Diana Kulaga wrote:

A friend (and very good grower) uses that CLR cleaner stuff. I suspect


the "Lime-Away" brand would work just as well. I used to use acetic acid
at about 10% concentration. I don't know how this would work on thin
leaved orchids...

Hmm. I don't have any CLR around, but I just checked the bottle of
"Lime-Away". It contains sulfamic acid. Other rust products contain oxalic
acid, which is pretty strong. Does he dilute the CLR? Just curious



Not as far as I know... I've seen her spray it right out of the spray
bottle on the plants. You would get denaturation of surface proteins,
if the acid were strong enough, and maybe some other interesting
chemistry. But that is at the surface of the leaf. Thick leaved
orchids usually have a pretty thick waxy cuticle, so perhaps an
occasional acid wash wouldn't do much harm? I certainly wouldn't bathe
my plants in it every day...

Actually I think that while Lime-Away and CLR recommend gloves, they
aren't particularly dangerous to bare skin. As long as the contact is
brief and you rinse it off. Vinegar is something like 5% acetic acid,
and I spill that on myself all the time with no obvious effect.

Take it with a grain of salt. Don't blame me if you kill your cymbidium
with it. I'd bet good money that you couldn't hurt a standard cattleya
with battery acid, as long as you wiped it off right away. I can't
remember enough organic chemistry to know why I think oxalic or acetic
acids are less dangerous than sulphuric acid, but it seems to be
entrained somewhere in that grey sticky substance in my skull. Probably
as wrong as everything else in there.

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit