Slip solution is the liquid used with polygel — the hybrid product between acrylic and hard gel. Polygel comes out of the tube as a dense putty that does not self-level; the tech dampens a brush in slip solution so the product can be pressed, sculpted and smoothed without sticking to the bristles. The name is literal: it provides slip.
Unlike acrylic's monomer, slip solution is not part of the chemical cure — polygel hardens only under the lamp, giving the tech unlimited working time. That is why polygel is beloved for careful sculpting and why it is nearly odourless compared with traditional acrylic. If you see a tech working a clay-like product with a wet brush and curing it under light, you are watching polygel and slip solution in action.