galvanise body panels

[Shedendman]

I'm fixing up a tranny MK6 i though the MK5 was bad for rust,blimey
Anyway,done the drivers side sill and wheel arch ordered the panels in from where i normally go they now turn up galvanised,but these were shiny,so no probs,cleaned off welded on no probs.
On the near side told the owner to ordered some,but the next lot turned up dull galv not shiny,cleaned off where i need to weld but was a b*&$* spitting and sputtering,got it done in the end
SO
Is there a difference between shiny galv and the dull galv?

Let you mod gods put this in the right place if needed

 

[gordon stephenson]

I have had something similar welding galvanised gas bottle. Ground off galv but still horrible and spitting etc. Turned out the metal was pitted and grinding off the gala surface still left galv in all the pits.

 

[Shedendman]

These are brand new replacement panels,all galv,but after cleaning the gavl off i find the dull ones spit/spat the most

 

[Rocketman]

The actually visual difference with respect to shinny and dull galv falls into 2 categories

Firstly
http://www.redrivergalvanizing.com/faq.html#7
Extract -
"Why does some material appear shinny while others appear dull?
Differing surface appearances are almost always explained with either steel chemistry or steel thickness. Levels of silicon and phosphorus high enough to be termed "reactive" will produce a coating that will be significantly thicker, and as a result, much duller in appearance. Secondly, thicker steels will also develop thicker alloying layers of zinc. This thicker coating will also exhibit a duller appearance, however, unlike reactive steels, the thicker coating resulting from thicker steel (view thickness chart for more info) will not chip and flake off as is the case with reactivity. "

Secondly
Obviously beyond this it could have been more shinny originally but it is doing it's job which results in the layer dulling over time. Basically a oxidization layer.

 

[Wendelspanswick]

These are brand new replacement panels,all galv,but after cleaning the gavl off i find the dull ones spit/spat the most

Did you actually grind through to the bare metal or did it just look like that as you had only ground off the dull zinc, the colour change between the base metal and the galvanised coating is quite small.

 

[zx9]

Is one galvanised and the other pressed from Zintec or similar?

Edit: SP

 

[Shedendman]

Is one galvanised and the other pressed from Zintec or similar?

Edit: SP

You may have a point there,that didnt enter my head