Which should I choose?
Both are excellent edging materials for edging with their flexibility, strength and durability but what are the differences ?
What is Corten steel?
Also known as Cor-Ten, it is a brand of weathering steel, in which the surface rust layer protects the steel beneath from further degradation, this gives Corten an increased life in comparison to mild steel. Our Corten steel edging will weather to brown in around a month depending on the conditions.
While Corten was initially designed for use in more industrial settings it became popular with architects and artists and from here it found its way into gardens.
Our Mild Steel edging
This will also form a rust layer and to some extent this too protects the steel below but degradation is faster. That said the process is still extremely slow, it’s hard to say exactly as the conditions play a big part but in a fairly aggressive situation degradation will be around 10 microns per year (0.01mm) taking roughly 50 years to degrade just 1mm! So even our 3mm thick mild steel edging has great longevity let alone our 6mm thick option!
Mild steel edging will take longer weather to brown in comparison to Corten, in average conditions this is around 10 months.
Do they look the same?
We are often asked for Corten edging as clients are looking for the weathered look for which the Corten brand has become synonymous. However both mild and Corten steel take on this patina. It would take a keen eye to tell the two apart once weathered.
Corten has a slightly lighter more orange appearance largely due to the copper content but both mild steel and Corten develop the lovely warm, varied brown tones.
Your edging will arrive largely un weathered, mild steel starts off slightly darker whereas Corten will be a bit more metallic and shiny.
Weathering times of both our mild steel and Corten edging can be reduced with one of the rust accelerators available online or simply a regular application of a salt, vinegar and water solution, or to accelerate even faster add Hydrogen peroxide (3% food grade is enough, available on Amazon).
We tend to be conservative with a weak solution using – 2 cups of peroxide, 4 tablespoons of vinegar and salt mixed in 2 litres of water. There is no need to go any stronger. This solution can be painted, wiped or sprayed on.
What about cost?
It may come as no surprise that our Corten edging is more expensive than mild steel, this is due in part to the higher cost of Corten but not many people realise that Corten is only produced in sheets and requires laser cutting to form the various edge sizes which add a cost element.
On average our Corten edging is around 65% more expensive than our mild steel edging.
Our opinion summarised
Corten does have more longevity, but unless your cladding a building or making sculptures from thin sheets, edging made from mild steel has a more than adequate service life.
You will need to wait a bit longer for mild steel to weather to brown.
Corten edging would be recommended if your looking to match in with existing Corten steel, where the edge is adjoining Corten raised beds or cladding for example. Or, and this is an important one, if your setting the edging on or above somewhere where rust staining below would an issue such as over light coloured paving. Staining is not an issue with, lawn, border, gravel or tarmac edging.
So for a majority of applications we would recommend mild steel edging as it more cost effective and does pretty much the same job. For areas where matching or staining are considerations then Corten edging is the way to go.
We hope you found this useful!
For more information on any of the above please get in touch. Dawn or Jimmy are ready to take your call.
Three facts about Corten steel you probably didn’t know…
• Corten steel was initially developed in the 1930s for railway wagons transporting coal.
• The rust will vary in colour depending on the situation, so Corten steel will take on a slightly different appearance inland compared to coastal areas or even in the same garden for example under trees.
• Most shipping containers are made from Corten steel.