Water is a universal solvent and is required for almost everything we do in our daily life. Water has a unique chemical nature. It is a polar molecule, and due to its polarity, it dissolves most chemicals, minerals, and ingredients. Polarity also makes it an excellent wetting liquid that provides its detergency and ability to clean and remove debris from dirty clothes or our hair and skin. However, water quality varies depending on the source. Water quality is defined by the presence of organic or inorganic materials present in water, and it has an immense impact on our health and overall life.
As water is the sole solvent for cleansing hair and skin, hard water will have a negative effect on skin and hair. But what is hard water, and how does it affect our hair?
Hard Water, What Is It?
The simple definition for hard water is "water containing significant amounts of dissolved minerals." Calcium and magnesium are the two metal ions mainly responsible for this. The presence of these metallic ions changes the physical and chemical properties of water, eventually altering its potential power for detergency and cleansing. Water containing high levels of calcium and magnesium ions is called "hard water," and the measurement of these minerals in water describes "water hardness." The sum of both calcium and magnesium is determined experimentally and is called "total water hardness."
So, the question that follows is, why is their presence called or termed "hard"? The answer is because both calcium and magnesium make it "hard" for water to clean objects. For example, you might have observed washing your hands with regular soap under tap water, and some white precipitates or scum may appear instantly, which is called "soap scum." Soap scum is long-chain fatty acid salts of calcium and magnesium which become insoluble during washing. So, under these hard water conditions, your soap cannot clean properly, and that's why the term "hard water" evolved because it makes it hard to do the cleaning.
The World Health Organization (WHO) and almost every country have standard limits for both calcium and magnesium in water. Water containing 0 to 60 mg/L (milligrams per liter) of calcium and magnesium is classified as soft, while water having more than this is hard water. Water hardness increases as the amounts of both metal ions also increase.
Cause of Water Hardness: Source of Metal Ions
The main cause of water hardness is carbonates, bicarbonates, and chloride salts of calcium and magnesium. These metals are abundantly present in the earth's crust. They exist in rock, e.g., limestone, chalk, gypsum, and dolomite. A straightforward explanation for their presence in water is when rainwater dissolves these minerals. Wastewater from industry, sewage, and agricultural waste is another source of these metal ions.
Metal Adsorption on Human Hair
There are two assertions for the metal content of human hair. First, the metals present inside the hair fiber are due to natural keratinization and biochemical processing in the hair follicle. Second, the microscopic examination of different parts of hair fiber reveals that metals present are bonded to multiple amino acid sites. These metal levels are minimal, and they have a vital function in the hair life cycle.
Most of the metals on hair are found at its outer surface, the cuticles. Scientific studies have identified various metals such as calcium, magnesium, copper, and manganese, etc. It is believed that these metals get adsorbed at the hair surface from external sources. Tap water is thought to be the main player here. If the calcium and magnesium level is high in your tap water, your hair absorbs these metal ions. Various research groups have reported these findings in scientific journals. In addition, bleached and damaged hair is found to have higher metal content.
Calcium and magnesium metal ions are cation, meaning they have positive charges. The amino acid sites on hair have negative charges. What do we know about magnetism? Opposite charges attract, which means that these metal ions will bind electrostatically to the amino acid sites in the hair structure. Positively charged cations of calcium and magnesium bind with negatively charged carboxylates sites of amino acids. Damaged hair, particularly the damage done by hair bleaching, permanent dyeing, and alkaline treatments, has a relatively higher number of negative sites, which is why damaged hair has higher amounts of calcium and magnesium compared to undamaged hair.
Impact of Hard Water on Hair
Water hardness has serious consequences for our hair care, such as;
- Metal adsorption at the hair surface alters the surface properties of hair.
- Chemically treated hair has higher metal uptake leading to potentially undesirable metal build-up.
- Metal adsorption hinders the uptake of essential active ingredients. In addition, they compete against cationic ingredients for binding sites as both metal ions and conditioning agents target the same negatively charged sites. Meaning, a high presence of calcium and magnesium at the hair's surface will undermine the performance of your conditioner.
- Hair with higher metal levels demonstrates poor curl retention or difficulty in maintaining the desired hairstyle, thus highlighting the importance of water quality for curly hair.
- Hair scientists have reported that hair becomes stiff and difficult to style. This is potentially due to changing hair charge density and having a uniform coating of hair styling products at the hair surface.
- The overall sensory features, touch, and feel for hair also changes.
How to Control Metal Uptake?
Simple steps you need to minimize hard water metal uptake on your hair:
- "Prevention is better than cure"; avoid hard tap water. If you have a higher measurement for total water hardness, try to remove them from your tap water. Water treatment units for the home are readily available and can significantly improve your water quality.
- Once a week, wash your hair with anti-residue shampoo to get rid of any metal buildup. The chemical agents that can selectively bind to calcium and magnesium ions and remove them from the system are called "Chelants." A good example is Ethylene-diamine-tetraacetic acid (EDTA). EDTA is available in salt forms such as monosodium, disodium, tri, or tetrasodium EDTA salt. The addition of salt into a formulation is easy, and that's why they are preferred. Other examples are Ethylenediamine-N,N'-disuccinic acid (EDDS), or Etidronic acid (HEDP). Phytic acid is a new and green chelant, which is sustainable and environmentally friendly.
- If you want to use a product with more natural ingredients, we suggest using our Bounce Curl Turmeric Hair Detox Mask. We wanted to tackle hard water using natural ingredients. Our detox mask has a very high content of organic apple cider vinegar. Apple cider vinegar can decrease mineral build up (such as calcium and magnesium), which means it’s a natural chelating ingredient. Hard water is composed of negatively charged calcium ions so it is highly reactive with acids like vinegar. It’s been shown to break down minerals such as magnesium and calcium which then can be rinsed off your hair. Not only does our formula contain acv, but it contains a lot of other organic ingredients such as aloe to balance moisture and shine. Other antioxidants like turmeric and charcoal to absorb sebum too!
- 3 ways to use our detox mask:
- Scalp detox
- Add to your shampoo
- Full scalp and hair detox
- Keep it in for 10-15 min and rinse!