We receive a lot of questions about weatherproof steel. The answers to these questions below will increase your general knowledge of weathering steel. This means that when you are considering using steel for edging, retaining walls or elements as part of a garden landscape, you are better informed about what works best.
FAQ-hotlisten
- Are weatherproof steel and corten steel the same?
- Every time I install steel moldings in my garden, they rust away within a few years. Won't that happen to your edges too?
- How long will it last if it rusts? What would its lifespan be?
- I love this orange color (points to a bright garden border). Can I buy this straight away?
- Will it stain my pavers if it rusts, I've seen it happen with steel?
- I would like to weld a gutter to a water feature, is Weathering Steel suitable for this?
- I saw a friend's steel edge chipping, but he said it was weathering steel. Should it happen?
1. Are weathering steel and corten steel the same?
COR-TEN (or simply Corten) is the brand name for a steel also called Weathering Steel. COR refers to corrosive resistance, while TEN refers to high tensile strength.
The recipe of the alloys prescribed for Corten steel or Corten steel, whatever you want to call it, is what gives this steel the unique properties it has.
Weathering Steel was originally designed for railroad cars in the 1930s, but quickly became popular for bridges and other large outdoor structures for its appearance and to eliminate the need for paint; instead, they had a stable layer of rust on the surface that had been weathered by time. This was much easier than painting a bridge and having to start over on the other side when you were done!
2. Every time I install steel moldings in my garden, they rust away within a few years. Won't that also happen to your weathering steel edges?
Steel garden ornaments are often made from thin steel because it is easy to cut and therefore can have more intricate details. Simply put, steel isn't designed to exist outside in the elements, and once it starts to rust, it can rust away quite quickly. The question you can ask when buying such ornaments is whether they are made of corten steel and if not, look at the thickness of the actual steel used. 3-5mm mild steel will also last quite a long time in any garden, regardless of conditions.
As for why the weatherproof steel used as garden edging lasts longer, the simple difference is that the weatherproof steel is designed to become stronger through exposure to the atmosphere. In any case, you ensure that it is structurally healthy for at least 10 years. How this works, keep reading…
Nice garden decorations don't last long.
3. How will it last if it rusts away? What would its lifespan be?
Rusting away is exactly what does not happen with Weatherproof Steel. Due to its chemical composition, Corten steel exhibits increased resistance to atmospheric corrosion compared to other steel types. The steel actually rusts on the surface, forming a protective layer we call 'patina' (because we're nice!).
The corrosion-inhibiting effect of the patina is due to the special distribution and concentration of alloying elements in it. The patina continuously develops and regenerates when exposed to the elements to maintain a protective coat.
Another way to say this is by comparison. Normal steel develops rust that is porous with tiny pores in the surface that the eye cannot see. This rust does not seal the steel surface, so the rust process never stops and therefore has a tendency to flake off. While with weatherproof steel the patina produced is much less porous.
The rust patina is created under conditions of alternating wetting and drying. To ensure that a stable patina is created, this natural cycle is crucial and the process should never be rushed with salts or acids. The rust occurs on surfaces where oxygen is freely available. This means that rust develops very slowly in the soil due to low oxygen availability. Buried, weathering steel offers no advantage over mild steel.
As far as the lifespan of Weathering Steel garden edging is concerned, local conditions such as humidity, salinity (salt content of the soil), acidity (acidity of the soil), soil density (oxygen availability) and sulfur content will influence this. Proximity to salt water is another factor that accelerates oxidation. Under ideal conditions, the weather-resistant steel used in garden edging will last for decades (perhaps even 100 years!), and under poor conditions you can expect at least 10 years.
As an additional tip, you can also improve the life of your cut by painting the back or applying bitumen before filling it, when using larger steel panels for retention.
4. I love this orange color (points to a bright garden border). Can I buy this straight away?
The color of Weathering Steel changes over time due to the elements. We've explained why this happens: it's an evolving look!
When you buy it, it probably won't be rusted beforehand. When it is in your garden, it will gradually change from orange, maroon, brown to almost black over the years.
The Weathering Steel borders in the Show Gardens are generally in their early stages so they can have a unique vibrancy and brightness.
It is possible to fix the rust color at a certain point by applying a sealer coat when you are most satisfied with the color achieved. What you choose depends on your personal preference, but yes, it is possible. Please note that recoating may be necessary depending on the coating used and your local conditions.
5. Will it stain my pavers if they rust, which I have seen happen with Steel?
I've seen it too and agree it doesn't look good. The worst cases involve mild steel because of the way it continues to rust. With weathered steel, this should only be done when you are first developing a patina or if you are artificially rushing to achieve the desired patina.
Regular misting or using a damp cloth to wet the steel without runoff is one way to prevent this. If it is a sensitive installation on top of pavers and that is not possible, you can allow the edges to rust before installation to create a stable patina early on. We know of a recipe that we have used for show gardens that creates a stable patina in a way that is non-damaging to the steel itself.
Alternatively, you can simply move the edge slightly back from the cobblestones – perhaps fill it with flagstones? – so that the minimal runoff can spread harmlessly. If you wish later, you can even replace the stones when the patina has fully developed.
Once the patina is fully established, you can be assured that no nasty stains will form with Weatherproof Steel.
6. I would like to weld a gutter to a water feature, is Weerstaal suitable for this?
Welding weathering steel is not recommended due to the high phosphorus content of weathering steel. This means that the chance of cracks on/in the weld is greater. Any structural welding work is best carried out with Corten welding wire (when using MIG or TIG welding), but to our knowledge there are currently no Corten rods available for welding.
As an alternative to using rods, stainless steel welding rods can be used. However, these bars have a very high nickel content and the welds will not rust, creating a clear weld that is even more visible on an otherwise rust-covered product. Welding with 'normal' steel bars should only be used if strength is not a problem due to the previously mentioned cracking effect.
The other concern is that the process of developing a stable patina depends on the wet and dry cycle. Constant moisture would compromise this patina formation, especially at the interfacial level where the water level fluctuates. This means that life expectancy is impossible to predict, but is seriously affected.
For steel water elements we recommend the use of ordinary mild steel. Because it rusts faster, we recommend using a minimum thickness of 4 mm. You can expect it to last up to 15 years.
7. My friend has a lawn barrier with steel edges. I noticed it was peeling, but he said it was Weather Steel. Should it happen?
This is something we've seen happen a few times, usually in situations where the level of the soil/lawn/compost or mulch has dropped, exposing steel that was previously in the ground. This part of the steel rim has not been able to develop an atmospheric patina and is normally rusted. A simple solution is to return the filling to the level it once was to slow the rusting process.
However, keep in mind that rust is 7x thicker than the original. 2mm of steel becomes 14mm of rust! This means that 0.3 mm of rust disappears in flakes of 2.1 mm thick. In short, it looks worse than it is. It won't go away (unless flakes break off) and will still have some strength, it's just crazy. As a lawn barrier, as in the photo shown, it still works fine.
What is also important to understand is that visibly rusted steel (possibly even flaking) can still develop and retain a patina and may already have one; and it will still give power to the edge. It also acts as a protective paint, so if you leave it there (don't remove it!) it will slow further rust.
So yes, it can happen, but he will have a big barrier in the coming years.
