Key Points
- Polyester is a man made fiber derived from from plastic (Polyethylene Naphthalate)
- Polyester can be prone to shrinkage at high temperatures but the extent is driven by the manufacturing process.
- Heat setting and drying temperatures during manufacture affect the ease and amount of shrinkage.
- Read the care label, or use lower temperatures when washing to be safe.
Polyester is a very common fabric and has grown popularity in popularity due to some of its superior qualities over cotton such as wrinkle resistance, ability to fade less and durability.
Cotton is a natural fiber affording it better breathability and other interesting properties which is sometimes why polyester and cotton are blended together to compliment eachother.
With all of polyesters remarkable properties, the question arises, is polyester prone to shrinkage like other fabrics are for example cotton ?
Does polyester shrink? Polyester is quite durable and typically resists shrinkage unless exposed to high temperature for long enough. In home laundries, this could happen when temperatures are greater than 70°C (158°F) in the dryer or washing machine. The extent and precise temperature depends largely on how the garment was made.
What is Heat Setting?
Heat setting is a temperature based treatment used in textile manufacturing processes that improve the overall ability of a fabric to maintain shape, improve crease resistance, strengthen, color and softness.
It is quite common practice to apply heat setting to fabrics, others include nylon , woven and knitted fabrics.
Heat setting polyester involves applying a temperature of between 170°C - 210°C (338°F - 410°F) for approximately 15-40 seconds.
The temperature is far higher than achievable in the home laundry, but less adequate manufacturing processes could affect the quality and make items more prone to shrinkage in domestic washers and dryers.
Polyester is stretched when dyed
To add more colour to polyester fabric, dyes are used to give more vibrancy.
When dyes applied, it can cause an undesirable amount of wrinkling in the fabric and the manufacturer will stretch the polyester fabric in high heat while the dye is drying.
The pre-stretching of the fabric causes the fiber to take a shape larger than it would be naturally, this also means that the fiber can shrink back to its natural shape and size once temperatures are close to the drying temperature.
What temperature will polyester shrink
The temperature at which polyester shrinks is linked to the temperature at which it was heat set and the extent it was stretched when manufactured, but conservatively, polyester shouldn't shrink at temperatures below 70°C (158°F) .
Its advisable to follow the care label instructions of your garment as it will indicate what is safe to do.
In practical terms it will be fine under normal washing conditions, but if you have a blended garment, or one that is quite precious then be cuation and set tumble dryer to a low setting.
No 2 manufacturing processes are likely to be the same which means quality can vary so exercise caution on the first wash.
