[Ferro List] Passification of galvalume???

[Keith B]

Thanks Alan

I've had a description of such wire as looking like the "galvanizing" 
was brushed or sprayed on.  My experience is increasingly that Chinese 
finishes are for sales effect, not durability.  Their thin, bright and 
very smooth galvanize looks almost like chrome but it's not good for a 
year and too thin to measure - presumably electroplate.  Don't want that 
on equipment, let alone in contact with mortar. 

I wondered whether the 'rabbit wire' was coated to simulate heavy good 
galvanizing, or simply to give the impression of thickness.  Dipping at 
solidus with a partial melt might give the thickness, rough surface from 
unmelted powder, and a combination of viscosity, surface tension and 
solids to account for the corner bridging.  A feature of the photos Tom 
put up is the noticeable grid of pockets corresponding to wire 
crossings.  That's prima facie evidence that the lack of cure is 
directly proportionate to the coating thickness or mass, i.e. that the 
volume of mortar strongly affected was probably more proportional to 
local coating mass than area.  In turn, it would suggest that much more 
of the coating was involved than should have been for either conversion 
of an existing passivating surface or the formation of a calcium zincate 
one.  That loops back to a suspicion that an alloy or mix was used to 
produce a metal or metal/oxide/dross slurry at the zinc solidus.  If so, 
it's hard to guess the subsequent chemistry in the adjacent mortar.

kb

twobends at charter.net wrote:
> Hi KB,
>
>   Two years ago I purchased some chinese made rabbit barrier (only source in town), and it 
> was indeed very brittle and was bridging the corners excessively.  It spalled off so badly 
> most likely every outlet in town such as home depot, menards or  walmart must have gotten 
> some complaints on the poor quality.
>
>   This must have had an effect on the suppliers as at least one was stocking this 
> electroplated mesh the next summer.  NO brittleness or spalling.
> ...
>