Let’s make things clear!
Exploring the role of pH and UV in nail adhesion promoters
When a nail plate adhesion promoter is mixed with water, its effect on the pH of the water is measured. This mixture makes the water alkaline, acidic, or neutral. HEMA is well known for its adhesion promoting ability and will neutralize the pH in the water. Other adhesion promoters can make the water alkaline or acidic. So obviously pH does not determine whether it is an adhesion promoter or not.
Yes, pH sometimes plays a small role, but UV also plays a major role. UV causes the gel to polymerize and certainly promotes adhesion, but UV has no pH. So, there is clearly a lot more to adhesion than just pH.
Understanding the chemistry behind how UV gel adheres to nails
The adhesion is caused by the ingredients in the UV gel. Many ingredients are repelled by the nail surface, but some are strongly attracted to the nail surface. Why? These ingredients chemically bond with the nail surface, which is why they are attracted. The attraction and adhesion is due to the chemical bond with the nail surface, not the pH.
There are three main types of adhesives, listed in order of bond strength:
1. Hydrogen Bonding Although they are the weakest adhesive layer, many adhesive layers working together provide a significant amount of adhesion, but they can be easily destroyed by heat, moisture, mechanical stress, etc. These bonds are constantly changing position, so they are not as strong, but they are still very influential and will always play a useful role.
2. Ionic Bonds They are stronger than hydrogen bonds and are formed by the forces of attraction between opposite positive and negative charges on the compound and the nail plate surface. Their strength is affected by pH, so pH indirectly plays a small role. These bonds, like hydrogen bonds, are reversible.
3. Covalent Bonds By far the strongest of the three types of bonds. Covalent bonds are highly stable, resistant to external factors, and provide the most durable and long-lasting bond. Covalent bonds require significant energy to break and are therefore generally considered irreversible.
Factors affecting the adhesion of nail products
Adhesion is also affected by other factors, such as how well the product flows into small nooks and crannies; a property known as “wetting out.” This important property is improved by properly cleaning the nail plate. So, you can see that many things affect adhesion, including the cleanliness and condition of the nail plate. Well-designed nail products often combine these bonds to achieve the best adhesion possible.
The risks of acidic gel-based nail products
What about so-called “acid gel bases”?
Some of these contain acrylic acid, which uses all three of these bonds to increase adhesion, but I still don’t recommend using products that contain this ingredient. It’s a strong skin irritant and may be the cause of many allergic reactions in the nail industry. In fact, I would guess it’s more likely to cause skin problems than HEMA.
Caution! Avoid contact with skin and never use on split or cracked nails.
