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Metallizing vs HDG? Which will give a better finish and rust protection?

2003

I am installing a spiral steel staircase outside my house on my back balcony. I have a direct, west facing (almost continual) breeze from the Pacific ocean which is a about three miles away.

I want a nice finished product that won't rust (and not cost a fortune, which rules out stainless steel). I first considered aluminum with a powder coating. But I have been told that it is softer than steel and will nick, and when the powder coating scratches the exposed aluminum could pit underneath and spread like an infection.

I next I considered steel with either a hot dip galvanizing finish etched and painted or just powder coating over the HDG. I read somewhere that there were finishing issues related to the smoothness of the finish from the HDG process and the bumps from the running that occurs in the coating as it comes out of the tank. Then when the powder coating is applied over the HDG it does not look good. Is that true? Assuming it was not the best option, I continued to look and found metallizing. I now am leaning toward metallizing (there is a company in my area who does this process). They sand blaster first then apply the zinc through the 'metallizing process.' The finish does appear consist (although not smooth, which is OK with me). They say I then need to apply primer (lots because it is absorbed by the metallizing) and then paint the stairs (they said with a polyurethane paint). They say it will protect the metal against rust even better and longer than HDG.

I don't know what to do. I don't need a perfect finish but I would like something attractive. I don't want it to rust and I will be walking up and down the stairs and I am sure nicking the paint and stairs over time (even if only slightly). For sure it will be constantly exposed to the salt air.

What should I do? From what I can tell the cost of HDG and then paint (I am assuming powder coating after HDG is not a good option, tell me if I am wrong) or the metallizing process and then painting (again I am assuming powder coating is not the best option after the metallizing) is about the same. I am not an expert in this area and have looked around the Internet but can't find much information.

I found this website through Google. If this is a settled issue sorry for the question. If it stirs some conversation I am glad to be involved.

Thanks in advance for any advice you have,

Robert Pack
- San Diego, California, USA