Unless you are a senior citizen or clean clothes for a living, you probably don't know what bluing is. I am neither. So when I ran across this integral component to growing salt cyrstals, I had to go to Google. Apparently as white clothes start to fade, the trace amount of blue emakes the clothes seem whiter to the human eye. These days, bleach has pretty much replace bluing as an household item.
In the state of Iowa, Mrs. Stewart's, the most widely carried brand of bluing, is only found in three store chains. None of them were where I lived. Therefore, this project got shelved for nearly two years.