Hardware cloth is made from relatively heavy steel wire that is laid up
in a square pattern (some versions are woven) and run through a
galvanizing (generally molten zinc) bath to both bond the wires together
and give some corrosion resistance. I checked the 8, 4, and 3 per inch
hardware cloth I have and the wires are 0.47, 0.64, and 0.80 mm diameter
respectively. Yes, the material corrodes over time, but I have had some
in continuous service for over six years and it is discolored but still
intact - even when spanning over 12 inches (30 cm) in the bottom of a
grow box.

I have also not found the zinc galvanizing to stop root growth. They
grow right through it when they are filling the bottom of the pot. I
have even seen roots grow so they enclose the wires when I am letting
them grow into the ground to get a big thick trunk.

I like to use the 4 per inch hardware cloth for most pots since I have
rarely seen it clog roots or soil fines between repottings. I have seen
clogging in both 8 per inch hardware cloth, plastic hobby mesh, and
particularly window screen (approximately 16 wires per inch). However,
I do use the 8 wires per inch hardware cloth for trees where I am using
a finer soil - they are further along the path. I know there are people
who use all three of the things I don't like very successfully -
different soils, watering, repotting, etc. all contribute to this.

Marty

************************************************** ******************************
++++Sponsored, in part, by Evergreen Gardenworks++++
************************************************** ******************************
-- The IBC HOME PAGE & FAQ: http://www.internetbonsaiclub.org/ --
+++++ Questions? Help? e-mail +++++