This discoloration, often appearing as brown or yellow stains, can frustrate cleaners as it may surface hours later, leading to callbacks and dissatisfaction... 
Cellulosic browning is a common challenge faced by professional cleaners, particularly when working with natural fibres like cotton, jute, or blends found in carpets and upholstery. It often is a result of overwetting, slow drying, or the use of high pH solutions.
What is cellulosic browning?
Cellulosic browning is caused by the wicking of lignin.
Lignin: A naturally occurring gum present in cellulosic fibres such as cotton, jute and linen. When dissolved, it can wick up to the face of the fibre by capillary action and present as a brown discolouration.
What fibres & fabrics are affected by cellulosic browning?
Cellulosic fibres are affected by cellulosic browning. These are fibres derived from plants such as cotton, linen, jute, viscose and rayon. It should be noted that the backing material on some wool and synthetic fibre carpets and rugs are made from cellulosic fibres such as jute, which can lead to cellulosic browning.
What causes cellulosic browning?
- Strongly alkaline chemicals: Cleaning solutions with a high and/or buffered alkaline pH can cause the lignin in cellulosic fibres to dissolve and wick up to the face of the fibre.
- Slow Drying: Overwetting and slow drying also facilitates the wicking of dissolved lignin to the fibre surface.
What are the key prevention measures?
- Strongly alkaline chemicals: Cleaning solutions with a high and/or buffered alkaline pH can cause the lignin in cellulosic fibres to dissolve and wick up to the face of the prespray: Use a neutral or acidic prespray solution.
- Rinse: Rinse/extract using an acid rinse.
- Dry: Leave fibres and fabrics as dry as possible.
- Do not over-wet.
- Apply additional vacuum strokes to remove any excess moisture.
- Use ultra-low moisture cleaning methods for sensitive fibres
- Assist drying: Use fans and air movers to assist drying.
Encap Fine Fabric by Actichem is an ideal cleaning solution for sensitive cellulosic fibres.
It has a mildly acidic pH and can be used with low moisture cleaning methods.
How do I correct cellulosic browning?
Cellulosic browning is corrected using an acidic solution, a bleaching oxidiser or reducer. When treating cellulosic browning, remember to minimise moisture in this process.
- Acid: A quality blend of organic acids such as FibreTech Yellow Tx, Kemspec Browning Tx, or Actichem Brownaway will correct most browning.
- Reducing Agents: Reducing agents such as Actichem CTR act as an effective and safe bleaching agent to correct most stubborn browning occurrences.
- Oxidising Agents: Oxidising agents such as Spotaway Uor Conquer O2 act as an effective and safe bleaching agent to correct many stubborn browning occurrences.
METHOD 1.
- Spray/apply Actichem Brownaway or Actichem CTR undiluted or diluted 1:1 for lesser affected areas and upholstery. Avoid overwetting.
- Agitate solution using a Grandi Groomer carpet rake or upholstery brush.
- Allow 10-20 minutes reaction time.
- Rinse/extract using Actichem Rinse Pro.
- Assist drying
METHOD 2.
- Spray/apply Actichem Spotaway U diluted 1:1 or Conquer O2 diluted 1:1. Avoid overwetting.
- Agitate using a Grandi Groomer carpet rake or upholstery brush.
- Do not rinse – dry vacuum thoroughly. Assist drying.
Ultra-sensitive Fabrics & Fibres:
- Apply browning treatment to a rag and blot the affected area.
- Do not rinse, simply dry vacuum as much product away as possible to avoid adding extra moisture.
Rug Fringes:
- Rug fringes can be especially sensitive to cellulosic browning. Using a no-rinse, dry vacuum method such as Spotaway U can be the most effective treatment.
When is “browning” NOT cellulosic browning?
When there is no cellulose present.
Some natural fibres such as wool and silk are derived from animals and do not contain cellulose. It should be noted that cellulosic fibres are sometimes blended in or may be present in the backing.
- Soil Wick-Back: During the drying process of a carpet, moisture migrates up to the face of the yarn and may bring with it unrinsed soil and staining materials from the base of the fibre. This can create patches of brownish discolouration.
- Yellowing Of Wool: Wool is not naturally white due to the sulphur present in the protein molecule. Sulphur can be released by exposure to heat and alkali, causing the wool carpet to present with yellow blotches.
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