Galvanized nuts and bolts

[vincentt]

I have a lot of expander bolts outdoors on post bases. The surface is worn off due to post foot replacements and in some places, it has already started to rust. Can they be re-threaded again or smear on some rust protection paint?

 

[Staffans2000]

Can and can.
Cold galvanizing spray cans are available. But it naturally doesn't hold as well as hot-dip galvanizing.
From a durability standpoint, it will take a looooooong time before the bolt gets damaged.

 

[ricebridge]

Are you supposed to use the bolts? If so, smear copper paste on them and do it. Then the bolts will last for many years.

Aren't you supposed to use the bolts? Cut them off with an angle grinder.

 

[vincentt]

Are you supposed to use the bolts? If so, smear on copper paste and do it. Then the bolts will last for many years.

Are you not supposed to use the bolts? Cut them off with an angle grinder.

I'm going to attach post feet later, so they should be used. Copper paste sounds good, alternatives?

 

[Peter2400]

I will be putting on pole feet later, so they will be used Copper paste sounds good, alternatives?

Yes, if you want them shiny and nice again, zinc primer is probably the best choice.
https://www.paintpro.se/farg-ytbehandling/sprayfarg-sprayprodukter/zinkprimer

 

[mexitegel]

I don't think zinc paint/primer lasts very long before it looks like it did before you sprayed.

 

[prototypen]

It helps somewhat to attach new hot-dip galvanized nuts.

Protte

 

[vincentt]

It helps a bit to put new hot-dip galvanized nuts there.

Protte

Does it? It's the bolt itself that doesn't have any galvanization left...

 

[roli]

The zinc "wanders" between the different parts. If you screw a hot-dip galvanized nut onto an unprotected screw, the zinc on the nut also protects the parts of the screw that come into contact with the nut. So, putting a new nut increases the protection level of the screw compared to reusing the old nut.

This is what makes hot-dip galvanized items so resistant to rust. If you get a scratch on the zinc layer, the surrounding zinc protects the "exposed" surface, which a paint layer does not do.

 

[corre]

Put on a new nut, it provides some protection. Once you have tightened and adjusted everything, apply some pine tar for protection. Easy to remove with lacquer thinner the day you need to, and it protects well until then.

https://www.biltema.se/bilvard/bilunderhall/underhallsprodukter/tjarspray-2000018308

 

[hyggabus]

If I remember school chemistry correctly, the rule is that you can protect a metal by coating it with a less noble metal, as the less noble one will corrode before the one you're protecting. Iron is nobler than zinc, which is why the zinc protects the iron (steel).
For the same reason, you must insulate, for example, aluminum boats from stainless steel, otherwise the aluminum will corrode.
Copper, on the other hand, is nobler than iron, which is why it shouldn't be recommended - or am I remembering wrong?