Sheet metal

Thanks guys, it gives me a bit to think about. With the Zinc would it need to be primed both sides when used? i recall an AEC bus being re-paneled with zinc sheets and having rust come through within a few years.

The problem with stuff like zinc is that when you scratch, cut, dril, etc you automatically destroy the integrity of the coating so need to apply some secondary coating. Also the electrlysis process coes into play i.e. disimiler metals create current flow and corrosion.

zincaneal around 1mm thick is the easy to work but needs to be coated both sides because of the heat effected zone will affect the coating and the metal will want to rust quickly Cheers Gearbox

iff you a making a new tool box or head board ect using gal or zinkalume all good and use a acid based etch primer youwill have no problems NEVER USE ACID BASED ETCH OR NORMAL ETCH OVER BODY FILLER AS IT WILL FRY THE SAME AS PAINT STRIPPER with older technoligy i would use panel steel 16 gauge main reason being the molecular structure is different the newer products have alloys and additaves so when welding you have different expansion and contraction rates and the end resault is a lot of warping [lots more filler ] and if your old school panelbeater its nerry hard to heat and beat or shrink and nearly impossable to file finish or lead load pre 1970 car panels are acceptable as they have good quality steel you can use a spray on zink before assembly and welding as the zink is heated by welding it turns into a form of gal that will reduce or eliminate corrosion in those hard to get places with late model cars the alloys and zink panels are nearly impossable to repair thats why they toss them away or fill them with large quantaties of filler when you panel beat new cars acouple of educuated hits with a panel hammer and the metal actually gets harder and stretches add some heat to beat and a couple of taps later the metal is verry thin i would buy a sheet of panel steel its sutch lovely material to work with just my two cents worth 38 years of banging metal and bending spanners all the best don

There are, or have been, at least 4 different "gauge" sizes in use over the last several hundred years.
No-one even knows when "gauge" sizes were first used, but it was before the 1700's.
Originally, "gauge" size was for measuring wire diameter. However, later on in the 1800's, when thin sheet plate started to be produced, the wire "gauge" sizes were applied to sheet plate.

Wire gauge (see types) .. en.wikipedia.org/wiki/Wire_gauge

16 gauge corresponds roughly to 1.6mm. 14 gauge is approximately equivalent to 2.00mm. Below is a good little online converter, that gives gauge conversions to metric.
Here in Australia, we mostly used the British (Birmingham) gauge measuring system (S.W.G.) .. but if the item is of American origin, it will have been produced using the American gauge system (A.W.G.).

Online gauge conversion .. www.onlineconversion.com/gauge_wire.htm

During WW2, there were some serious hassles when it was decided to manufacture some American items of equipment here, such as LeTourneau earthmoving items.
The steel produced by BHP was produced to British/Australian standards .. but the American plans were written up to USS American steel standards.

Very few of the sizes in these two different steel measuring/production systems corresponded, so all the American blueprints for Australian manufacture, had to be re-written, to match Australian BHP steel sizes.

The cars of the 40's to 70's used mild steel in panels, which is relatively easily worked. You can't appreciably harden or heat treat most mild steel.
However, in the 80's, car and truck manufacturers started to use high-tensile alloy steel plate for body construction.
This is because HT steel is stronger, with a higher tensile strength, and manufacturers can use thinner steel for the same strength .. thus leading to serious weight savings.
It has been reported that 140 kgs of weight has been shaved off the weight of an average car, between 1960 and today.
Alloy steel is a bastard to work with, because it is easily heat treated by heating and quick cooling. In addition, the higher grade the steel, the more quickly it corrodes.

That's the reason why most older vehicles made from mild steel often have little rust .. but new ones are rusted out after a few years.
Of course, having thicker panels in older vehicles also helps, because a thicker panel can rust a little, and you still have metal left. With a thin, HT panel, any corrosion will soon perforate it.

Zinc coated sheeting should be sanded back to bare metal in the weld area, if you're doing arc welding. Zinc in the weld structure makes for a poorer-quality weld.
Zincalume is a proprietary coating combination of aluminium and zinc, designed for roofing, and produced by BHP, who originally had a patent on it.
It's terrible stuff to work with, it won't take solder unless its hydrochloric acid-treated, and even at that, its still difficult to work with.

Zinc anneal plate should be cleaned after welding, and a primer applied, as the heat from welding ruins the zinc coating, and therefore the protection.

You will find that most panel repairs by body repair shops, where panels have been stitch-welded in, will always start to rust where the welds are, because they don't bother to clean and coat the welds with primer.

Of course, it's often virtually impossible to apply primer to welds, if the panel is an enclosed panel, and you can't get at the welds on the inside, when you've finished stitch-welding the panel.