I personally dont know of any online retailers that sell that diameter. After a quick Google search here is two sites I found selling that size wire(one sell aluminum the other copper). the only problem is their in the UK so shipping is going to be expensive.

http://www.willowbog-bonsai.co.uk/store/index.php?act=viewProd&productId=245

http://www.johnhanbybonsai.co.uk/store/index.php?act=viewProd&productId=51

Id recommend asking around at your local Bonsai club someone there might know. Sorry i dont but I never have had a need for that small a size so i wouldn't know where to get it.

Good luck
-Mike

I am going by my local Bonsai Shop this weekend. I will check for you.

Thanks. I wrote Dallas Bonsai same day as I posted, but they haven't bothered to reply to me.

Al

Al
It is so thin I'm wondering where and/or how you use it. I have been using 1 mm on fine branches and and it breaks very easy.
Paul

I use it for very fine wiring on small trees or detail wiring on well-ramified trees, and to wire fine juniper branches upward when building foliage pads. I've never broken a piece before unless I was reusing a piece (almost never do) I'd cut off & nicked with the wire cutters.

Al

I'm looking for it too but I'll just use a finer copper wire. I get mine from Jim Gremel at jimgremel.com. There's a lot to learn here. The equivalent of .5mm aluminium wire in copper is very fine.
If your wire breaks it's probably from china.

Al...

Try jewelry supplies. Aluminum wires are used for wrapping, bindings, etc. Either on-line searches, or go to a good magazine stand and look for jewelry craft/bead craft magazines. Ad sections are loaded with wire suppliers, and specialty tools.

Hope this might help you find what you might need.

Frank

Thanks, guys!

Al