AKRON (March 6)—Two more carbon black companies are raising prices for their products. Columbian Chemicals Co. is boosting prices for carbon black sold in Asia 15 percent, effective April 1, and Continental Carbon Co. is increasing list prices for its furnace grade blacks 19 percent, effective March 10. Both companies cited rising feedstock costs for their decisions. Columbian noted feedstock costs area at historic highs and are being negatively affected by an oil workers' strike in Venezuela and speculation over a possible war with Iraq. Continental Carbon also cited the rising cost of energy and packaging materials for its decision. Columbian is trying to cut costs and improve productivity, but raw materials costs are too high for the black maker to absorb, said Columbian President James P. Berresse.