Galvanized hardware cloth rust proof?

[bridgetchicken]

Is galvanized hardware cloth rust proof? I will paint it with black rustoleum paint. But if they get wet, will they rust?

 

[SandyRiverChick]

It's a good question. I can tell you that areas and things where I have had galvanized hardware cloth (some painted, some not,) for 20years, has no rust.

 

[bridgetchicken]

Is galvanized metal the same as stainless steel?

 

[FunClucks]

Is galvanized hardware cloth rust proof? I will paint it with black rustoleum paint. But if they get wet, will they rust?

If I were you, I wouldn't paint it. You can if you want to, but that would minimize the protective effect of the galvanized coating on the steel. You want the moisture in the air to react with the zinc and therefore not with the steel underneath (which would create rust). If you paint it, the moisture can't get to the zinc well, there would be pinholes in the paint, and small areas where the paint doesn't cover. There would only be a small amount of zinc available to protect the steel because the rest was painted, and corrosion in pinholes is much faster than on unenclosed surfaces. If you paint it your cloth will fail faster than if you don't. Still may take a number of years.

 

[FunClucks]

Is galvanized metal the same as stainless steel?

Not at all. Galvanized hardware cloth is carbon steel or low alloy steel that has been welded together and then hot dip galvanized with zinc. This means they dip the mesh into a big pool of molten zinc. When the mesh comes out, the zinc cools onto it, forming a coating. The zinc reacts with the moisture and oxygen in the air, forming an oxide coating, preferentially reacting with oxygen to protect the steel from rusting. When you run out of zinc metal to react with, then the oxygen/moisture starts attacking the steel. But this is on a molecular level, so there is a lot of zinc that the moisture/oxygen has to get through first before it can rust the steel. Galvanization is a much cheaper process than stainless steel production.

Electroplated hardware cloth, where the zinc is applied via electroplating instead of hot dip galvanization, is not as robust of a protection. The zinc isn't as thick or uniformly applied to the steel mesh, so it does not protect the steel as long as it would if you had hot dip galvanized it.

Stainless steel is something like 304 or 316 alloy stainless steel, it has chromium and other additives in it that alloy with the steel and help protect it from corrosion. 316 provides better protection than 304 stainless steel, but is also more expensive. You can't see it, but a thin oxide film forms from the chromium in the steel and this protects the steel from oxidizing. If you heat the stainless steel up too high in the oven, especially for 304, or you use high acid foods in low quality stainless steel where they used less alloying elements, less Chromium, etc, then you will see pitting corrosion or corrosion at the grain boundaries. This is because the chromium either moves to the grain boundaries instead of being spread throughout the material (it got to hot), or the steel was not well alloyed (pitting corrosion due to high acid foods for a long time). These are indicators that you have poor quality stainless steel, and need to either purchase a higher quality metal or change what you're doing with it (remove the acid foods, keep it clean and dry, don't heat it so hot, etc.) Turkey fryer stockpots sold as a kit on Amazon often experience pitting corrosion soon after purchase due to poor alloying of the "stainless steel" in the pots, and possibly poor manufacturing/poor welding of the bottoms to the sides. These pits will eventually turn into holes. Not good for a container meant to cook over open fire using several pounds of hot oil.

Zinc has a lower melting point than Chromium, and is toxic to animals and people in too high of a concentration, and tends to rub off on things that touch it, so fencing is a good choice for this material. Cookware is not. Always wash your hands after handling galvanized zinc anything if you do it without gloves, especially prior to eating.

Stainless steel is significantly more expensive to produce than galvanized steel. Just compare something like fence latches. Galvanized is cheaper than stainless steel in all cases. Painted carbon steel cost is usually in the middle. Galvanized fence latches provide better protection from rusting, but don't look as pretty as painted ones. Stainless look great and have the best protection from rusting, but are more expensive to produce. Hence the price difference.

 

[Ridgerunner]

@FunClucks Wondering where you picked up your knowledge. I'm not trying to pick a fight, just wondering about your perspective. Your experience sounds different from mine. I have zero experience with stainless steel by the way.

I worked in design, construction, and maintenance of the offshore platforms. The splash zone, the area just above the still water level where the waves splashed, are extremely corrosive both because of them staying wet and the salty conditions. We found we could get extended life out of galvanized steel components like handrails and grating if we painted it. When we did a repair on grating, where it was tack welded on was painted. The difference in how fast grating corroded where the overspray coated it versus just grating was dramatic. We got with the scientists and it wasn't long before we were painting all of the galvanized steel on the platform, not just in the splash zone.

I totally agree about the pinholes in the paint, we called them holidays. A pinhole concentrates the corrosion. We tested for holidays in the paint. If any were found it called for repair painting. Pinholes or scratches exposing the bare steel underneath are not good in paint or galvanizing.

The way we could put unpainted steel structures in the salty ocean without them rusting away underwater was to use anodes. We would attach blocks of zinc to the steel so they were electronically connected. A current could flow between the zinc and steel. Since the zinc was more reactive than the steel the zinc would sacrifice itself to protect the steel. As long as we replaced those zinc anodes when they were getting used up the steel could last for many decades. You have a sacrificial anode in your water heater. Many bridges and buried pipelines are protected by anodes. Ships hulls can be.

