Inhibition layer and no-cleanse gels

Question: I was taught that the inhibition layer on many UV coatings is there because the product cures from the nail plate up and it can’t cure where oxygen is present, leaving a thin, and sticky, uncured inhibition layer. What about no cleanse gels?  Why don’t they have an inhibition layer?

Answer: What you were told is mostly correct.  UV nail products cure by UV exposure. During cure, UV energy is present at all layers inside the UV gel coating, so all layers are simultaneously curing throughout the entire nail.  It’s a myth that UV gels cure from the top down or bottom up.  I’ve heard both, and neither of these makes scientific sense. 

The rest of the points you’ve made, I agree with. The sticky layer is due to oxygen in the air. Oxygen can block the curing process near the surface to keep the upper layers from properly curing.  Because oxygen in the air blocks the curing process, this layer is properly called the “oxygen inhibition layer” or “inhibition layer”, for short. This “sticky layer” is actually an improperly cured layer of UV gel. It has a gel-like consistency because this layer is less than 50% cured. UV gel nail coatings harden when they are more than 50% cured. It’s important to understand that “hardening” of the nail coating does not mean the coating is properly cured. This is important because this improperly cured UV gel, e.g. inhibition layer, has the potential to cause adverse skin reactions such as allergy or irritations. Skin contact should always be avoided with uncured or partially cured nail coating products, including dust and roll-off from filing. Avoid laying your arms in these dust or roll-off, or you may develop a skin sensitivity that could become permanent.

It is possible to formulate a UV gel that doesn’t create an inhibition layer, but this creates big disadvantages. These formulas have a much higher tendency to overheat (exotherm) and burn the nail bed, which can lead to onycholysis. This can reduce the color stability of the coating, and may cause it to become brittle over time. Also, the ingredients used to counteract the effects of oxygen can have a higher tendency to cause adverse skin reactions, so be especially cautious of prolonged or repeated contact with these uncured UV gels.  I also recommend that you use caution when removing the sticky inhibition layer. Using alcohol-soaked pads to remove this layer can lead to skin contact with fingers and increase the potential for irritation or allergy. This is why I recommend using a plastic-back cotton pad or wearing disposable nitrile or vinyl gloves to help avoid skin contact with this uncured layer. Any type of uncured/improperly cured UV gel can cause adverse skin reactions if prolonged and/or repeated contact occurs.  Remember, nail coatings that cure without an inhibition layer can have a higher tendency to cause skin sensitivity so avoid skin contact.  

When properly applied and cured according to the manufacturer’s directions, all UV gel products can be used safely; however, this requires proper use and requires nail technicians to take care to avoid skin contact with the uncured UV gel, dust, and filings. Failing to properly apply and cure UV nail coatings is a major reason for adverse skin reactions to such products. This is true for any UV-curing nail product since any of them can cause adverse skin reactions and there are no exceptions to this rule. Even so, it is easy to avoid these problems when nail coatings are properly applied and correctly cured. Skin sensitivities are generally due to improper handling or improper cure of UV gels.