The distance of migration is inversely correlated with the molecular weight of the protein (small proteins move faster through the gel than large proteins do and therefore migrate further down the gel).
Shellac is the most expensive of the gel nail polishes on the market, and the bottles are half the size of the competition. The higher cost for the salon owner is one reason Truong believes other salons might not correct you if you ask for Shellac but choose a different gel polish when picking your color.
Gel manicure is a type of manicure that uses a coat of gel applied on the nails, with regular polish on top. The use of UV light to cure the gel allows the manicure to last longer. Shellac is a technology invented by Creative Nail Design (CND). It is similar to regular nail polish, but also uses UV light in between coats, which make it last as long as gel manicures.