A whitish coating, blackish spots and an unpleasant odour are the main signs of mould on leather. Usually, incorrect storage is to blame. 

Leather should be stored at room temperature and at a humidity of 40-60%. Lack of ventilation and excess humidity will encourage growth of fungi and bacteria in the leather. It also doesn’t help that the pH of leather provides an ideal environment for mould to thrive. While changing the pH of the leather would prevent mould, it would also damage it or allow it to age faster. 

Mould on leather clothing 

Mould occurs on both the surface and the inside of leather. Just cleaning the surface will not be enough to remove the spores, as some would have grown inside the material. We recommend treating leather garments with LEDER FEIN Leather Fixative to kill the mildew before washing them with LEDER FEIN Leather & Fur Wash Concentrate which will remove the bad smell, unless the mould has been sitting in the garment for too long and the smell cannot be completely removed.

Mould in leather car upholstery and leather furniture

The following instruction is for pigmented leather (colour finish on the surface). For other types of leather, always contact a specialist first. In particular, porous leather (suede, nubuck and aniline leather) must be treated cautiously! 

Mould that emerges after a few months of being stored in humid conditions is usually removed with diligent cleaning. Whether mould can be eliminated just by cleaning it, or whether a replacement of the cushioning material is needed, there is no simple answer. It all depends on how long the leather has been exposed to the unfavourable environmental conditions that allowed the mould to appear. Visible mould can usually still be removed, but the mouldy smell will remain the main problem.

Spraying with air fresheners won’t solve the problem – it will just create a perfumed smell suffused with mildew. Such severe cases can only be solved by completely replacing the upholstery and the leather. The cushion core or foam in this case cannot be washed or recycled. Since the leather has to be removed to replace it, putting in a new cushion core won’t cost much, and will also improve the seating comfort significantly. Another argument for new upholstery is also the health aspect; inhaling the mould spores can affect the health of children and people with weak immune systems.

 

                                                     Porsche mouldy leather seats    Porsche mouldy leather seats after treatment

How to clean mould in leather

Lighter mould growth can be cleaned away. We recommend the following process. Firstly, clean all surfaces thoroughly with Colourlock Strong Leather Cleaner. Most of the spores will be inside the item, so clean all visible areas, including frame, legs, side panels, etc. As always with leather, be careful not to wet the area too much.

The best product for general cleaning of mould is vinegar essence. Isopropyl alcohol also works well to remove mould, but cannot be used in leather as the alcohol dissolves the colour layer of the surface. On the other hand, vinegar is ideal as it will not only clean the mould away, but it will nourish the leather. Mix equal parts of vinegar essence (with 25% acetic acid) and water, and apply to all surfaces.

The cleaning process should take the mouldy smell away too. To check this, place your leather item under the sun with the windows closed, or use a hair dryer to see if you notice the smell. Repeat the cleaning process until the smell is gone. Try to find the source of the smell within the leather item and treat it with Colourlock Odour Remover  in addition to cleaning.

Aftercare of the leather is important to prevent mould from re-growing. Use  only synthetic products like Colourlock Leather Protector and Colourlock Elephant Leather Preserver which are based on synthetic oils and fats to ensure long lasting conservation without increasing the risk of mould. Using care products with animal or vegetable fats would provide the perfect breeding ground for infestation.

We recommend using Colourlock Leather Protector for matt leather. It contains oils to keep the leather soft and antioxidants to reduce its degradation. Alternatively, the Colourlock Elephant Leather Preserver is ideal for gloss leather, as well as for leather items that will be stored in humid areas, like a shed. This is a wax so it stays on the surface, therefore protecting it better from mould growth. It is better to apply these products lightly on a regular basis, rather than intensive treatments.

Colourlock Mould Leather Cleaning Process

Types of mould found in leather

Black mould sits in the material, unlike white mould which stays on the material. Just cleaning will not work.

When mould is white and hasn’t been on the leather for long, the chances of a successful cleaning are relatively good. In the case shown in the photographs, the car had been parked in a garage with no ventilation which resulted in an increase in the humidity levels. The time spent in bad storage was no more than 5 months. The mould had appeared on all soft surfaces including the soft paint of the plastic parts. Cleaning it was hard work, but not complicated. The smell of mould was not strong and no longer perceptible after the cleaning process.

                                                       Black mouldy leather    White mould in leather

Caution, not all whitish coating on the leather surface is mould. A well-known phenomenon that is visually very similar, to white mould is fat marks. This is whitish excess fat rising onto the leather surface. This appearance is often confused with mould. You need to identify whether it’s mould or fat before any treatment. The main indicator of fat is that careful heating of the leather surface with a hairdryer will make it disappear (because the fat melts) - which is not the case with mould. We will explain this issue further at a later stage.

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Top Tips!

  • It is important not to store leather clothing in a bag or in a humid environment without air circulation as this will increase the chances of mould appearing on the leather.
  • Clean the surrounding areas as well as the areas visibly affected by the mould growth.