Some people only eat burgers

This article isn't about food. It's about nail salons and why customers make different choices.

The meal on the left represents the typical low-cost salon. It's fast and convenient but as you add up the options it's not as cheap as you expected. The environment is noisy and there's a good chance you will have to wait in a queue behind people who don't know what they want, misplaced their purse or who think the server is there to provide conversation as well. Although you don't want to know what part of the animal was used to make the burger, you assume that because the authorities didn't close them down that the food is safe. Safe is a relative term. In most cases the authorities won't come until a customer becomes ill. And that customer may be you.

The meal on the right represents a high quality professional nail salon. Perhaps even award-winning and perhaps the chef is the actual owner, not part of a Quik-e-Nails franchise.

The beautifully presented meal is a tuna on watermelon whatsit. You know what the main ingredients are and you also know that the person who made this probably studied their craft for years. You are confident that the kitchen is clean and that the food is prepared safely (if you are not sure, go inspect their washrooms, it's probably a good indication)

As you arrived for your appointment, you were greeted and led to your table. The server presented a menu and was trained to give advice about both the food and wine offered to ensure your total satisfaction. Perhaps they asked if you had specific dietary requirements. The meal is beyond your expectations and the service is discrete but attentive. The restaurant has a nice calming ambiance, so that visiting it became a pleasurable event and perhaps a special memory.

When we travel, we prefer to save money on the hotel but spend more on a good meal and hopefully have a delightful culinary experience. That is our priority and choice.

But some people prefer burgers. Sometimes that's a question of price and affordability or convenience.  Perhaps they don't feel comfortable in restaurants or maybe they simply think a burger tastes better than any chef prepared meal. Another reason could be that they are not educated to understand the difference in quality, education, skill and service that creates a different kind of value.

Whatever. You are not going to change them. So don't waste your time or get frustrated trying to sell a cordon bleu meal created by a passionate professional to the burger eater. They don't want or understand it.

Choosing a UV lamp to make gel nails

Every manufacture recommends that you buy their UV lamp, just as they also recommend that you only use their primer, bonder, etc. But is this because there are good reasons for this advice? Or, is it because the manufacturers simply want to make more money?

In this article I will explain why there are differences between various UV lamps, and I'll explain why CCFL and LED UV lamps are different from the traditional CFL UV lamp that you probably use right now. I'll also talk about the chemistry of gel nails and explain how all of these parts all fit together.  

It's all about the chemistry

Lets use the example of baking a cake. It's chemistry too. If you change the type of ingredients or the amount, or use too much or too little heat, then the cake won't taste like it should from the recipe. Remember that heat is just another form of energy which is used to make a chemical reaction, in the same way that we use UVA light to make a chemical reaction with nail gel. 

Fortunately, we can use ovens that are manufactured by different companies and still expect to bake a nice cake. 200 degrees C at 60 minutes exactly dictates the amount of energy required and will be the same amount of energy whatever brand of oven we use. If we are lucky enough to own a more expensive convection oven that uses a fan to distribute the heat, we know that type of oven is more efficient and we will need to use a shorter cooking time to get a good result. 

Unfortunately, creating a repeatable and good chemical reaction using UV gels and UV lamps is more complicated than baking a cake. That's because :

• UV lamps are available that generate different amounts of energy
• Different UV lamps and UV emitting devices have different levels of efficiency
• Photoinitiators in gels and gel polishes require a specific wavelength and intensity of  UV light energy to work

So unlike the cooking example where 200 degrees at 60 minutes defined the correct amount of energy to bake the cake, if we use the wrong UV lamp to cure our gel then the result has four possibilities:

• the gel doesn't cure. Not enough UV light is generated to cure the gel, or the generated UV light wavelength does not match the wavelength required by the gel or gel polish. 
• the gel is not fully cured and may be soft near the nail plate. The nail enhancements will be weaker and will have less adhesion to the nail plate that can cause lifting problems. Uncured gel that touches the skin increases the risk of allergic reaction. 
• the gel is cured perfectly to create the most reliable and best looking nails possible for that specific gel product
• the gel is cured too much. Over curing increases the risk of excess heat that can cause the customer pain and product lifting that can cause bacteria to thrive. 

Photoinitiators - the crazy eggs in the UV gel cake

Photoinitiators are chemicals are added to gels to start the chemical reaction. When UV energy is applied in sufficient quantity, these photoinitiators break down to create free radicals that then attach themselves to the soft gel oligomers to create longer chains of the cured gel polymer. 

