Glycerin and Humidity

Cindy asks a winter inspired question from frigid Wisconsin where humectants are making the winter of 2014-2015 even more frustrating. You need to know that here in the Midwestern U.S.A. (like Wisconsin), winter tends to be very cold and very dry. So even when we see the outdoor humidity is, say, 50%, if the temperature is 10°F (-12°C), the air is still extremely dry and the dewpoint - that temperature indicating how much water the air could hold if it was fully saturated - could be below 0°F. That is desert-dry air.

I zero in on glycerin because it can be a curly or wavy-haired person's dry-air nemesis. But I didn't leave many out, so read on. "Humectant" is a very broad category including salts, glycerin, plant gels like aloe vera or flax gel, algae extracts, hyaluronic acid, hydrolyzed proteins, sodium PCA, lactic acid, urea, witch hazel (without alcohol) and other ingredients that attract water. Not all humectants are "created" equal - different humectants behave differently in hair. I think when people complain about humectants, they are having the most trouble with simple humectants like: glycerin, propylene glycol, sorbitol.

Humectants attract water to themselves. Humectants like glycerin are great at grabbing water vapor out of the air. When you have a hair gel with glycerin in it, when there is ample water in the air (humidity) - the air is going to be hydrating the glycerin in the product, which is going to help your hair stay hydrated. Well-hydrated hair has more bounce and definition. A second benefit of glycerin in products (when there is ample water vapor in the air) is that glycerin keeps hold-providing ingredients that would otherwise create a brittle, candy-like finish from feeling brittle and candy-like. Glycerin (and sorbitol and propylene glycol) take water vapor from the air to hydrate the dry gel in your hair and keep it more flexible.

When there isn't enough water vapor in the air (low humidity and/or low dewpoints), the gel loses that benefit from the glycerin and the gel becomes more brittle, creates friction and that means hair that feels dry and crusty and looks dull.

Whether humectants actually dehydrate the hair - pull water from the hair is not well-studied. And it is an "it all depends" sort of question. It is based on a reasonable hypothesis; that if glycerin attracts water from the air, when the air is drier than your hair, water will move from your hair to the glycerin. For that matter, when the air is less humid than the inside of your hair - the water will tend to move from your hair to the air around it - glycerin or not. So does glycerin create a stronger "pull" (water gradient) than dry air alone? It probably does exert a stronger pull on the water in your hair than dry air alone. But not all humectants do that. Think of glycerin like brown sugar. In humid air, a bag or tin of brown sugar absorbs moisture and forms clumps. But it dries out quickly too and the clumps become hard as a result.

Don't discount the effect of that dehydrated gel sitting on your hair because 1) glycerin can't pull enough water out of your hair to keep a gel from getting brittle and 2) brittle gel creates friction - that means rough, tacky hair that frizzes when it contacts other hairs and objects and snags at cuticle edges. A crusty, dehydrated product in your hair is bad news for how your hair looks and feels.

Mitigating circumstances

If you used oil or leave-in conditioner under a glycerin-containing product, that layer of emollients would slow down water loss from hair. If there are other humectants that are not a ready to give up their water as glycerin in the same product, the effect might be reduced. Oils and conditioners act as "occlusives" - the layer of oil or leave-in conditioner is not water-soluble and that helps slow the movement of water in and out of hair.

Why glycerin, why must you be so fickle?

To get to the heart of why glycerin can be a problem ingredient for some people in some weather, one big issue is the size of the molecule. The smaller the molecule, the less water it can bind and hang on to when exposed to very dry air. Glycerin, sorbitol and propylene glycol are "sugar alcohols" - not alcohol like the kind used in hairspray. They are small molecules. There are not a lot of places on the molecule to bind water. Think of glycerin as a "simple sugar" as you would think of candy. Sure, glycerin and sorbitol and propylene glycol aggressively pull water to themselves, but they also lose it fairly easily. Emollients (oils and conditioners) can slow that down, but not stop it. So when the air is very dry - glycerin is a much less effective ingredient. Glycerin is a fair-weather friend. When the humidity is just right, glycerin can help your hair look and feel great. When the weather gets too dry, glycerin can't pull enough water to itself and it loses it's effectiveness. When the air is very humid and glycerin pulls lots and lots of water in - poof - your hair loses definition. 

Glycerin is a small molecule and not
very complex.

Formulation can be a problem

Often, a problem with a glycerin-containing product is that it uses only glycerin for a humectant and "flexibilizer" and does't use any emollients or film-forming humectants at all. Well-balanced products avoid this pitfall. Different humectants have different actions and a combination of different size and molecular weight humectants might be okay for a person who finds that just glycerin and no emollients or film-formers is a mess.

Is it just me?

There are people who live in climates that are dry year-round and use glycerin with no problems at all. And there are people who can only use glycerin when the humidity is "just right." There is no simple rule to determine how your hair will respond because it's not just a porosity issue. It's an issue of climate and weather, what other products you use in your hair, how sensitive your hair is to increased friction, how often you go outdoors. Trial and error. As usual. 

Is there a winter-proof (dry-weather-proof) humectant?

A great big molecule like the complex carbohydrates in flax seed gel or hydrolyzed proteins behave differently in hair than glycerin. These ingredients don't rely heavily on water vapor to work well. They don't have aggressive water-grabbing force. They're more subtle. There are many places to bind water in these molecules. Not only that, but they also form clear, flexible films over your hair. Water-hugging films that tend to slow water loss from the hair. If these large, moisture-retaining humectants which I call "film-forming humectants" are combined with oils or conditioning ingredients in a styling product, the humectants and oils and/or conditioning ingredients combine to actively attract and hold water and slow water loss, providing longer-lasting hydration and lubrication. The link in the previous sentence takes you to a list of film-forming humectants.

One of the many complex carbohydrates
in flax and other plant gels. It is a larger
molecule and more complex, capable of
forming water-hugging films.

Hair that cannot tolerate simple humectants like glycerin or propylene glycol may still do well with film-forming humectants in styling products. What we want from styling products is extremely personal. If you are looking for hold or definition, these are some styling products which may work:

AG Weightless Volumizer

AG Mousse Gel

AG Re:Coil

Aussie Real Volume Mousse

Aussie Instant Freeze Gel

Camille Rose Aloe Whipped Butter Gel

Curl Junkie Curl Queen

Curl Junkie Pattern Pusha

Biosilk Rock Hard Gelle

Darcy's Botanicals Curling Cream Gel

DevaCurl Set Up and Above

Goddess Curls Gel

Herbal Essences Totally Twisted Curl Scrunching Gel

Herbal Essences Set Me Up Gel

Herbal Essences Naked Volumizing Souffle

Jessicurl Confident Coils Styling Solution

LA Looks Nutra Curl Moisturizing Gel

Salon Care Aloe Vera Styling Gel

Pantene Pro-V Stylers Max Hold or Strong Hold Gel

For products that are based on film-forming humectants, including many natural and plant-based gels, go to  this page on this blog and scroll down to the list of products including film-forming humectants. Some contain glycerin - check the ingredient lists. Most are light to medium hold and can be topped with a gel with stronger hold, like Biosilk Rock Hard Gelee (from the above list) if necessary.

Why are plant-based, film-forming humectants less "fickle?" Stuff about plants.

Flax seed is an example. The gel comes from water contacting the seed. Seeds do this so that when they are in the soil and the soil is moist, the seed can attract water, form that gel which assures the seed will stay moist enough to sprout. If a seed gets wet, begins to sprout and then dries out, it dies. So this is a brilliant adaptive strategy to assure seeds sprout to create new plants and more seeds.

With aloe vera, that is a desert plant. It has thick, leathery leaves with spines on them to discourage animals from eating the juicy leaves and to prevent water loss. The gel in the inner leaf does not dry out quickly, a good strategy for a desert plant.

Why Does White (or gray, light blonde, highlighted) Hair Turn Yellow: And what to do about it

Science-y Hair Blog © 2011 by  Wendy M.S. is licensed under CC BY-NC-ND 4.0 

This applies to white or gray, highlighted and blonde or light brown hair that may tend to become brassy or develop an unnatural color tint - yellow, red, orange or greenish.

White hair has no pigment. Although sometimes that's not entirely the case as a hair turns white. And sometimes there's a dark medulla to add color. The lighter your hair overall, the more likely discoloration from any source will show.

What causes yellowing of light-colored hair?

