From The Nat­ur­al Haven Bloom’s series on Deep Con­di­tion­ing

For the past cou­ple of weeks we have been talk­ing deep con­di­tion­ing. Today is the turn of two fac­tors that are real­ly key name­ly tem­per­a­ture (should you use heat when con­di­tion­ing?)  and time (should you leave a con­di­tion­er on for hours?).

Now for the pur­pose of this post, I will again define a con­di­tion­er as a water based con­di­tion­er (deep, inten­sive, mask or rinse out). If you are using oil, this is com­plete­ly dif­fer­ent and its own rules apply.

So will heat and time affect con­di­tion­ing? The quick answer

Increased time and tem­per­a­ture do increase the amount of con­di­tion­er adsorbed to the sur­face of hair. The max­i­mum time is 20–30 min­utes and the max­i­mum tem­per­a­ture is around 35°C.

The long answer

I am being very gen­er­al in this post because the fact is that every sin­gle ingre­di­ent that can adsorb and/or pen­e­trate into hair (e.g sur­fac­tant or pro­tein) actu­al­ly has its own unique behav­iour when added to a con­di­tion­er. This is also affect­ed by oth­er ingre­di­ents in the con­di­tion­er.  How­ev­er there are com­mon sim­i­lar­i­ties in behav­iour and these are the ones I wish to empha­sise.

1.  Increas­ing the time you leave con­di­tion­er on hair allows more of it to adsorb with a max­i­mum adsorp­tion at 20- 30 min­utes.

The key ingre­di­ents that can stick to hair (sur­fac­tants, hydrol­ysed pro­tein, sil­i­cones, polyquats etc) will do so with­in sec­onds of apply­ing the con­di­tion­er. If left on hair for longer, the amount will in gen­er­al dou­ble with­in 10 min­utes. If left on for anoth­er 10–20 min­utes, the amount will increase by anoth­er 60–100% of the mark set at 10 min­utes.

How­ev­er after 30 min­utes from ini­tial appli­ca­tion, there are no more increas­es in con­di­tion­er adsorb­ing to hair. The rea­son for this is that the hair con­di­tion­er sim­ply has no more places on the hair where it can stick to.……all gaps which it can plug and all sur­faces where it can attach are occu­pied.

The gen­er­al graph that is obtained looks some­thing like this

The rela­tion­ship between con­di­tion­ing time and adsorp­tion

If you look at the 10 minute mark, you can see about 5% is on hair and at the 30 minute mark this increas­es to 10%. How­ev­er at 40, 50 or 60 min­utes there is no fur­ther increase, it just stays at 10%. Please do note that the num­bers  5% and 10% are NOT real mea­sure­ments. Adsorp­tion is usu­al­ly much low­er than this (even as low as 0.01%) but for ease of digest­ing the infor­ma­tion I picked sim­pler num­bers like 5 and 10.

2. Increas­ing the tem­per­a­ture of a con­di­tion­er to sur­face body tem­per­a­ture (around 35°C) increas­es adsorp­tion of a con­di­tion­er 

Tem­per­a­ture increas­es the adsorp­tion of con­di­tion­er such that slight­ly more can stick to the sur­face.  Gen­er­al­ly tests are not per­formed much high­er than 35–40°C in order to not burn the skin.  The graph looks some­thing like this

There are two main lines in the graph one in blue at 20°C and anoth­er in orange at 35°C. What you see is that the orange line is shift­ed just slight­ly about the blue one. This means when con­di­tion­er is heat­ed to 35°C, at 10 min­utes there is slight­ly more than 5% on hair and at 30 min­utes there is slight­ly more than 10%. There­fore tem­per­a­ture increas­es adsorp­tion. The rule how­ev­er remains the same in terms of no fur­ther con­di­tion­er stick­ing to the sur­face after 30  min­utes.

Oth­er influ­enc­ing fac­tors

1.  pH : The pH of your con­di­tion­er mat­ters. In gen­er­al pH between 6–7 work well to increase adsorp­tion to hair. Below and above this range, the behav­iour of the con­di­tion­er can become a lit­tle more errat­ic
2. Ingre­di­ent Quan­ti­ties: Con­di­tion­ers are dif­fer­ent and con­tain dif­fer­ent quan­ti­ties of ingre­di­ents. For exam­ple, a con­di­tion­er which con­tains 0.2% hydrol­ysed pro­tein will be able to leave about 20% more pro­tein on the sur­face of hair com­pared to one which has 0.1%.  The result is more dra­mat­ic for sur­fac­tants with a 0.2% con­di­tion­er able to adsorb 80% more to the sur­face than a con­di­tion­er with 0.1% sur­fac­tant. The thing is, man­u­fac­tur­ers will not tell you how much is on the jar, so you have to try the prod­uct and trust that your hair will tell you whether the prod­uct has too much or too lit­tle of the ingre­di­ent you are look­ing for.


