Rust stains are one of the most difficult marks to remove from stone paving slabs. They’re generally caused by metal objects – furniture, firepits, BBQ’s, garden tools, pots and parasol stands are common culprits. Contact with water washes deposits of iron particles onto the pavers which then leave a rust stain. Some weed killers also contain ferric sulphate which can cause rust stains.
As well as marks from external sources, discolouration can appear naturally within hard ferrous-type stone pavers, including sandstone, slate and granite. These stones naturally contain iron which can oxidise or rust when it comes into contact with moisture, from rain, washing with excessive amounts of water – for example, with a jet wash or patio cleaner – and from contact with some cleaning products. In addition, certain acidic cleaners, like brick acid and cement removers, also contain ingredients that can stain/damage limestone and sandstone pavers, and can accelerate oxidisation in hard ferrous stone. Ironically, these same products are often used to remove rust marks and can create an even greater problem. So, it’s really important to use the correct rust remover.
For safe removal of rust, we recommend one of two products, depending on the stone type and the nature of the stain – LTP Rust Stain Remover and LTP Ferrex. Both treatments can also be used indoors.
LTP Rust Stain Remover is a non-caustic solution that removes marks caused by external sources – like furniture and firepits. It is safe to use on all polished and unpolished natural and artificial stone tiles. After applying, the reaction between the rust stain and the treatment causes it to turn purple, so you can clearly see the product working. More stubborn stains may need more than one treatment. If this is the case, we recommend leaving 15 minutes after the first dosing, then removing the rust residue with a sponge or water and repeating until all of the ‘purpling’ has stopped. Once there is no colour reaction, all of the iron has been removed.
Here’s a link to more information, including a Video Aid which shows the treatment being applied, step by step.
LTP Rust Stain Remover – directions for use
- Ensure that the surface to be treated is completely free from dust and dirt before application. If necessary, first wash the pavers with LTP Power Stripper diluted 1:10 with water.
- SHAKE WELL BEFORE USE. Do not dilute. Completely cover the rust stain with the product. Leave to act for 15 minutes. The product colour will change to a deep purple as it reacts with the rust. Once the indicated time has elapsed, remove the residue and rinse the surface thoroughly with plenty of water and leave to dry. Repeat application until the stain is completely removed.
LTP Ferrex is a professional product designed to remove the naturally occurring particles of iron from within acid-resistant hard ferrous stone. Ferrex is an acid-based cleaner but it's the right kind of acid for harder stones. It is, however, not suitable for use on softer limestones, marble or pavers with a highly polished finish. It’s worth diluting the product with water before use and testing it at different strengths on a spot clean basis; in this way, you can establish the best dilution for your tile before general application. Here’s a link for more information on application and dilutions. Treatment to remove the iron can take between 3-6 hours. The reaction won’t be visible like LTP Rust Stain Remover; the treatment should be left to work and no agitation is generally needed. Once the staining has disappeared, rinse well with water and leave the pavers to dry.
LTP Ferrex – directions for use
- After testing on a small area, apply the solution to the surface and spread out evenly. For external applications garden sprayers can be used.
- For severe staining, surfaces should be agitated using a short haired scrubbing brush or black emulsifying pad.
- After 3 – 6 hours, rinse with plenty of clean water. If traces remain after a couple of days, repeat the process.
- After treatment, we recommend that the surface is protected from water with an impregnating sealer like LTP External Stone Sealer or LTP Mattstone H20. This will greatly reduce the risk of rust discolouration returning.
Some natural stones will appear darker after treatment, as the product continues to work following the initial application. This is normal and the darkening effect will gradually subside.
For more advice, visit our blog section on the website or https://www.ltp-online.co.uk. To contact the LTP team direct, call 01823 666213 or email [email protected]