But like those strange eggs, different photo initiators require different levels of UV energy to break down and to make free radicals. Also, different photoinitiators need UV that has a particular UV light wavelength. So to create the most effective chemical reaction the photoinitiators and UV light source need to be compatible.

If you are confused by the word wavelength, it's the different wavelengths of light that make the colors of a rainbow, or make the light visible or invisible to the human eye. Next time you are at the beach, notice that some waves change slowly and have a longer wavelength, but as the sea approaches the beach the wavelength increases and produces those fast little waves before they break on the sand.

Why are different photoinitiators used?

Before gel polishes, nearly all hard and soak-off gels contained photoinitiators that required UVA light having a wavelength between 350 to 370 nm. A nanometer (nm) is a unit of length that is 1 meter divided by 1,000,000,000. 

As traditional UV lamps using Compact Florescent Light (CFL) light bulbs produce a range of light in the UV-A spectrum with wavelengths between 320nm to 400nm. Incidentally, the reason why we can see a purple light from our UV lamps is because it also produces light with wavelengths above 400nm that is within the light range visible to the human eye. What we can't see is are the UV wavelengths below 400nm that actually cures the gels. Take a look at the diagram below:

Image courtesy of NAILS magazine

So why do most gel polishes contain photoinitiators that need UV light with a wavelength of 390nm? 

The answer to this seems to be connected to the introduction of LED UV lamps. Light Emitting Diodes are semiconductor devices that are more rugged than glass bulbs. Also because they use less energy, work for up to 50,000 hours and don't contain mercury, they are kinder to the environment. 

But, until now it was only possible to buy LED's that created a peak of 405nm UVA at a low price. Although LED's exist that create UVA at a peak of 365 nm are available (and could be used to cure hard gels) - they are too expensive today to be used in UV nail lamps. So the gel polish manufacturers designed their product to work with the available LED UV lamps because these offered a shorter curing time of between 30 to 60 seconds, compared to the traditional CFL UV lamps that still need curing times from 120 to 180 seconds. 

What are LED UV lamps faster?

If you place your finger over the end of a water tap, the jet of water is much more intense than before because you have focused the water energy. It's the same idea with LED's. As these generate light over a much smaller range of wavelengths, the light intensity is greater than a traditional UV CFL lamp that blasts light across a much wider spectrum - much of it unused to cure the nail gel. So a 9W LED UV lamp, is going to cure gel polish much faster than a 9W CFL UV lamp. 

Less shine with LED?

Having tested a significant number of LED UV lamps and different gel polishes, we noticed that the top gel shine was worse on LED cured nails, than nails cured using CFL or CCFL UV lamps. 

CCFL UV lamps

CCFL or Cold Cathode Florescent Lamps are the new kid on the block. Like CFL UV lamps they use an excited gas to generate light inside a glass container. But like LED devices, CCFL have a long lifetime of between 30,000 to 50,000 hours. 

However they have one advantage over LED's; CCFL UV lamps generate UV light over a wide spectrum from 350nm to 400nm - so like CCL can be used to cure both hard gels and gel polishes. But CCFL UV lamps will not cure gel polishes as quickly as the best LED UV lamps. 

CCFL UV light bulbs are available in two shapes depending on UV lamp that is purchased. Notice that the UV lamp on the right also contains LED's:

UV Lamps - design is important

So far we've discussed the different devices that emit UV light, and how the UV wavelengths cures some or all gels and gel polishes. But let's now look at the two main factors that affect the performance of a UV lamp:

1. the intensity of the UV light that is generated by the CFL, CCFL or LED devices
2. the intensity of UV light that is produced on the nails

It's obvious that a 9W CFL UV lamp will produce less UVA intensity than a 36W UV lamp. But we also need to remember that 9W refers to the electrical power consumed, and is not a direct indication of the amount of UV produced. 

As with most things in life, you get what you pay for so a more expensive Philips or Sylvester CFL UV bulb is more efficient, maintains it's light output intensity and lasts longer than a low cost Chinese UV bulb. 

But the amount of UV light produced is not the only factor. It's also important how much of that light lands on the nail surface. The distance from the nail to the UV emitting device is important because distance reduces the UV intensity as it travels though air. Closer is therefore a better use of the UV created as more will be useful on the nail gel. 

