Frequently asked questions
Q. What makes a powder fast set rather than medium set?
The terms above really describe the way in which a powder absorbs the liquid ( monomer) and is a measure of the sculpting time , not the overall cure time of the resin. There are 2 main factors which affect the set or gelation time of the powder ( assuming the liquid is constant )One factor is the particle size of the powder, but usually it is the actual composition of the polymer which is the major factor. A fast set powder, usually, is a 100 % polyethylmethacrylate homopolymer, ie a single type of acrylic has been polymerized to make these beads. Such a PEMA bead absorbs the monomer quickly, the beads swelling and gelling quickly.Other polymer beads are made by polymerizing 2 ( or more) monomers together into the bead, and this affects the rate at which the liquid soaks through the bead, and so the sculpting time and gelation time can be slowed or controlled. When 2 monomers are polymerized together the resulting copolymer is often labeled as a medium set powder.Controlling the way the beads are made gives rise to many powders with various absorption and sculpting properties. In the industry, the gelation time, and so the powders, have been labeled as slow, medium or fast set type powders.The size of the polymer beads can also have some affect. In general, the smaller the beads, the more surface area is available for monomer to interact with and so the swelling and gelation is quicker.
Q. What makes a liquid cure or harden faster?
The powder and liquid both contain chemicals which react together to cause the polymerization or hardening of the final mixed resin. Traditionally, this means benzoyl peroxide in the powder bead reacting with an activator such as DMPT in the liquid. As explained in question 1, fast set and mediun set powders behave differently when applied to the nail, but they can polymerize or harden in the same time, for example in 5-6 minutes. The cure time or polymerization time is when the reaction has proceeded to convert the uncured liquid into the final polymer, and this happens with an exothermic reaction, and a clarifying of the resin. ( unless shaded opaque colour )The external factor which can speed up the cure time is the temperature of the components before mixing, the room temperature and the temperature of the nail plate. The warmer any of these are, the faster the cure time may be.Within the powder / liquid system the cure package is carefully balanced, and speeding up the cure is not as easy as simply increasing the catalyst in both sides. The benzoyl peroxide is generally residual inside the beads and this can be present at different percentages to give various cure speeds, but in each case the level of initiator in the liquid is matched to the powder. Increasing such factors could also adversely affect colour stability and yellowing as well as increasing the porosity ( bubbles )Q. Why do some acrylics crystallise?
The term used here really refers to unsolvated or partially solvated polymer beads. This normally is reported when the temperature of the liquid, powder , room or all 3 is lower than usual. Some liquids are basic formulations consisting mainly of a volatile monomer like ethyl methacrylate. Other liquids are more complex blends including ingredients to aid adhesion, flexibility and colour stability, and may contain less volatile materials. Regardless of the monomer, when the material is cold, the solvation, gelation and eventual cure are all extended, the material is more sluggish than when at a normal room temperature.If the liquid is trying to solvate powder beads, and the reaction is taking a long time to commence, the volatile monomers can be leaving the mixture, leaving the polymer beads dry and not fully wetted. In many cases, simply allowing the monomer or powder to return to a warmer temperature can eliminate this, however we would also recommend using a more advanced formulae liquid from Esschem Europes' Cosmetic liquid line.Cosmetic Information
Cosmetic Products
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