The present invention relates generally to water soluble polymer powder formulations, and more particularly, to a cellulose ether formulation which in powder form is suitable for direct addition to water-based systems to produce smooth, lump free solutions. The cellulose ethers are crosslinked with an aldehyde crosslinker and include a dry weak acid which slows hydrolysis of the hermiacetal linkage formed by the crosslinker. The selected acid does not adversely affect solubility stability.