"Wrap square in flannel. Stir in rinsing water until desired colour is obtained. Prevents clothes turning yellow" Reckitts Square Blue whitener. Circa 1940s. 4 square cubes within a box. Vintage Reckitt’s Square Blue Reckitt’s & Coleman (Canada) Limited Montreal Made in England 4 Wrapped Squares Unopened New v Stock 120 grams 6 x 5.7 x 2.5 cm