Another factor that can be important is the quality of the reflectors inside the UV lamp. Both CFL and CCFL UV bulbs radiate light in 360 degrees so the reflectors are used to bounce as much UV light as possible onto the nail surface. 

With LED UV lights, reflectors are less important. That's because LED's project light in front of the device that is focus in a narrow area - like a spotlight. But if the LED's are only mounted on the top of the UV lamp, they are unlikely to cure gel on the the thumb nails. For this reason, higher quality LED UV lamps also have LED's mounted in the side walls. 

Summary

As we now understand, the UV lamp is an important part of the nail chemistry. For that reason, manufacturers recommend UV lamps that they have designed or tested to work with their gels. They want their gel customers to be produce reliable nails and avoid potential risks of salon customers developing allergies.

Why do some UV gels produce too much heat?

The Chemistry

Gels consist of oligomors which are short chains of a few thousand monomers, the photoinitator and other additives to give colour, limit yellowing etc. When UVA hits the photoinitiators they break down to become free radicals and generate heat in what chemists call an exothermic reaction (heat producing). It's the heat and those crazy free radicals that helps the oligomers to connect into much longer chains to form polymers. 

Before curing, the oligomers in the gel are unorganised - like a box of dominoes emptied on a table. After curing, the polymers are more organised and the cured gel is smaller - this difference in size is what we call skrinkage. If you imagine making a low wall of dominoes, you can understand that this takes less space on the table. If the dominoes are glued together, you can also appreciate that the wall would be much stronger than the glued unorganised dominoes which don't touch each other very much.

Some gels contain more photoinitators and some contain less. The decision is affected by what curing time is required, the amount of UVA provided to cure, and the chemical efficiency of the exothermic reaction. Using fewer photoinitators means the gel requires a longer curing time, or needs to be used with UV lamps that produce more UVA light on the nail (either by making the UV bulbs closer to the fingernails, or by using more powerful UV bulbs).

Are the chemists trying to kill us?

So we know why heat is produced, but perhaps the most interesting question is why do some gel burn? Did the chemist deliberately produce a material that hurts customers?!

Well know that if the gel is not applied correctly in too thick a layer, that curing will generate more heat. So it makes sense that if the gel is applied in several thin layers the heat will be reduced. But several thin layers of cured gel are also stronger than one thick layer (like rings in a tree, more thin rings produces stronger wood).

We also know that not all customers feel the heat in the same way. Customers with thinner nail plates have less of a barrier and protection against the heat reaching the nerve ends under the nail plate, and feel the heat more.  I also suspect that men are more sensitive to pain than women, from my experience being a guinea-pig for gel tests!

But what about those gels that seem to generate too much heat even when applied correctly on customers who don’t have thin nail plates? An answer for this may be found in an old article by Doug Schoon. In this article, Doug mentioned that most gel lamps used in the USA were 8W, while in Europe it was more common to use 36W.

Now imagine that the chemist developed a gel for an 8W lamp, and put in just enough photoinitiators so the gel cured in a specific time. But then the gel was used in Europe with a 36W UV lamp that generated more than 4 times the amount of UVA light - that would make the chemical reaction faster and generate too much heat!

What this illustrates is the importance of matching the UV lamp to the gel (or developing the gel to match the UV lamp). If this UV lamp and the gel is not matched correctly, either you could suffer under-curing, over-curing and in some cases this would generate excessive heat.

Summary

So in summary, there are several possible reasons why a gel may burn:

1. Gel is applied too thickly

2. Customer has a thin nail plate

3. Customer may be more sensitive to heat

4. A UV lamp with too much UVA power is being used

5. The chemist was not very good, or the product wasn't tested properly ;-)

Footnote

Developing the unique IKON.iQ gels with our chemist helped me to better understand the difficulties to produce the perfect gel. Most low-heat gels in the market have a medium to thin viscosity, and some do yellow during weeks of wear. Trying to produce a higher viscosity gel that was good for sculpting, generated low heat, didn’t yellow and cured in a 36W UV lamp within two minutes was very difficult.

But more difficult still was trying to create a white sculptor gel that could be applied in one layer, would cure in two minutes and that would hold the c-curve shape during and after curing (i.e. very little shrinkage). From our experience, no other manufacturer had created a white gel with all these features.

We did finally succeed with all of our goals, but it took nearly two years and many chemical formulations. We were lucky to work with an exceptional and very patient chemist and also that as the company owners, we were willing and able to wait for as long as it took to create the gels we wanted.