Tuesday, August 28, 2012

Liquid bluing

Yowza, this has been a busy, busy summer, and I'm way behind on blogging. I have much to write about, but will begin with the most current event: E and I are growing a salt garden.

When I was 12, I had a homework assignment to design and carry out my own science experiment. In browsing books for ideas, I came across instructions for a salt garden, with a recipe for a liquid concoction that, when spooned over cut-up sponges, would bloom into puffs of salt crystals. The recipe called specifically for non-iodized salt. Since most readily-available table salt by then was iodized, a person really had to go out of his or her way to find the non-iodized variety, so I assumed there was a reason the recipe called for it. My experiment involved growing two salt gardens--one iodized and one non-iodized--whereby I discovered that non-iodized salt made no difference except for the challenge of finding a supermarket that carried it.

The even bigger challenge of that experiment involved obtaining another vital ingredient: liquid bluing. Liquid bluing is a colloidal suspension of blue iron powder (ferric hexacyanoferrate) in water, and it was already a rarity in 1979. When I finally tracked some down at a tiny, dimly lit, locally-owned grocery store across town, I became a hoarder: I needed a mere four tablespoons, but I bought two 8-oz. bottles, figuring I might never again have access to this relic of olden-days laundry whitening.

Over the intervening 33 years, every time I moved, I took my two precious bottles of liquid bluing with me, from Urbana to Tucson to Corvallis to Madison to Lawrence and finally to Durham. In Durham, the bottles remained undisturbed for twelve years in a plastic bag in a storage cabinet, until, during a recent cleaning frenzy, I rediscovered them and decided I had guarded them carefully for long enough. It was time to play.

E and I accumulated the other ingredients and on Sunday afternoon, we mixed everything together and started our garden.

Here's what it looked like on Sunday:

And here's what it looked like this morning:

Notice the crystals hanging over the edge of the bowl. They completed their escape this afternoon, and I expect to find them making their way off the countertop later this week.

Happily, we still have nearly two bottles of bluing left, so E can share this experience with his own kid(s) 33 years from now (by which time he will also be conducting an experiment on the stability of ferric hexacyanoferrate suspensions).

Here's the recipe:

4 T salt
4 T liquid bluing
4 T H2O
1 T ammonia

Mix together and distribute over cut up pieces of sponge. For colored crystals, dribble drops of food coloring on the sponges before adding the salt solution.