• Water chemistry: Hardness or natural minerals, chemicals used for water treatment, seasonal water chemistry changes all impact whether or not your water discolors your hair. For example, if your water source comes from lakes and rivers, it varies greatly (within drinkable limits) with changing seasons and the treatment needed to make the water safe to drink. Some water is high in iron which can give hair an orange, red or yellow cast. Other things in water (metals) can cause green or brown discoloration. Alkaline water can be also problematic (hard water that feels slippery). It's not just minerals that vary, it's nitrates and nitrites, the amount of chlorination required, use of chlorine vs. chloramines for disinfection and whatever your water picks up from pipes on the way to you. 
• Hair products. Some oils and emollients, preservatives, and colorings can leave a yellowish cast on hair.
• Scalp oils. Sometimes you own sebum can give your hair a yellowish cast. And your own sebum can vary with seasons - sweat, heat or cold, activity level, microbial activity on your scalp. Natural sebum is a good thing. Don't worry about this one. But if you have oily scalp and you are not forcing it to produce lots of oil by over-washing it, wash it regularly - just don't dry it out. If you wear a hat often - wash the hat regularly or put in a hat band or liner that you can remove and wash. Also remember to wash your comb or brush - any tool that is in contact with your hair every 2-3 weeks in water with some diluted shampoo or hand cleanser to remove any "old" oils that might deposit on your hair.
• Smoke, pollution. Your hair can pick up these things. Especially close-up smoke like that from smoking cigarettes.
• Swimming pools and ocean water. Minerals in pool fungicides can cause a greenish or yellow tint, chlorine can increase hair porosity. Salt water dehydrates hair and causes porosity-increasing friction.
• Sunlight: UV light tends to make hair become more porous and it may also induce yellowing in some hair.
• Chemical processes: Perms, relaxing can make hair more porous so it is more easily discolored.
• High-heat styling. Heat from hair dryers on the "high" setting or much higher heat from curling irons or straightening irons tends to make hair more porous so it is more easily discolored. 

What to do?

1) Purple shampoos or conditioners (or additives) - usually made for grey, blonde or silver hair. Purple is meant to cancel out the yellow shade - to deposit a tiny bit of purple to trick your eyes into not seeing the yellow. A purple additive such as "Ardell Red-Gold Corrector" is a commercial product which can be added to shampoo, hair gel or leave-in conditioner so that it is a light shade of purple if you prefer not to use an unfamiliar product.

• Kevin Murphy Blonde Angel Wash
• Overtone Color Conditioners (purple and lavender shades)
• Clairol Shimmer Lights Shampoo
• One N Only Ultra Shiny Silver Shampoo
• Fudge Clean Blonde Toning Shampoo (and conditioner)

2) Bluing. Mix a few drops of liquid laundry bluing into shampoo or conditioner for a fairly vibrant blue - or just a little into a leave-in conditioner or hair gel so it is "sky blue." This color of blue is very effective at canceling out yellow shades in white hair and also in toning down brassiness. It especially enhances cool shades of brunette and dark brown hair and can give blonde and light brown hair an ash (cool) tone. If purple doesn't help - blue (bluing) may work better.

1 and 2: a) Use food coloring instead. You can use a few drops of blue food coloring in shampoo or conditioner, or blue + red to create purple. If this mixture, or a purple shampoo almost works, but you still have some reddish shade appearing, add the same number of drops of green food coloring to the mixture (example: 1-2 drops each of blue, red, and green). Have a mirror handy. If you over-did the color additives, wash your hair a second time.

3) If minerals or metals (copper, iron for example) in water are discoloring your hair, try a distilled water wash. Warm some distilled water and use it for your entire wash and rinse. This can help diagnose whether water chemistry is a problem for your hair. If you notice a benefit from doing this, you might try combining it with one of the suggestions from #4 or #5 below to remove minerals from the hair, or with a purple shampoo or a bluing-added product from #1 or #2.

4) Hard water shampoos and treatments (commercial). Ion Hard Water shampoo, Ion Crystal Clarifying Treatment, Malibu Wellness Hard Water Weekly Demineralizer or Malibu Wellness C Blondes Weekly Brightener. These treatments can remove hard water minerals (calcium, magnesium) and other problem minerals from your hair. But if you have more white hairs than colored hairs or you have very light blonde hair or light highlights, you must do a test section first to be sure you will not get discoloration from the treatment.  These treatments combine mineral chelators such as EDTA or citric acid with mineral dissolvers and detergents to remove product build-up. Hard water can exacerbate product build-up.

