Cotton care instructions:
- The normal shrinkage rate of cotton fabric is around 5%. Why is it approximate? During the dyeing process, different machine tensions can lead to varying shrinkage rates. After shrinking, the fabric becomes denser.
- Avoid washing cotton fabric at high temperatures, as it can increase shrinkage.
- During the washing process, do not pour strong acid or alkali detergents directly onto the fabric; pour them into the water instead. Otherwise, it may corrode the fabric.
- Try to avoid washing cotton bedding with other materials, such as towels, as it may cause pilling.
- Differentiate between soft and hard water when washing. Hard water can form calcium and magnesium oxalate precipitates, which adsorb onto the fabric, causing it to turn grey, harden, and become brittle. Follow the washing sequence strictly and ensure thorough rinsing. Insufficient rinsing can cause the fabric to turn yellow, grey, harden, and stick to the skin.
Common Problems in Washing: Bed linen washing is the largest category of laundry volume in laundry factories, and due to the similarity of bedding stains, under certain conditions of detergents, water quality, and washing processes, their problems are universal.
- Decrease in strength of bedding fibres or some bedding fibres: After multiple washes, the fabric fibres will lose some of their cohesion and strength to varying degrees. However, if the strength decrease is too significant, it indicates problems with the washing process.
- Excessive concentration of bleaching agents. Excessive addition of bleaching agents, especially chlorine, will significantly affect the cohesion of fabric fibres.
- Low pH of chlorine bleach. During chlorine bleaching, if the pH is too low and effective chlorine is released too quickly, fibre strength will decrease significantly.
- Excessive temperature during bleaching. Prolonged heating during bleaching leads to excessive bleaching, damaging the fibres.
- High temperature and high alkalinity in the main wash. Although cotton fibres are resistant to heat and alkali, prolonged exposure to high temperatures and high alkalinity in the main wash will also cause a decrease in fibre strength.
- Low water level during washing. A low water level during washing will result in excessive detergent concentration and excessive mechanical force, damaging the fabric.
- Drum not moving during bleaching program, bleach added while stationary. Static bleaching results in locally high bleach concentrations, damaging the fabric.
- Excessive use of acid agents. Cotton fabrics are sensitive to acids, which significantly reduce the strength of cotton fibres.
- Needle hole damage on bedding: After washing, sheets and tablecloths sometimes develop holes, while towels may show lint loss or needle hole damage, mostly due to bleaching, but can also be caused by alkalis:
- Excessive local bleaching by bleaching agents leads to severe damage to bedding, specific methods include:
- Incorrect simultaneous addition of oxygen bleach and chlorine bleach to the bleaching bath.
- Insufficient bleaching temperature.
- Drum of washing machine not rotating, uneven distribution of bleach, or accumulation of bleach on bedding at temperatures of 60-70°C, leaving needle holes.
- Bleaching agent dissolves too slowly.
- Insufficient rinsing during acid neutralization, high chlorine content causes excessive reaction with acid.
- Trace amounts of metal such as iron in the bleaching bath catalyse the decomposition of bleach.
- Improper mixing of strong laundry powder or caustic soda, directly dripping onto the bedding, causing spots to appear.
- Bedding damage: Apart from sharp objects causing punctures, scratches, and damage during transportation, washing agents also cause damage.
- Incorrect bleaching process.
- Bedding contaminated with corrosive detergents not rinsed immediately.
- Misuse of detergents.
- Catalytic decomposition of trace metals in the bleaching bath.
- Gray or yellowing of bedding: Gray and yellowing of bedding are the most common phenomena, with detergent quality, water quality, bleaching agents, and washing processes all having a significant impact. In fact, it is often difficult to completely distinguish between greyness, yellowness, and even blackness in many cases.
Greyness reasons:
- Dirt not completely removed.
- High water hardness, calcium and magnesium salt deposition.
- Calcium soap deposition.
- Dirt re-deposition.
- Deposition of detergent impurities.
- Insufficient rinsing.
Yellowing reasons:
- Residual chlorine bleach on bedding.
- High iron content in water.
- Excessive use of fabric softener, overall yellowing, or fabric softener applied directly to bedding; Causes of spotting:
- Incorrect sizing step.
- Residual alkali.
- Insufficient rinsing.
- Yellowing of fluorescent whitening agent.
- Protein stains treated with chlorine bleach not thoroughly rinsed.
- Some surfactants treated with chlorine bleach.
- Colour fading or staining of coloured bedding: Due to inadequate dye fastness and stability of dyes, colour problems often occur in coloured bedding.
- Misuse of detergents, such as using chlorine bleach.
- Excessive washing temperature.
- Artificial abrasion causing colour loss.
- Poor dye fastness.
- Excessive alkalinity in washing baths.
- Stain contamination.
- Colour bleeding.
- Yellowing of bedding after bleaching:
- Bedding cannot be bleached with chlorine (e.g., synthetic fabrics, finished cotton fabrics);
- Protein stains treated with chlorine bleach.
- Excessive bleach concentration.
- Insufficient rinsing, residual chlorine bleach.
- Some surfactants treated with chlorine bleach.
- Poor whiteness of bedding after bleaching:
- Low bleach concentration.
- Short bleach time.
- Insufficient rinsing.
- Bedding turns pink:
- Rust occurs and is bleached.
- Stains are not completely cleaned, such as chili oil.
- Incomplete removal of stains: This problem is quite complex, with possible reasons including:
- Insufficient bleach concentration.
- Inappropriate bleaching temperature.
- Water level too high during bleaching.
- Too much free dirt during bleaching.
- Short bleaching process.
- Incorrect use of bleaching agents.
- Abnormal towel damage:
- Washing time too long.
- Too little laundry load.
- Water level too low.
- Multiple high-speed or high-speed dehydration during dehydration.
- High alkaline washing.
- Alkali residue on fabric.
- Incorrect use of chlorine bleach.
- Residual chlorine bleach on fabric.
- Excessive use of acid agents.