a treatment method for polyene resins used in thiol - ene formulations , especially norbornene resins , significantly stabilizes thiol - ene compositions made from batches of polyene resin which otherwise give compositions with poor dark stability . the treatment comprises contacting the polyene with an amphoteric treating agent selected from the group consisting of silicated magnesium oxide , basic aluminum oxide , silica gel , magnesium oxide , magnesium hydroxide , calcium oxide , calcium hydroxide , barium oxide , and barium hydroxide , and then separating the resin from the treating agent prior to mixture with a polythiol to form a thiol - ene composition . the treatment method significantly reduces ionic content in polyene resins , particularly chloride ion but also sodium and potassium ions . consequently , treatment is also beneficial with polyene resins which do not produce substantial dark stability problems . reduction of the ionic content of the resin is desirable to produce cured thiolene polymers with low electrical conductivity and low corrosiveness .