Phenolic Yellowing of Clothing During Storage - Causes and Solutions

We may have experienced that some challenges are there in the storage of white and pastel coloured textiles. Many factories facing the same to keep the colour fixed of white and pastel coloured clothing during storage. But at some point, they fail to keep, as the products turning yellow, known as Phenolic Yellowing and is a common occurrence. It is usually happened due to various chemical and environmental factors.

What is Phenolic Yellowing?

Phenolic Yellowing is the yellowness on textiles or discolouration of textiles caused by the action of oxides of nitrogen (NOx) on yellowable phenols, observed on white or pastel coloured textiles.

Basically, yellowing or discolouring may possible in all textiles and all colours, but it is specially visible in the very light colours like white and pastel shades. In case of darker shades you can only see the colour getting a bit faded.

What are the conditions that cause phenolic yellowing?

Out of the number of conditions that causes phenolic yellowing from finishing to packaging and storage, below are the basic points that need to remember,

• Processing or Finishing - Alkaline pH condition

• Atmospheric Pollution - The oxides of nitrogen (NOx) present in the air

• Packaging - Storage in polyethene and polypropylene bags or film containing butylated hydroxy toluene (BHT) or similar compounds, and

• Storage - Presence of moisture

How it occurs?

During the storage time, BHT (Butylated Hydroxy Toluene) released from the bag or film, especially around openings, perforations, or holes and it reacts with the atmospheric pollutants, particularly oxides of nitrogen (NOx) present in the air, and forms yellow compounds like nitrobenzenes or quinone or chinone by a chemical mechanism. This chemical substance is light yellow or lemon yellow in colour that causes yellow stains on the product.

How to reduce or stop phenolic yellowing?

• Minimize or reduce the quantity of nitrogen oxides (NOx) level in the ware-house,

• Avoid to use bags that contain the volatile antioxidant BHT in packaging that comes into contact with the textiles,

• Use phenol free carton boxes, packaging and wrapping materials.

• Keep in dry form,

• Make sure the textiles (yarn, fabric, and garment or other products) have the required pH during finishing; keep slightly acidic conditions instead of alkaline.

Furthermore, it is always better to prevent yellowing formation rather than trying to remove or fix it. Because in some cases, fabric yellowing indicates fabric degradation, in which instance the fabric may not be able to be restored to its original condition.