Petromax HK250 restoration

The black spots are: rust, "blank" metal.
You will not get the shiny new look back with any treatment, I am afraid ;-)

There is also no easy, speedy, wonder stuff that gets an old lantern clean again. It's all to elbow spit and lame hands from polishing.
For electro plating the metal must be clean, spotless and it will not remove dents and/or pitting.

 

If they are rust as you say, why a rust remover or even better a rust converter (like tannic acid) will not stop the corrosion? My issue is not to make it shiny again. I understand that this is not possible anymore. My target is to stop or slow down corrosion. For example, tannic acid turns rusty metals to black. I have no problem with this. Let it be black. Will corrosion stop? Or prevented?

 

I have no experience with chemicals. But others may.

 

Fighting rust on heated parts is not easy. You can make that part clean and shiny by keeping long enough in strong citric acid solution and scaping with steel brush - it can be done. After that you have to use some heat proof rust prevention, because most of the plating will be gone. It can be painted with some heat resistant paint. I personally heat and quench such parts in oil to cover with (reportedly ) heat&rust resistant layers. I just prefer that dark, oldish look then new paint in old lamp - up to personal preferences. I am more into "repair" then "restore"
all the best,
Piotrek

 

Dear Antonis,

yes the tannic acid or other rust converter will stop that rust, but not for long. It will need protection just as a new piece of mild steel will too?

good advice from other members and hope you can hunt down a solution

p.s. there may be alternatives to using a battery charger? have a look online as some folks use plug in phone chargers as the power source or similar?
lots of help online with nickel plating too

 

Thanks @podbros but I do not think that plating will work, as the metal is not completely clean. Unless it is possible to fully clean it with what @Piotrek wrote, that is to keep it in strong citric acid solution, maybe for days, and then scrap with steel brush. If this is possible then maybe it is the best method for me. I was just reluctant to use string citric acid solution for long times fearing I will create more problems. As I wrote before I do not mind about the dark color. I only care to prevent rust.

Dear @Piotrek can you provide more details for your oil method? Thank you.