5) Lemon juice treatment (Do It Yourself). This is shampoo-free. It may help remove mineral deposits and it may brighten blonde and light brown shades. Mix equal parts lemon juice (strain out any pieces of pulp) and distilled water. Apply this to your hair (put it in a squeeze-top bottle for easier application). Work it in well and cover your hair with a shower cap, treatment cap or wrap your hair in plastic. Leave this in your hair with some heat for 3-5 minutes, then rinse well and follow with cleanser/shampoo and conditioner.

The pH of this treatment is very low, so you may want to do a test-strand first to assure it is not too drying for your hair. The combination of citric and ascorbic acids help dissolve and trap (chelate) minerals and remove them from your hair. 

You can make mock lemon juice with 1.5% each citric acid and ascorbic acid in distilled water. This will also have a very low pH and need to be used on a test-strand to make sure it does not dry your hair.

6) If you notice yellowing after adding a new product, the product may be the problem. Discontinue use of the product for a while. If it is more than one product causing the problem, scan the ingredients of the offending products for ingredients they have in common. Those ingredients may be potential offenders. Oils, some preservatives, herbal ingredients and colorings can discolor hair, for example.

7) If you began using oils in your hair, or if you have been sweating more than usual - you may need to shampoo your hair more thoroughly. You may find that some plant oils cause yellowing and others don't. Or some parts of your hair may be more inclined to yellow than others.

8) Treat any scalp disease you may have (seborrheic dermatitis, for example) so the oils on your scalp have the right composition and are not over-produced. You may want to avoid tar shampoos (unless that is the only thing that works) because they can cause discoloration.

9) Manage porosity in your hair by using conditioners, protein as your hair tolerates it, handle your hair gently (don't brush vigorously, don't rub and scrub it with a towel - just blot and squeeze dry), use oil pre-wash treatments to prevent "waterlogging." See this post for more about managing porosity. 

10) Wear a hat, scarf of "UV buff" in the sun or use a UV protectant in hair products such as Cinnamidopropyltrimonium chloride, Quaternium-95 and Propanediol (they need to be together),  Polysilicone-15 or Benzophone-4.

• Cinnamidopropyltrimonium chloride has been demonstrated in lab tests to prevent yellowing and increased brittleness in white hairs exposed to UV light (Gao and Bedell, Journal of Cosmetic Science, 2011. Volume 52, p.103-118)

11) For swimmers, use one of the mineral-removing treatments from #4 and #6 occasionally. If your pool allows, apply a little coconut oil or conditioner to your dry hair and wear a swim cap. The oil or conditioner protects the hair from pool water and the swim cap doesn't allow new water to constantly flow past and through your hair.

12) Other commercial products: 

• Manic Panic "Virgin Snow" is a conditioning "white hair toner" (it's purple in the bottle) with no peroxide that is left on the hair for 15-30 minutes to correct discoloration. 
• L'Oreal Colorist Secrets 'Brass Banisher" is a product that does contain peroxide for removing unwanted brassiness (red and yellow colors). If all else fails...

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Hair Porosity: The Float Test Part Two

Science-y Hair Blog © 2011 by  Wendy M.S. is licensed under CC BY-NC-ND 4.0 

It's time to examine the float test for hair porosity more fully. I began looking into how the float test could give you an inaccurate result in the previous post. Elsewhere on this blog I have mentioned that this test is not very accurate. This post will show you why. To make the test more accurate, see the tips at the end of the post
© Science-y Hair Blog 2

The idea behind the float test follows this line of thinking: If hair is porous, it takes on more water than if it is not porous. Therefore, porous hair might sink because it takes on water and becomes heavy. That is - the weight of the water the hair is absorbing overwhelms the power of surface tension (between water molecules) that keeps the hair suspended on top of the water.

And in a sense this is not wrong but it is incomplete. But there are too many other variables in play to make this an accurate assessment of how porous your hair is by simply grabbing some hair and dropping it in a glass. Your experiment needs to be designed with far more care than you might think to get anything close to an accurate result. Given time and enough dunking - all hair will sink in water and stay sunk.© Science-y Hair Blog 2015

I used some hairs which are low porosity, porous, kinking and porous and mixed porosity (lower near the roots, porous at the ends). I tested the hairs when clean (no products), with conditioner added, with coconut oil added and with hair gel added (homemade flaxseed gel) because these additions can change the floating behavior of hair.© Science-y Hair Blog 2015

