Oyster Sauce wrote: Wiring a branch does not penetrate the phloem or cambium as a screw or staple would. If there are any dangerous elements to copper (IF there are any) then the difference between wrapping and puncturing are obvious.

Seems unlikely as the copper wood needs to oxidize and the oxidized copper to get dissolved, then taken up by the roots as 'nutrient'.
So, doesn't seem that would happen.

However, why use copper if you have doubts about it ?

Auk wrote:

Oyster Sauce wrote: Wiring a branch does not penetrate the phloem or cambium as a screw or staple would. If there are any dangerous elements to copper (IF there are any) then the difference between wrapping and puncturing are obvious.

Seems unlikely as the copper wood needs to oxidize and the oxidized copper to get dissolved, then taken up by the roots as 'nutrient'.
So, doesn't seem that would happen.

Sounds logical.

Auk wrote: However, why use copper if you have doubts about it ?

I was hoping for a definitive answer for future use. Knowledge is never a bad thing and you never know what will be available on the day you have to make a choice.

Oyster Sauce wrote:

Auk wrote:

Oyster Sauce wrote: I was hoping for a definitive answer for future use. Knowledge is never a bad thing and you never know what will be available on the day you have to make a choice.

Stainless Steel.

The safe bet.

I was hoping for an answer to my question in the OP.

I gave you the answer. It does not matter.

leatherback wrote: I gave you the answer. It does not matter.

It does matter to me. I would like to know what metals are safe and (by default) what metals are not safe. The only thing we have established is that coper may not be unsafe and stainless is almost certainly safe. But the others? Aluminium, brass, zink? Depending upon the project, you need to know what materials are available on any given day and what ones are suitable. If you need tiny screws perhaps you can only find them in brass or maybe you need bevelled screw heads and they are only available in zink coated.

OK. Why ask if you do not want to hear that there is no problem?

Oyster Sauce wrote: stainless is almost certainly safe.
Depending upon the project, you need to know what materials are available on any given day and what ones are suitable

That sounds very random and it tells me you're doing it wrong.
If you're doing bonsai, you have the suitable materials available beforehand.

You do not decide suddenly on a certain day to do a graft and start looking around what you may have available at that moment.
You prepare, plan, and make sure you have the required materials available.

So, choose what you think is safe.

leatherback wrote: OK. Why ask if you do not want to hear that there is no problem?

Your reply was, "Just use whatever". It doesn't sound like a very earnest reply to me.