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Possible Domestic Use of Aluminum Swarf

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  • Possible Domestic Use of Aluminum Swarf

    I caught an article in the local paper by the botanical garden. It said the the hydrangea plant's flowers change between pink and blue depending on the amount of aluminum available in the soil. While the gardener was advised in the article to use aluminum sulphate to make the flowers blue, it can burn the plant: So, us machinists can probably help the gardeners around us turn their flowers blue by planting some aluminum swarf with the hydrangeas! This may help machinists with gardener wives justify the hobby.

    Regards all,

  • #2
    I read an article in a rather old (40s?) PopSci or PopMec that adding Woods Metal to soil helped increase yields in gardens.

    Styrofoam peanuts are good to mix into denser clay soils to lighten them up.


    • #3
      Aluminum doesn't contain sulfur. Won't do a thing. What will work is pouring out your used anodizing solution around the plants.

      Incidentally, it has always been my understanding that it is the pH of the soil that causes the change in color.
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      • #4
        Cameron, I saw that article too, but didn't read the details.
        But like Evan, I always thought the hydrangea's color was simply a reflection of the soil PH.

        I'll have to read that article this evening.


        • #5
          It does have something to do with Ph, and the aluminum sulphate certainly gives it to the plant!

          If I dont add it to the soil a couple times starting when the leaves begin to show, I'll have very pink flowers. I remember when I was a wee one (a LONG time ago!!) my Grandmother adding rusty nails to the soil to get a brilliant pink flower, she would also have the blues, but I dont remember/know what she would do to get them.
          Theres also a beautiful white availiable now, wonder if theres a metal additive to get that?
          If everything seems to be going well, you have obviously overlooked something........


          • #6
            FWIW, I'd heard similar results from burying steel swarf at the base of spruce to change the needle color from verdant green to blue?
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            • #7
              The article I read said that the dependence on pH is due to the difference in the solubility of aluminum ions as pH goes down.

              Aluminum sulphate is both a weak acid and source of aluminum ions whereas aluminum is just a source of aluminum ions. If the article is to be believed and aluminum ions are the source of the color, making the aluminum ions available without acidifying the soil too much might make a less damaging way of changing the color.


              • #8
                Bill Pace, several yrs. ago my wife found an old galvanized gas can, and cut the top partially out and used it for a planter. I think she planted rose moss and petunias in it over the yrs., and everything bloomed white, no color at all. Based on that, you might try zinc.


                • #9

                  I does depend on what you consider damaging. Our soil is around pH 9 so adding some acid is a Good Thing. That's why I suggested anodizing solution. It's chock full of aluminum that has dissolved in the sulphuric acid. Add some bicarbonate to take the edge off it and you will have a very strong solution of aluminum sulfate. It's so loaded that when if foams from the bicarb the bubbles look like aluminized mylar.
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                  • #10

                    The article I was reading noted that adding aluminum sulphate can damage the roots. Too much aluminum is apparently bad for plants in general said the article. The anodizing solution idea isn't too bad though.

                    I don't actually grow these things although my neighbor does, I just posted this as a cute way of getting a hypothetical SWMBO to be more forgiving of a shop



                    • #11
                      Hydrangea color

                      I've never heard of the aluminum version of this, but I've always used a table spoon of cast iron as fine as I happened to have.


                      • #12

                        Domestic uses?

                        Mice don't much like swarf...... it cuts their paws, and cuts other things if they chew it. Ditto for steel wool.

                        Stuff mouse holes, and the mice will not be back. Aluminum won't rust like steel wool.

                        Keep eye on ball.
                        Hashim Khan