Lou,
I understand why you and many others say this, but you don't have the knowledge to make an informed decision:
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Some scientists in the USA visited nail salons, and did some measurements on their UV lamps. Most of these were the traditional 9W bulb based lamps, but the principle is the same for LED-UV lamps. The numbers on top of the bars are the Watts/number of bulbs. Notice most of these are 36W lamps.
The diagram shows the amount of UV Illuminance (like brightness) measured in 5 different positions in each lamp. So when you look at a bar, the top is the brightest position and the bottom is the least bright. The bigger the bar - the more different in maximum and minimum brightness.
Less imagine that a gel requires an UB Illuminance of 10 mW/cm3 to cure correctly. Which UV lamps would do this? UV lamps 3, 6, 9, 12 are all below this line! But UV lamps 1, 3 4, 5, 13, 14, 15, 16, 17 - will only provide a correct cure at the brightest positions in these lamps. At other positions they will under cure. Only lamps 7, 8 and 11 are bright enough in every position.
Remember, under curing not only means less reliable nails, it also produces under cured gel dust that causes allergies. And it the smallest invisible dust that floats in the air, that can land on any exposed skin - which is why people get reactions under their eyes and on their neck. E-files produce a lot of this micro dust.
Now as far as these nail salons are concerned, they think their UV lamps "work" because the gel / GP becomes hard. But gels become hard enough to file when only cured 50%. So it is impossible for know if a UV lamp correctly cures a gel, unless it is tested in a scientific laboratory. How many brands that simply buy product from factories and slap on labels, understand this or have access to a scientific lab and a chemist....?
Why is it that very few nail schools teach this critical safety information?
What all of this means is that the UV lamp has to be matched to the gels, or the gels matched to the UV lamp. This process of testing and matching is time consuming and expensive - this is why serious companies only sell one UV lamp.
I'm a manufacturer, so I can understand if some people (who don't know me), doubt what I say. So here is a link to an article published in Scratch.
http://professionalbeauty.co.uk/sit...l-kits-lead-to-increase-in-allergic-reactions
Here is what the President of the British Society of Cutaneous Allergies had to say:
“The lamps provided with kits are very specific to the individual gel-polish system, so when they buy polishes from different systems the lamps don’t work as well and they’re at much greater risk.”
I.e. UV lamps and gels must be matched.