Heat spikes in gel nail services: why they happen & how to avoid them

What is a heat spike? Why can a burning sensation be felt by clients when a gel product is curing? Dani Bailey, nail educator & recipient of The Shooting Star Award at the Scratch Stars Awards 2024, explains…

In August, Scratch posted an opportunity on Instagram for people to send in their questions for this column – and one in particular caught my attention: ‘Why does turning your hand upside down make a heat spike less intense?’. Interestingly, I have received the same question from a student in Brazil.

First of all, we need to understand why heat spikes happen…

Remember my column about nail product polymerisation? All artificial nail enhancements depend on this chemical reaction to go from a liquid form into a solid coating. This chemical reaction produces heat and is called an exothermic reaction (‘exo’ meaning outwards and ‘thermic’ meaning heat). Every time a monomer or oligomer attaches themselves to another, a little bit of heat is released.

There aren’t just a couple of exothermic reactions taking place at once during the polymerisation process. There are thousands, if not millions, happening – and sometimes that heat is felt at the nail bed. This should always be avoided, because the heat produced can be so high that it can burn the nail bed, causing onycholysis (separation of the nail plate from the nail bed) and opening the nail apparatus to all sorts of pathogens.

So, how do we avoid heat spikes? Here are my tips:

• Work with thin layers of product: If you keep the number of reactions down, the heat won’t be as intense. Working with thick layers of product will produce more reactions and therefore more heat.
• Never over-file the nail plate: A healthy nail plate can act as a buffer between the nail bed and heat from the product.
• Always use matched systems: Mixing incompatible monomer liquid and polymer powder can cause the reaction to happen too fast – which will translate as a heat spike. The same happens for products cured by UV: if the lamp used is not intended for that product and releases an intensity of energy that does not match the initiators in the product, it will cure too fast.

This is why some manufacturers have developed lamps which have a ‘low heat mode’. These lamps start emitting UV radiation in smaller quantities, as a sort of warm up, which makes sure the product starts its cure slowly, without producing a heat spike.

The hand upside down trick or asking the client to start the cure with their fingers just outside the opening of the lamp, before bringing them in slowly, serve the same purpose. These limit the intensity of UV rays that can reach the product, slowing down the chemical reaction. Imagine a camera flash: if you step away from the camera when the photo is being taken, less light will reach you – or if you’re closer, the opposite is true.

These ‘quick fixes’ are known far and wide – but let’s make sure they come with a warning: if the start of the cure has been carried out like this, without the manufacturer’s instructions to do so, make sure the client returns their hand in the normal position to the lamp for a full cure.

Failure to do so will result in the product not being fully polymerised, which can cause service breakdown and increase the likelihood of allergies. It’s always best to follow manufacturers’ instructions, as these have been tested in a lab.

However, if a client still fells a heat spike after following this advice (some people are just naturally more sensitive), make sure they remove their hands as soon as it is felt – to avoid damaging the living tissue under the nail plate. Never ever ask a client to endure the burning sensation, as the consequences can be devastating.

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