to 12 average carbon number and having 1 to 20 moles of ethylene oxide added polyoxypropylene alkyl or alkenyl ethers having alkyl groups or alkenyl groups of a 10 to 20 average carbon number and having 1 to 20 moles of propylene oxide added polyoxybutylene alkyl or alkenyl ethers having alkyl groups of alkenyl groups of a 10 to 20 average carbon number and having 1 to 20 mols of butylene oxide added nonionic surfactants having alkyl groups or alkenyl groups of a 10 to 20 average carbon number and having 1 to 30 moles in total of ethylene oxide and propylene oxide or ethylene oxide and butylene oxide added the molar ratio of ethylene oxide to propylene oxide or butylene oxide being 0 1 9 9 to 9 9 0 1 or higher fatty acid alkanolamides or alkylene oxide adducts thereof less preferred surfactants include anionic cationic and amphoteric surfactants anionic surfactants are surfactants having a hydrophilic moiety in an anionic or negatively charged state in aqueous solution commonly available anionic surfactants include carboxylic acids sulfonic acids sulfuric acid esters phosphate esters and salts thereof cationic surfactants are hydrophilic moieties wherein the charge is cationic or positive when dissolved in aqueous medium cationic.