The best way to explain how gels work is to compare them to how acrylics work, and the difference between the two processes. The heart of the matter is in the difference between hardening and curing. Products that are hard (but not cured) are unstable until they cure, thus they must be handled with care until they do so!
Hardening means to simply “make rigid”, while curing means “complete polymerization” and an end to any internal chemical processes.
As an example to the difference between hardening and curing: Consider a new cement driveway. It is hard in a few hours and we can walk on it, but it is not cured for at least 3 days. Thus we are instructed to not drive on it until it is cured. As any cement-worker (or disgruntled home owner who didn’t follow the rules) will confirm, driving on it before the 3-day curing period will put minute cracks in the foundation and throughout the structure (this damage is irreversible and permanent). These problems will not be visible right away, but at some point in the future the microscopic cracks will get larger and larger. Eventually the cracks will greatly reduce the life expectancy of the cement, rendering it useless, and also cause it to become aesthetically unappealing (i.e., ugly)!
Are you old enough to remember old-fashioned dental filling procedures? This method required the dentist to mix a liquid and powder; this was then applied to teeth and allowed to harden. The dentist would then warn the patient to not eat on it for at least an hour, and to avoid hard and sticky foods for the next few days on that tooth. In contrast, now consider modern light-cured dental fillings: The pre-mixed resin is applied to the tooth, the U-V light held up to it (to harden and cure it), and the filling is now hard enough to leave with no eating restrictions from the doctor! As you can probably guess, just as the first liquid/powder acrylic systems evolved from the dental industry, so too did U-V gels for fingernails come from ever-advancing dental technology.
Now, on to specifics: Traditional acrylics harden in about 10 minutes, but they do not and cannot cure for 24 hours or more (72 hours to as much as 2 full weeks for some products!). Because they rely on heat (from room temperature and body heat) to initialize and continue the polymerization process, rapid polymerization and cross-linking (curing) is not chemically possible in these systems. Acrylics harden by cross-linking the liquid monomer around the powdered polymer. Think of the powder in acrylic nails as metal scaffolding (strengthening rods) and the acrylic liquid as cement. The cement (monomer) is poured in and around the scaffold (polymer), and then hardens around it. The liquid and powder in acrylic systems do not actually mix in the traditional sense, thus the powder can be a weak-link if the monomers do not encapsulate it thoroughly (thus why mix-ratios in acrylics are extremely delicate and important).
Thus, acrylic nails are only hard and not cured when a nail technician does the finish work (filing and buffing) on them, so the acrylic can be de-stabilized, preventing it from curing correctly, and leading to structural and foundation problems (microscopic cracks invisible to the naked eye). As in the cement example above, these problems then lead to product breakdown in the future, e.g. lifting, breaking, etc. The more finish filing a tech does on acrylic nails, the more potential damage to the nail. (Thus why it is said that techs should sculpt with their brushes, and not their files!) The problem is then compounded when the client goes on with her day (and even weeks), using her hands and putting even more pressure on the un-cured acrylic.
Gels, on the other-hand, are pre-mixed (no ratios to master or mess up); made by pre-joining monomers into chains that are up to several thousand monomers long (oligomers). These oligomers are then mixed with chemical initiators tuned to a specific bandwidth of UV light, which causes the oligomers to cross-link must faster than their thermal-set acrylic cousins. Within 20-30 seconds the gel has formed a rigid surface coating (hard to the touch), and then it only takes an additional 1-3 minutes (per gel layer) forthe gel to completely cure.
Since gels are cured completely during the service, filing on them for finish work (and the client using her hands after leaving the salon) will not de-stabilize the gel. Thus gels are less prone to breaking and lifting.
Just as the dental industry has evolved from liquid/powder systems for filling teeth to pre-mixed light cured resins (gels), so goes the nail industry! Continue reading in this website for everything you need to know about U-V Light Cured Gel Nails!
How Do U-V Gels Work?
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