St. Louis union painting contractors representing 85 percent of the union painting hours worked in St. Louis rejected a counter-offer by Painters Local 2 last Thursday. With no agreement in sight and a contract expiration on Wednesday, contractors are prepared to continue work under the existing agreement. Representatives of Painting and Decorating Contractors of America Chapter 2/Finishing Contractors Association and the union met Monday evening. Police are investigating reported vandalism at the offices of a member of the contractors' negotiating committee. 