These garments can be washed in a similar way to 65% polyester/35% cotton garments but there are a few things to consider.
Differences between 50-70% cotton / 30-50% polyester (cotton-rich) to 65% polyester/35% cotton garments:
Because of the increased amount of cotton in the garments, they will take longer to dry, although still quicker than 100% cotton.
Colored garments may appear to lose color more quickly as the cotton is removed, although at a significantly lower rate than 100% cotton.
Garments made from cotton-rich fabrics will not have the same appearance after tunnel finishing as polyester-rich fabrics.
White and colored garments should be separated and classified according to the level of soiling and their color.
Polyester/cotton garments must be washed separately from other fiber blends, e.g. 100% cotton or 100% polyester.
A) White garments
Consult your detergent supplier:
In consultation with your detergent supplier, a wash process should be developed to remove the soiling and staining. This should involve the use of a blend of anionic and non-ionic detergents. Soap-based products should not be used, to avoid the formation of scums which cause greying of the garments.
Brightening and stain removal:
Optical brightening agents can be used to enhance the whiteness if required. Either chlorine or oxygen-type bleaching agents can be used to remove stains; these must be completely removed from the garments (especially chlorine) before the garments are tunnel-finished, to avoid yellowing.
Rinsing:
There must be sufficient rinsing to remove all chemical residues from the fabric before tunnel finishing. The pH and alkalinity of the garments after rinsing should be checked, not only the rinse water.
Softeners:
If softeners are used, it must be remembered that excessive softener build-up can contribute to premature damage, like pilling formation or fiber hairiness on fabric surfaces, as well as in some cases causing a yellowing effect. This may affect propensity for soil catching.
B) Colored garments
Brightening agents:
When washing colored garments, the use of optical brightening agents is not necessary. If used, they can give the impression of color loss because of their masking effect.
Bleaching agents:
The use of bleaching agents should be avoided except in exceptional cases as they can affect the colour and have the potential to damage the fabric if not fully removed during rinsing.
Bordeaux (401) and dark colors:
Bordeaux and dark colors are more susceptible to color bleeding. It is important to allow enough water in pre-washing and main wash to make sure that excess dyestuffs from the dyeing process are dissolved and washed out of the garments before wearing. If excess dyestuffs are still attached to the garment after laundering, it can increase the risk of color bleeding during wear.
It is recommended to pre-wash bordeaux and dark colors 2-3 times according to specified temperature in a single washing machine where loading capacity and liquor ratio can be adjusted.
Loading capacity: maximum 50%
Liqour ratio main wash: minimum 1:5
Liqour ratio rinsing: minimum 1:6
C) General
The wash load should be roughly 2/3 of the machine loading capacity to allow sufficient mechanical action and to reduce the chance of creasing.
Washing:
The washing process can be split into the following stages, depending on the level of soiling:
- pre-treatment of the garment
- pre-wash – to remove solid matter so that detergents act on the soiling and staining effectively
- main wash – at a temperature and pH that reflects the level of soiling
- bleaching for white garments
- rinsing – which can include anti-chlorine treatments, softening or other additions.
Caution:
To avoid setting creases (thermal shock) when the wash load is being cooled down from temperatures of 50-60°C, the rate of cool-down should not exceed 3-4°C per minute.
It is recommended to have a sufficient rinsing process, when using bleaching and disinfection chemicals in the washing process, to avoid corrosion on metal trims e.g., buttons and zippers. The hydro extraction of the garments should not be excessive, otherwise creases can set in. The extraction should also be set to allow 35-45% water by weight to be left in the garments for optimum tunnel finishing.
Press-extraction is not recommended nevertheless if the garments are being press-extracted, the pressure should be kept as low as possible to avoid creasing, breaking of buttons and zippers, and imprinting onto the fabric. Any tumbling to open the press cake should be done at room temperature.
Drying:
Garments can be dried or finished by tumble drier or tunnel finisher.
If they are tumble-dried, the load should only be 50-60% cotton/40-50% polyester, otherwise there is a possibility of over-drying, which can cause damage to the garment or shrinkage problems. The tumble-drying cycle should include a cool-down period so that creasing is avoided.
If the garments are tunnel-finished, they should be fed into the tunnel finisher separately from other blends and finishes so that efficient drying and finishing takes place. A fabric surface temperature of 130-140°C is adequate for good appearance. Bone-dry garments (garments where no water is left after washing) must not be tunnel finished as this can cause problems such as shrinkage and scorching (change of surface color and texture due to heat).