J Soc Cos­met Chem, pp 259–273, 1992
J Soc Cos­met Chem, pp 351–359, 1991
J Soc Cos­met Chem, pp135-152, 1969

I will put up a sum­ma­ry post next week in com­bi­na­tion with your key ques­tions from the series. This is prob­a­bly one of the more com­plex posts that I have put up so if you do not under­stand any­thing here, feel free to shout!

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31 Comments on "Do Heat and Time Really Make Deep Conditioning More Effective?"

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I love this post I’ve always won­dered if keep­ing deep con­di­tion­er on for hours is actu­al­ly worth it espe­cial­ly when it starts to drip like mad.

Charday Morris

Do you have to use heat when deep con­di­tion­ing? I just put a cap on my head for 30 to and hour with­out heat


Heat caus­es the scales on the hair to raise up, which then allows your prod­uct to pen­e­trate the hair shaft bet­ter, and give the intend­ed results. I do use prod­ucts with­out exter­nal heat in a pinch how­ev­er. A plas­tic cap for 10–30 min­utes is bet­ter tnan noth­ing.


Great post.


I dis­agree. Time and con­sis­tent humid­i­ty make a dif­fer­ence in con­di­tion­ing the hair. When I con­di­tion my hair overnight it turns out alot shinier and feels soft­er than leav­ing on a con­di­tion­er for 30 min­utes hence min­i­miz­ing break­age. The hype is real. I also say humid­i­ty plays a major part because when I went under a steam­er ver­sus a dry­er with a con­di­tion­ing cap my hair was alot soft­er again and shinier.

Vanessa Carter
I’m not sure if you have heard of a woman named Tal­isha Berry, but I had a plea­sure of meet­ing her while at a con­fer­ence for work in Port­land. Tal­isha shared her book tips with me and also allowed me to sam­ple her new hair growth prod­uct which includes a blend of organ­ic essen­tial oils. I lie to to you not, my hair has grown 4 inch­es and is so healthy and that was just 3 months ago! My hair is coarse and very thick and I was suf­fer­ing from break­age. I would def­i­nite­ly rec­om­mend you ladies to check her… Read more »

Does the prod­uct come with a mon­ey-back guar­an­tee?


Wow this is so inter­est­ing. I’ll think about decreas­ing my deep con­di­tion­ing time, but I need to do more research first. Here is my favorite deep con­di­tion­er.


The heat caus­es the scales on the out­er lay­er of the shaft to open. That allows the prod­uct to pen­e­trate the shaft, not just stick to the out­er lay­er. The prod­uct has a bet­ter effect if it pen­e­trates the shaft.

Laurie A

At the end of the day just like prod­ucts and styles, it comes down to per­son­al pref­er­ence. The amount of time we keep in con­di­tion­er is based on the “feel” we want. Per­son­al­ly, when im gonna do curls i go for an hour, oth­er than that, its just the spec­i­fied 5–10 mins


I think body heat is enough to make the treat­ment be absorbed, I do this with some pro nat­u­rals argan oil and a show­er cap and my hair looks super shiny and smooth after­wards.


Body heat, which cer­tain­ly is enhanced by using a plas­tic cap, isa heat source, but the scales of the out­er lay­er may not open as much for max­i­mum prod­uct uptake. Still it does help, and I have done it many times. How­ev­er, being a woman with extreme­ly dry and brit­tle hair, I like max­i­mum effect!


I also think it depends on your hair if I leave con­di­tion­er in for too long my hair becomes limp and life­less and real­ly quite nasty. I find that 30 min­utes with a hot tow­el or in the steam room is quite enough. How­ev­er if I am in the sauna my hair can take longer peri­ods say an hour. I’m sure some­one knows the chem­istry behind this.


Right, it is pos­si­ble to over-con­di­tion. I had that mushy feel­ing because of over­con­di­tion­ing. Now I have cut back on the fre­quen­cy of con­di­tion­ing and I also make sure to also use a pro­tein prod­uct.
Every­thing in bal­ance!

The Natural Haven

You are total­ly right, the truth is many nat­u­rals actu­al­ly LIKE the feel­ing of over­con­di­tioned hair (extreme­ly soft, tends to hang a little/ be limp/ not hold a curl). 

More often peo­ple who have hair that can form ringlets/spirals will tend not to like over­con­di­tioned hair as it pre­vents the curls for­ma­tion and makes hair feel mushy. If you are in this group, you may find that as lit­tle as a quick comb through with the con­di­tion­er is enough for you.

Jo Somebody
Tbh, I leave con­di­tion­ers in longer usu­al­ly due to lazi­ness. 30 min­utes is too long to stay in a ‘wet’ state (e.g. in the show­er) and if I’ve come out of the show­er, dried and dressed myself (or put on PJs), I am loathed to wet my head again. Also, night­ly deep con­di­tion­ing would mean rins­ing it off and going to bed with wet hair. DC’ing overnight and rins­ing out in my morn­ing show­er works well for me! It then has all day (and anoth­er night if need­ed) to dry and stretch. Two addi­tion­al points are that my hair is… Read more »

+1 I’m an overnight girl, at least until I fig­ure out how to do a WNG at night. Napptural85’s win­ter wash and go only worked on 10% of my hair, the rest was an unde­fined mess.