The zinc coating with galvanizing provides this type of protection, but if you can keep the zinc protected with paint you can go a lot longer before the zinc starts sacrificing itself to protect the steel.

Is galvanized hardware cloth rust proof? I will paint it with black rustoleum paint. But if they get wet, will they rust?

Eventually, but it could take years before they rust.

 

[FunClucks]

@FunClucks Wondering where you picked up your knowledge. I'm not trying to pick a fight, just wondering about your perspective. Your experience sounds different from mine. I have zero experience with stainless steel by the way.

I worked in design, construction, and maintenance of the offshore platforms. The splash zone, the area just above the still water level where the waves splashed, are extremely corrosive both because of them staying wet and the salty conditions. We found we could get extended life out of galvanized steel components like handrails and grating if we painted it. When we did a repair on grating, where it was tack welded on was painted. The difference in how fast grating corroded where the overspray coated it versus just grating was dramatic. We got with the scientists and it wasn't long before we were painting all of the galvanized steel on the platform, not just in the splash zone.

I totally agree about the pinholes in the paint, we called them holidays. A pinhole concentrates the corrosion. We tested for holidays in the paint. If any were found it called for repair painting. Pinholes or scratches exposing the bare steel underneath are not good in paint or galvanizing.

The way we could put unpainted steel structures in the salty ocean without them rusting away underwater was to use anodes. We would attach blocks of zinc to the steel so they were electronically connected. A current could flow between the zinc and steel. Since the zinc was more reactive than the steel the zinc would sacrifice itself to protect the steel. As long as we replaced those zinc anodes when they were getting used up the steel could last for many decades. You have a sacrificial anode in your water heater. Many bridges and buried pipelines are protected by anodes. Ships hulls can be.

The zinc coating with galvanizing provides this type of protection, but if you can keep the zinc protected with paint you can go a lot longer before the zinc starts sacrificing itself to protect the steel.


Eventually, but it could take years before they rust.

How interesting!!! Very cool. I haven't worked with galvanized steel much in a professional capacity, mainly stainless and carbon or low alloy steels that were ungalvanized. I did not know that about painting of galvanized steel, or if I did I had forgotten. I'll have to remember that next time I want to extend the life of my galvanized hardware cloth - if I could get a good continuous coat of paint on it (or maybe some powder coating, cause it's more flexible but I wonder about the cost and what's the application temperature?), I could probably bury that stuff and have it last even longer than it would just being hot dip galvanized. Of course, it would take years to see any difference, but still, neat idea!

In my experience, the galvanized hardware cloth is rough, with shadowed areas, especially at the joins, and I would think it would be hard to paint without pinholes, but I guess that would depend on your paint and your painting technique. You'd need a paint that could accommodate the bending and flexibility of the hardware cloth without developing cracks, and to make sure your fencing is good and dry at least before you paint. In my experience, Rustoleum is great for flat unmoving surfaces, or surfaces that move slightly like a shed, but I wasn't sure how well it would do for flexible hardware cloth. That was part of the basis of my advice to the poster.

Totally agree, if you paint it, make sure there's no pinholes, or those will concentrate galvanic corrosion. Went down the rabbit trail a bit on that answer when that was really the main point.

You asked about my experience - most recently I've been looking at corrosion under paint on aluminum substrates in a beach environment (among other things), but I once worked with high heat processes (2000F+) for material deposition that were operated inside large vacuum chambers that had water jackets on the outside for cooling, and the cooling water flow was as high pressure as we could get it without cavitation to try and keep the stainless steel chamber from melting. Starting out, the chamber was made from 304 Stainless steel. After six months to a year (I forget), the chamber had developed leaks due to pinhole corrosion that had started in the water jacket. We were using hard water directly from the municipal water supply, and between the calcium deposits, the chlorine in the water supply, the constant water flow, and the radiant heat inside the processing chamber, the alloying in the 304 stainless did not prevent corrosion. The chamber was remanufactured in 316 stainless and there were no problems going forward. I think we did more to treat the water after that also, but not terribly much. There's many different alloys of stainless steel, and they're all designed for different applications. Use the wrong material, and it can be a costly mistake to fix. www.mcmaster.com or grainger.com are fun to read because in the application pages they tell you the recommended applications for each of the steel alloys and other materials they sell.

And those folks who sell substandard stainless steel pots as turkey fryer pots? That's irresponsible and reckless. I don't even want to think of how many people have been hurt by that and I just know about it. The pictures on Amazon from folks who had used the pots and had them corrode so much at the bottom that oil was leaking out the pinholes were just scary.

 

[Sally PB]

Well, that was very interesting! Thank you, @FunClucks and @Ridgerunner, for sharing your knowledge.

 

[Shadrach]

Is galvanized hardware cloth rust proof? I will paint it with black rustoleum paint. But if they get wet, will they rust?

Yes, that's the point of the galvanizing.
Not all galvanizing is equal though.
However, it's a coating and beneath that is steel. So, it's more a question of how long the coating will last. One should get at least 20 years from a galvanized fence.

 

[aart]

We found we could get extended life out of galvanized steel components like handrails and grating if we painted it.

Does any paint stick well to galvanized?
IIRC you need something specific.