I use two brands mainly because my clients are split right down the middle.
I have CND Brisa: amazing cover colours, bonus- using additives you can create an unlimited amount and range of colours, light weight, durable, easy to apply, stays put so no leakage into the sidewalls, very easy to file for rebalances/infills, even the most heavy handed clients get 3 weeks, they could go longer but that is just a bad idea
My next go to is LCN, those clients that don't fit anything else WILL keep their LCN Gels on, it actually wears like an acrylic. It is easy to customize, Bondique is great for lifters, Cosmique has moon dust which gives it unparalleled strength, Black Diamond Bondique is excellent for NNO and my fave is Fibrique express Repair, which contains tiny little fibres to give elastic support or to mend a broken nail. These are, except F.E.Repair all One component which allows you to use as a base, builder and sealant.
They have 100s of colours to choose from which eliminates the need to make your own colours.
Cleen Cheeks Spa