Does it also depend on how porous your hair is? I have high poros­i­ty hair, so I’m sure five min­utes is enough for me. But for low poros­i­ty nat­u­rals, maybe the extra hours are ben­e­fi­cial?

Ugonna Wosu

you know what? All I can tell you is how it works for me. In my expe­ri­ence? YES, they absolute­ly make a dif­fer­ence. Hav­ing the con­di­tion­er on for like 5 min­utes wouldn’t do any­thing that dras­tic to my hair, so the next time a sci­en­tist says it makes no dif­fer­ence, he bet­ter show me a demon­stra­tion on his OWN hair while try­ing to tell me its mak­ing no dif­fer­ence, lol.

The Natural Haven

I have already done a post on why hair care needs to be tai­lored to your per­son­al expe­ri­ence. Sci­ence can only give you insight into what is hap­pen­ing at a mol­e­c­u­lar lev­el.

By the way, I am a female sci­en­tist. I do won­der why cer­tain pro­fes­sions are almost by default classed by male gen­der ( doc­tor, sci­en­tist, pilot).


Yes. I know what the sci­ence says, but when I’m feel­ing out of it and not in the mood to do my hair, I’ll throw in some con­di­tion­er and keep it in a bun for one or two days. and when I take my hair down and rinse the con­di­tion­er out, it feels aMAAAAAAAAAAAAAZ­ING­LY soft! Soft­er than it does when I just have it in for 1/2 hour. 

There is some­thing to this…I think sci­ence just hasn’t fig­ured it out yet.

The Natural Haven

Actu­al­ly the series is not fin­ished. I will give you a heads up, the rea­son why you hair feels so soft is pret­ty much the same way your nails get soft­er when you soak them in water for a long time. It is relat­ed to the ker­atin con­for­ma­tion (ker­atin being the pro­tein in hair and nails). 

For nails the truth is the more often you soak them, the weak­er they even­tu­al­ly become (have you ever tried wash­ing dish­es by hand every­day for a week and com­pare how your nails feel com­pared to a week of not doing that?)

I was going to say some­thing like that, but with­out the sci­ence:). I’ve also learned about the down­fall of over-conditioned/moisturized hair. I do tend to leave my pre-poo (Vati­ka oil mixed with Aubrey GPB, Hon­ey­suck­le Rose or both) in overnight for the coconut oil ben­e­fits and because the study behind that was with an overnight treat­ment. But, I only leave DCs on overnight any­more out of pure exhaus­tion and/or lazi­ness as I know that too much of a good thing can become a bad one. I’ve learned that extra soft hair actu­al­ly isn’t good and a lit­tle “body” is an… Read more »

Oh, and I also use a heat tur­ban as I do find that real­ly ben­e­fits my hair.

Pecanprincess southernstyle
Pecanprincess southernstyle

Dit­to skit­tle!!!

Basi­cal­ly, it seems as though the effec­tive­ness of a deep con­di­tion­er is based on the actu­al prop­er­ties of the con­di­tion­er and how long it is left on the hair until sat­u­ra­tion point is reached. Heat facil­i­tates the adsorp­tion, but once sat­u­ra­tion point is reached (30 min), no oth­er ben­e­fit is had by heat. Some ingre­di­ents are ADsorbed (attach to the sur­face of the cuti­cle) more read­i­ly than oth­ers. Prod­ucts with pH in the same range as hair itself, being the most eas­i­ly ADsorbed. Very few ingre­di­ents are actu­al­ly ABsorbed (tak­en into the cuti­cle). Mois­tur­iz­ing oils like jojo­ba, coconut and argan oils… Read more »
The Natural Haven

lol I am so going to adapt your way of writ­ing aDsorb. It is a real­ly impor­tant con­cept that I cov­ered in the first part of the series on my blog.


Very good blog post. I haven’t been fol­low­ing the deep con­di­tion­ing series, but after read­ing sev­er­al of JC’s posts as well as that of anoth­er cos­met­ic sci­en­tist in the nat­ur­al hair com­mu­ni­ty, I’ve made sure to only leave on deep con­di­tion­ers as long as the con­tain­er says. I also don’t add heat unless it says so. Fol­low­ing the direc­tions is key to achiev­ing opti­mal hair health. Thank you for this post!


I love this arti­cle because I am kind of a nerd, and I love the sci­ence of things. ;)

I have heard of nat­u­rals doing 8 hour con­di­tion­ing treat­ments so it’s good to find out that 30 min­utes is real­ly the max­i­mum absorp­tion time. When I deep con­di­tion, I typ­i­cal­ly sit under a hair dry­er for 15–20 min­utes with good results.

Ugonna Wosu

10 min­utes and up is fine. I think 8 hours is unnec­es­sary, but 1–2 hours cer­tain­ly works for me. :)


Yeah, I might do 1–2 hours if I had the time.…it is nice to take that time to com­plete­ly pam­per your hair!