CONCRETE & STONEWORK
WHAT CAUSES IRON BREAKOUT – AND HOW TO TREAT IT
‘ Iron breakout’ is a common cause of orange staining on paths and patios, and these marks can be difficult to remove. It’ s often assumed that they’ re caused by rusting or flaking metal objects, like BBQs, metal umbrella stands and garden furniture. As a result, they’ re generally treated with a basic brick and patio paving cleaner which is often acidic.
Here lies the problem. These cleaners won’ t remove naturallyoccurring rust stains and can actually accelerate orange discolouration in some natural stones. The cause – and therefore the appropriate treatment – is very different.
What causes naturally-occurring rust stains? Rust or orange-coloured discolouration can appear naturally within iron-rich natural stone pavers – and it’ s especially common in sandstone. These stones naturally contain iron which can oxidise or rust when it comes into contact with water and oxygen.
Staining often appears after laying and is easy to identify. Rather than forming a defined mark, the colour gradually develops across
the surface, creating a widespread orange or brown bloom.
What causes rust spots and rust stains? In contrast, surface rust stains from objects often mirror the exact shape and position of the rusting metal that was sitting on the surface. Some weed killers and lawn fertilisers can also create rust stains; this is caused by iron compounds, like ferric sulphate, and these stains typically appear as small spots of rust.
Once you’ ve established which type of rust stain you’ re dealing with, removal can be swift and effective, provided that you use the correct product.
A case in point We were recently contacted by a customer regarding widespread orange staining on natural grey sandstone. The pavers had a relatively smooth non-slip finish. A hydrochloric-acid based wash had been used to remove dirt and light staining. It was applied following the manufacturer’ s instructions. A few days later, widespread orange / brown staining appeared across multiple slabs.
Our ECOPROTEC Rust Stain Remover was recommended by a local paving supplier. This remover is non-caustic and non-acidic and is particularly suited to natural stone. It is highly effective at removing surface rust stains, but it is not formulated to treat naturallyoccurring iron oxidation within the stone.
Initially, the treated area looked much better but, after approximately one week, the orange staining gradually reappeared. The treatment was then repeated two weeks later. Once again, the pavers appeared significantly improved immediately after treatment. However, within a few weeks, some of the orange staining had returned.
46 www. landud. co. uk Follow us @ ludmagazine