In most cases I put some hair on the water's surface and also dunked another of the same hair because some people dunk their hair (push it under the water) for the float test and it tends to give a different result, at least at first. Captions are below each chart. Click photos that follow to enlarge.© Science-y Hair Blog 2015

Time	Untreated	Oil (All dunked)	Conditioner	Hair gel
Start	Floating, Dunked: Sinking	Sinks	Floating, Dunked: Sinking	Floating, Dunked: Sinking
5 minutes	Floating, Dunked: Sinking	Floating	No change	Floating, Dunked: Partly floating
10 minutes	Floating, Dunked: Sinking	Floating	Nearly all floating, dunked and un-dunked	Partly floating, dunked and un-dunked

Porous, coily/curly (Type 4) hair which has been lightened (highlighted). When untreated, it did partly sink over time. But at least half of the hair was on the surface. With oil, it initially sank when dunked (all hairs were dunked in this case), but then floated as the coconut oil repelled water. With conditioner, the un-dunked hair floated until the end of the test when it was partly sinking but the dunked hair sank initially, then floated as the weight and specific gravity of the hair vs. water and the waterproofing of conditioner got the better of it. Hair gel in this case was similar to un-treated hair - though hair gel can make hair more water-attracting.

Time	Untreated	Oil	Conditioner	Hair gel
Start	Floating	Floating, Dunked: Floating	Floating, Dunked: Sinking	Floating, Dunked: Sinking
5 minutes	Floating	Floating, Dunked: Floating	Partly floating, dunked and un-dunked	Partly floating, dunked and un-dunked
10 minutes	Floating	Same as at 5 minutes.	Same as at 5 minutes.	Same as at 5 minutes

Mixed porosity hair (lower porosity at roots, porous at ends), loose curls with kinking. The untreated hairs all floated (none were dunked). The oiled hairs also floated. With conditioner, the wet-ability of the conditioner encouraged sinking, whether the hair was dunked or not. With hair gel, the wet-ability of the hair gel encouraged sinking.

Time	Untreated	Oil	Conditioner	Hair gel
Start	Floating, Dunked: Partly sinking	Floating, Dunked: Floating	Floating, Dunked: sinking	Floating, Dunked: sinking
5 minutes	Floating, Dunked: Partly sinking	Floating, Dunked: Floating	Partly floating, dunked and un-dunked	Floating, Dunked: Partly floating
10 minutes	Floating, Dunked: Partly sinking	Floating, Dunked: Floating	Floating, Dunked: Partly floating	Floating, Dunked: Partly floating

Low Porosity, coily (Type 4), kinking hair. This hair floated as expected when untreated and simply placed on top of the water - but it seems the shape of the hair pulled it down when dunked. It floated when oiled both dunked and un-dunked. Conditioner's wet-ability encouraged some sinking with time, as did hair gel.

Time	Untreated	Oil (All dunked)	Conditioner	Hair gel
Start	Floating, Dunked: Partly floating	Floating	Floating, Dunked: sinking	Floating, Dunked: sinking
5 minutes	Same as at start	Floating	Floating, Dunked: partly floating	Floating, Dunked: partly floating
10 minutes	Same as at 5 minutes	Floating	Floating, Dunked: mostly sinking	Floating, Dunked: partly floating

Porous, wavy hair, which has been lightened (highlighted).

The porosity of this hair encourages sinking when the hair was dunked. The hairs floated when oiled but conditioner's and hair gel's wet-ability encouraged sinking in the dunked hairs.

Comments:

Do you see any trends? © Science-y Hair Blog 2015

• Porous hair does indeed tend to sink somewhat reliably: 1) if the hair is clean - no products 2) over time, 3) if the hair is dunked under water first.
• Conditioner and hair gel on hair tend to encourage hair to sink if it has been dunked under water first - but it may float after a little while. 
• The curl of hair or lack of curl or for that matter if you have hairs touching other hairs, may change the result, especially if you dunk hairs.
• Oiled hair tends to float - especially coconut oil.
• Dunked hairs vs. hair placed on the surface may produce a different result. And that result may change if you leave the hair for a few minutes. As you can see from the charts - whether or not a hair that sinks at first may float later on is not predictable, so I don't want to encourage you to try to predict a result based on whether it sinks and then floats. That's not accuracy.

Can you get an accurate result with the float test?

I am inclined to say no. If your hair is very porous like the porous hairs I selected and if it is very clean, then you might get a "porous" result. But if there is oil or conditioner or hair gel on your hair, or if it is just a little bit porous - you will not get an accurate result.

