like shea butter can be good in some people's hair and cause build up or friction in other people's hair. Warm them so they melt and mix them thoroughly into your other ingredients.

Almost any hair can benefit from moisture-hugging humectants - warmed honey, aloe vera, glycerin (maybe, it works better in humid weather), look for Hydroxypropyltrimonium honey, Sodium PCA, panthenol, Hyaluronic acid.©Science-y Hair Blog 2014

Proteins: If your hair handles protein well (see this post about protein), it can be a good ingredient in or addition to a deep treatment. Hydrolyzed protein helps your hair stay hydrated. Protein in products slows moisture loss from your hair. Look for products containing hydrolyzed proteins, amino acids and peptides. Proteins carry a weak cationic charge, so they play by the same rules for heat and length of time that are coming in Part II.  

Salt? When salt is added to conditioner, it decreases adsorption (ahderance) of conditioner to hair. Instead of conditioner adsorbing to your hair, the salt does instead because it has more "charge." The salt blocks the conditioner. Salt may feel slippery and humectant-y once in a great while, but if used often it creates friction in hair. Salt attracts water strongly (creates an osmotic gradient and will pull water to itself from anything else that has water). If salt is in your water-based conditioner on wet hair, there's plenty of water for the salt. But left on your hair, the salt molecules will pull water from your hair. That's how it can act as a humectant in humid air, but in dry air - that salt will pull water right out of your hair. Have you ever salted eggplant to pull out the water before cooking it? Or salted cucumbers or cabbage before making pickles or sauerkraut? Salt pulls water to itself. Better not salt your hair too often.

Whose hair needs deep conditioning? Not everybody's. Lower porosity, un-bleached or un-dyed hair cannot adsorb much conditioner and it's more likely to accumulate build-up. 

I don't lump hair into categories readily because everybody's hair is so much alike - and so different! I think about hair at the microscopic level, at the "individual hair strand" level, and also about the forces acting on hair like whether it is straight or curly or kinking because force on hair is distributed very differently on and within tightly curled hair relative to more loosely curled or straight hair. 

©Science-y Hair Blog 2014

So whose hair needs deep conditioning?

• Bleached hair (highlights, "lightener," hair dyed with permanent-color or demi-permanent color)
• Very long hair that feels dry and rough on the ends
• Hair that tangles easily (it may be straight, wavy, curly or tightly coiled)
• Hair that is experiencing a lot of breakage (at the ends, mid-shaft splits, or anywhere else)
• Hair that is acting frizzy or poofy or flyaway and needs weight and/or slip to pull itself together
• Hair that feels constantly dry
• Hair that has spent many hours in the full summer sun, in swimming pools, in salt water, in dry wind
• Hair that feels dry, rough, inflexible and dull
• Hair frequently straightened or curled with high-heat styling tools (high heat blow dryer, curling iron or straightening irons)
• Hair that has been chemically straightened or curled

In Part II: How to use a deep conditioner to get the most benefit, how to deep condition low porosity hair - and more.

Journal of Cosmetic Science Vol. 4 No. 3, 259-273 September/October 1992

Assessment of the substantivity of cationic quaternary compounds to hair by potentiometric titration using the surfactant electrode. NGHI VAN NGUYEN, DAVID W. CANNELL, ROGER A. MATHEWS, and HANS H. Y. OEI

Journal of the Society of Cosmetic Chemistry Vol. 4 No. 5, p. 85-94 1994

Adsorption to keratin surfaces A: continuum between a charge-driven and a hydrophobically driven process.

C. R. ROBBINS, C. REICH, and A. PATEL

Journal of Cosmetic Science, 60, 85–95 March/April 2009

The effects of lipid penetration and removal from subsurface microcavities and cracks at the human cuticle sheath

MANUEL GAMEZ-GARCIA

Chemical and Physical Behavior of Human Hair 

Robbins, 1994. 3^rd Ed. Springer-Verlag, New York