Effect of Ca++ ions on the water retention of alginate in paper coatings

The water retention properties of starch solutions containing Ca++ complexed alginates were investigated. The viscosities and water retention properties were found to be considerably higher for the complexed alginate than for the non-complexed alginate, but the complex was easily destroyed upon the addition of a sequestering agent. The water retention of the alginate could be manipulated with the level of Ca++ ion added, with more ions providing better water retention. Greatly reduced levels of the complexed alginates provided better water retention than the non-complexed alginates. This is of commercial importance as lower levels of complexed alginate are required to obtain the same level of water as a non-complexed alginate.