Thursday, July 29, 2010

The chemistry of our nails

The normal nail contains four major parts - the nail plate, which is the visible external part of the nail; the nail matrix, which is the living part of the nail at the root; the lunula (or half-moon) that is the visible front part of the nail matrix; and the eponychium (or cuticle) that forms a protective seal. (There are a few other parts, and you can see them here if you click on my lovingly hand drawn picture of the nail.) This picture leaves out the onychodermal band, which is that band of skin that helps attach the nail to the nail bed at the top of your finger. And the paronychium, which is the skin around the nail.

Much like our hair, our nails are dead by the time they leave the nail matrix, and the nucleus of the cells are completely gone by the time our nails reach the tip of our fingers. They're made up mostly of a type of keratin called "hard keratin" and contain more sulphur than the keratin found in our skin. Nails may contain small amounts of calcium, iron, and zinc. The shape and strength of our nails are determined by the length, size, and thickness of the matrix, while your fingertip shape determines the shape of the nail plate. If the tips of your fingers are rounded, you'll have more rounded nails; if they're square, your nails will take on a less rounded, more square appearance.

The flexibility of our nails is all thanks to phospholipids, which make up a major component of the cell membranes in our body. Phospholipids are partially permeable, and water can pass through our nails far more readily than our skin - you may have noticed this after a bath or washing dishes when your nails swell up and feel a lot softer than normal. Cleaning agents - like dishwashing liquid, bleach, and ammonia - can cause them to become dry and brittle as you remove the protective phospholipids and lose water.

Phospholipids are natural surfactants and emulsifiers consisting of an alcohol (like glycerin), one or two molecules of a fatty acid, and a phosphoric acid compound. Lecithin was the first identified phospholipid and the main source of it is from soybeans or egg yolks. Lecithin contains about 60% to 70% phospholipids. Lecithin softens and refattens the skin, offering a non-greasy, long lasting skin feel.

There is no growth cycle for our nails in that they grow continuously  - about 3 mm per month as long as the nail matrix is undamaged. Our toe nails grow about 40% as fast, about 1.2 to 1.5 mm per month. (A finger nail takes about 4 to 6 months to grow from the nail matrix to the tip of your finger. Toenails can take between 12 and 18 months). Growth is influenced by the weather and season - they accelerate in warm temperatures, slow when it's cold - and age, growing faster in the young. Using your nails doing something like typing can accelerate the growth, and our nails always grow faster on our dominant hand. 

Two of the main enemies of your nails are exposure to water and using them as tools to pry open things or remove nails from wood with your bare hands (yes, I'm guilty of this one). Water is both a friend and an enemy to nails. They contain about 7% to 12% water (compared to 15% to 25% in our stratum corneum) and, as we know, they are highly permeable to water. Too little hydration results in dry brittle nails; too much results in soft, opaque nails that bend easily.

The normal nail is described as being hard, flexible, and elastic, which gives good resistance to microtraumas (those white spots you get on your nails - they're caused by little bumps into things, not by a lack of calcium). This might seem like a weird description - how can nails be hard and flexible at the same time? If you can accidentally bang your fingertip into the wall and feel as if your nail has bent backwards, yet you don't have any breaks - well, that's the only way to describe it. If it shatters, your nail is dry. If it bends and stays there, your nail is too hydrated.

I'm fortunate in that I have incredibly strong nails that I cut when I feel like it or when they're getting annoying (which is right about this time because typing gets irritating). Everyone asks me what I do to keep them strong. Nothing. I rarely paint them, I don't get manicures, I use them as tools, especially when I'm crafting. (I polished my nails for years and used whatever was inexpensive to remove the polish, and my nails stayed strong.) I was born with the genes necessary to give me strong nails. I do have a few suggestions though...
  • Don't file your nails - this weakens the edges and gives them a chance to develop what I call cricks or little ragged bits that catch on everything. I only file my nails when they get one of those little cricks. Be happy with your natural shape! 
  • Don't bite your nails - again, this weakens the edges. 
  • Don't clean or use gloves if you must - protect your nails from water and from cleaning products. 
  • Stay away from acrylic nails - the adhesives used can lead to brittleness of your natural nails (if you're getting tips painted on) or the acrylics used in sculpted nails can lead to softness as accumulated liquids cannot evaporate. On top of all of this, the adhesion of the artificial nail is stronger than that of the nail bed to the onychodermal band, and it can pull that from the nail plate. 
Join me tomorrow as we delve into the exciting world of nail care products! 


Sarah {The Student Knitter} said...

You're seriously from Chilliwack???!!? You have no idea how amazed I am! I'm heading home to Chilliwack on Monday! I live in Virginia now. I picked up your link from Soap Deli News and almost spat out my drink when it said you operate out of the Chilliwack and Yarrow libraries! Making my own soaps, makeup and shampoos has really been on my radar lately. I'll try to stop in for one of the session in Chilliwack while I'm in town! We're talking about the same one right? Just outside Vancouver?

Susan Barclay-Nichols said...

Hi Sarah! I hope there's only one Chilliwack - you have to admit it's a pretty unique name! My groups are for teens and tweens, but you're welcome to stop by and help out (and learn while we make stuff)! I would happily do some adult classes, but there's really nowhere around here to do it other than the library, and we can't use scents in the Chilliwack location!

Welcome home! It's warm - but probably warmer in Virginia, so you probably won't notice it!

Terri daeffler said...

So I'm a nail tech tell me what you would recommend to repair weak brittle splitting nails. I'm trying to come up with a new conditioning treatment in my salon.

Susan Barclay-Nichols said...

Hi Terri! Take a look at some of the other posts on nail care - click "newer post" at the bottom of each post - to see some of the recipes I suggest for nails. Or do a search for nails and see what comes up!

Kim said...

Would making a thick body butter cream (one with water) be bad for nails? Should we stick to anhydrous products? You mention that water is both enemy and friend. Would adding keratin to nail products help strengthen it? What about bamboo extract/bioferment/isoflavones?

Susan Barclay-Nichols said...

HI Kim! Nope, one with water is good for nails, too. I use a body butter with bamboo isoflavones - this recipe for the body butter - and love it for my nails. Keratin or proteins can be a great choice, although I haven't researched enough to know whether or not our nails can use those proteins. They will make a product feel silkier with more film forming abilities, though.

Having said this, I have really strong nails. Strong as in I only cut them when they start to drive me crazy. There's a picture of them in this post...