For general convenience gels have been divided into two groups: 1 phase gels and 3 phase gels. However, this division simplifies the matter
3 phase gels are divided into:
1. undercoat/prime layer, Bonder (it is applied thinly or very thinly, depending on the brand),
2. building layer, Builder (few coats applied to get nice nail thickness),
3. glossy layer, Gloss (a liquid gel).
1 Phase gel it’s a gel that has got the properties of all three gels. This gel is Bonder, Builder and Gloss in one. You should apply few coats of it to get proper nail thickness..
You can also use it as a 3 phase gel. Just apply your favourite undercoat (Bonder), build the nail with 1 phase gel and to finish add a gloss coat of your choice. The division mentioned above is a little bit simplified as there are also 2 phase gels (Base and Builder in one gel or Builder and Gloss in one). One can also use two gels to build a nail (first the thick builder gel and then thinner gel to smooth the nail surface) next correct its shape with a file and apply Gloss. To get the best effect, I always recommend proper hardening under a high quality lamp.