Welding and painting galvanised steel

[demented]

For a section of a car body, which is more prone to corrosion, so planning to use Galvanised steel.

I'm aware of the fumes given off when welding galvanised steel and the neccassary precaution will be taken.

However, I believe that galvanised steel is difficult for paint to adhere to ?

Also, can galvanised steel be welded to mild steel without issues, either during welding or at a later date?

I've read somewhere that some kind of reaction can occur causing severe corrosion to the mild steel and the weld due to the two metal types either fusing together during welding or just by contact ?

If such is true, it kinds of defeats the object of using galvanised steel ?

As for painting, on the finished product I intend to use seam sealer, body filler, possibly fibre glass bridging compound, underseal as well as acid etch primer, high build primer and base coat.

Will my existing compounds/products adhere to galvanised steel ?

I've never knowingly purchase a product which claimed to be suitable for use on galvanised steel.

The galvanise steel has already been laser cut to size and is 1mm thick, yet I've read elsewhere which states steel of this thickness is too thin for the galvanisation process ?

In the past I've use Zintec, which is some kind of zinc coated steel for car body repairs.*

Prior to welding, I've flatted the steel with 240g abrasive disc and once in final situ, prepared the Zintec for paint in the traditional manner and never experienced any issues with regard to the final paint lifting of flaking off or the seam sealer or under seal or any other paint product failing to adhere.

So, can anyone advise, especially with regards to painting galvanised steel.

 

[astro_al]

You are talking about electrolytic reaction. You're welding steel to steel, so don't worry about it.

You need to get the zinc off the area where you weld, use a flap disc or similar to clean back to bare steel. This has all been covered many times on the forum.

Use mordant solution on the galvanised part to prepare it for paint. Just follow the instructions. After that, use what you like.

Al.

 

[demented]

Thanks for the prompt reply stro_al

Due to additional cost of the Mordant solution, toxic fumes and a mask for a one off job, I've decided against the Galvanised steel.

I'm wondering whether to use 1.5mm Zintec?

Please offer you opinion and advice to my alternative thread:

"Can 1.5mm zintec be bent by hand ? "

 

[outofthefire]

We used to weld a lot of galv in my last job building wagons, the painters just used to go over it with a da sander then etch it and spray it as normal.