If your clean hair is low porosity at the roots and normal or porous near the ends, your hair will probably float, or sink partly - but if it does sink - is that because you dunked it, because there was some conditioner residue, because it came into contact with the side of the container? What other forces are acting on the hair? How porous is it really? More information is needed!

Untreated, low porosity hair floating after 10 minutes. Talk
about water surface tension!

So how do you test porosity? This post goes into depth. In general, lower porosity hair doesn't have damage. It also doesn't dehydrate easily - and that means it doesn't get dry on the inside and brittle. Lower porosity hair doesn't soak up a lot of oil and conditioner. But sometimes hair won't "soak up" those things because you've used henna, or because your hair is coarse (wide) and not very flexible (lots of inner support). Lower porosity hair doesn't tend to "take" hair dye or permanent waves or chemical relaxing easily. Normal porosity takes hair dye normally and porous hair takes hair dye very quickly. If your hair is generally very tolerant of just about everything, it's probably low to normal porosity. Most hair is more porous on the ends than near the roots. If your hair always seems to dry out easily and get brittle and break, it's more likely to be porous. If your hair is dyed or highlighted, it's more likely to be porous (but some hair will resist becoming porous with dye and bleach). If you spend a lot of time in the sun or swimming, your hair is probably porous - though it may or may not be as "dry" as you might expect porous hair to be.© Science-y Hair Blog 2015

Powers of observation

Of all the tools and products for hair, your eyes, hands, ears and mind are the most important. If oil and conditioner just sit on top of your hair, if you've never dyed it nor handled it especially roughly, it's probably lower or normal porosity. If your hair doesn't soak up loads of oil and conditioner, but can tolerate whatever a normal amount is for your hair length and thickness and curl pattern without getting greasy immediately and sometimes gets a little dry or lighter-colored, frizzy or flyaway or the ends start to look light (or invisible) - you're probably lower porosity at the roots, normal in the middle and more porous on the ends. If your hair soaks up lots of oil and conditioner and never seems greasy or weighed down and tends to be dry and brittle and always breaking - higher porosity.

At top left, lower porosity curly hair and in bottom, center,
porous, wavy hair with conditioner applied. Blue
arrows indicate where hairs has sunk beneath the surface.
Bubbles tend to appear when products are applied.

You decide how to treat your hair based on your baseline observations and how it responds to what you do to it. This post has recommendations for keeping lower porosity hair or hair that is difficult to moisturize feeling good. This post is about hair that is low/normal/porous and porous hair can use protein (if it's not coarse) and oil pre-wash treatments and deep conditioning to your heart's content. If you use a heavy-handed oil application and see a glimmer of improvement, but you needed to wash your hair 3 times to de-grease, don't swear off oils. Just use less. Maybe a lot less. Observe, make a plan, experiment, observe again, adjust as needed.

Mixed porosity, curly and kinking hair, untreated. Still floating

after 10 minutes.

 Science-y Hair Blog 2015

A porous hair (top, lighter brown, coiled up) and low porosity hair
(bottom, more elongated) with hair gel applied. Both are partly
sinking due to the product and having been dunked under the
water. Bubbles tend to form when products have been applied.

Make the float test more accurate:

• Start with clean hair - swish it around in some water with a drop of detergent if your hair has any products (including oils and leave-in conditioner) on it, then rinse and let it dry before testing.
• Make sure the hair will not come in contact with the edge of the container the water is in.
• Dunk the hairs quickly (and completely) under the surface of the water to break the surface tension.
• If your hair has chemically-treated ends and un-treated roots of significant length, cut the hair in half and test those areas separately.
• Instead of using individual hairs, tie 15-20 hairs together (with a hair if you can) because individual hairs have very little weight - a greater mass of hair can take on more water if it's porous for a more obvious result.

Interpret your result (if following the instructions above):

• Hairs float at 5 and 10 minutes: Low porosity or low-normal porosity. Henna may give a low porosity result. Or may also be lower porosity roots and more-porous ends. Re-test the ends and roots separately!
• Hair partly floating, partly sinking: Possibly more-porous ends than roots if just one end is sinking, or porous hair if half or 2/3 of the hair seems to want to sink. Re-test the ends and roots separately!
• Hair partly sinking or seems to be just under the surface at 10 minutes: Porous

©Science-y Hair Blog 2015