Trouble is that aluminum does not break down in to aluminum sulfate. Aluminum sulfate is a completely different chemical compound and is commonly used to lower the Ph of soil.
http://en.wikipedia.org/wiki/Aluminium_sulfate
When aluminum breaks down it actually forms aluminum oxide, or andonizes, which actually protects the aluminum from further decomposition.
So, sounds to me like the reputable sources warning against the use of aluminum wire probably own stock in a copper mine.
Well now I feel like we are getting some stuff confused here... I don't recall saying that aluminum breaks down into aluminum sulphate or that the processes of wire being weathered or oxidized on our soil would be similar... In fact I think I said "Aluminum sulphate mixed into the soil is
obviously not the same thing as a little piece of wire tying the tree into the soil..." Obviously that Wasn't enough to clarify what the point of that story was, so I apologize for even bringing it up. My point was that Aluminum in various forms is harmful to plants, and I used that story more as a sarcastic way of illustrating how even people we assume to be reputable- like say... They guy at the nursery who told me to use the stuff- are sometimes wrong. I fully admit it may not be necessary to avoid using the wire in my soil, but there is at least enough evidence in the literature I have read to suggest it could be an issue so I personally chose to avoid it. Doesn't mean I think aluminum wire and Aluminum Sulphate are the exact same thing... Doesn't mean I am calling people out who do it or trying to start some Aluminum vs Copper war... I was simply responding with some info I have read and and put into practice myself to a poster who asked some questions about types and size of wire. But if we really want to get into Aluminum vs Aluminum sulphate and talk about the chemistry contained in the page your posted a link to (if you don't want to get into that, just skip the next couple paragraphs...)
Just to kick it on down the line a step further though... Since we seem to have generated a fund little scientific discussion about properties and com pounds and chemistry I suspect most people here barely understand- You provided a link to A Wiki page about Aluminum sulphate and I would like to ask... If The metal Aluminum (like say perhaps the stuff they make the wire out of) doesn't break down into Aluminum sulphate and they are two completely different chemical compounds... Why then can you MAKE ALUMINUM SULPHATE FROM HEATING ALUMINUM WITH SULPHURIC ACID?
As quoted from your link regarding the preparation of Aluminum Sulphate:
" by heating aluminum metal in a sulfuric acid solution:
2 Al(s) + 3 H2SO4 → Al2(SO4)3 + 3 H2 (g)"
Sounds to me like it absolutely DOES break down into Aluminum Sulphate... Perhaps only when the proper conditions or chemicals are applied... But it certainly does break down into that and they certainly are not COMPLETELY different compounds when Alumunum Sulphate's molecular formula (again, from your link)= Al2(SO4)3
Now I do not pretend to be a Chemist, but when two parts of Aluminum are present in a compound I don't call that compound something completely different from and whole unrelated to aluminum... A more complex form of it perhaps... And altered form... Sure... But to act as though the metal form of Aluminum has nothing to do with this compound is completely false according to the link you provided... Just saying.. For arguments sake.. To play devils advocate... To further the discussion... Because I like being the smartass... And because I felt there was some piling on being done here...
**Again, I wish I had never mentioned that little story about it because it has clearly caused a spiral away from the points at hand and I am seriously not even disagreeing with most the actual points relating to bonsai being made here... Just felt the need to follow up after reading over that link.
Now, we can certainly continue to argue the chemical composition of these elements and make hypotheses about the effects or likelihood of their occurrence within our Bonsai pots... Or we could try to get back on task and help the OP learn more about wire- which is HONESTLY all I ever intended to do in the first place!
To that end- I guess plenty of evidence has been provided that both copper and aluminum wire is generally fine to use.. If you are asking because you plan to purchase some wire in the near future- buy small sizes if you have small trees, larger sizes for bending larger branches, but I have found the small and medium sizes are used the most by me (and you get longer stands of wire for the same weight because they are thinner... Funny how that works out!): Copper is stronger and less prone to bouncing back once it is bent to shape. aluminum is a little softer I guess ( a relative term when dealing with metal against the bark of a tree- ALL metal is harder than wood!) and takes larger gauges to bend the same branches as smaller gauges of copper...
A good trick for determining how thick of a piece of wire you should use for a specific job- that Arthur Juror showed me one day when I was lucky enough to meet him- is to hold the wire with an inch or two extended from your finger tips, and press it against the branch you are trying to bend- if the branch bends as far as you need it to without bending the wire, you are good but if the wire bends instead of the branch you need to go larger! This seems like common sense in retrospect, but until he showed it to me that seemingly minor thing was always puzzling to me... And you will hear and read so many different "rules of thumb" about wire thickness vs branch thickness for copper vs Aluminum (the wire should be 1/3 the thickness of the branch...)- as JKL would say "poppycock"- just see if the wire will bend the darn branch and go from there!
I hope all of our ranting and raving and arguing over meaningless stuff none of us can prove has not clouded this thread to the point of being no help to the OP and I am sorry that my little comment about the potential for negative effects from Aluminum started such a silly off topic blow up... But I am happy to keep on blathering on about for a solid 2-3 more pages if anybody wants to go a couple more rounds!
I know from the roots but what are the mechanisms and how do they know "what" to "extract" or move. Fundamental questions to answer before moving to the extremes of sulfuric acid
