We used to think that clothes need 40°C to get properly clean. Scientific testing has proven this to be wrong: Laundry at 30°C is just as good. By lowering the temperature you can preserve your garments and save a bit of electricity!
What The Label Means
Care labels don’t say how the item should be cared for, but the maximum of what it can endure. The upper limit is set by the fabric used and the method of construction. To avoid shrinking, discoloring and rupturing the fabric prematurely, the limits are often set as follows:
- Wool: 30°C
- Cotton: 40°C
- Linen: 60°C
- Colourless cotton: 90°C
- Synthetics: Depending on type
In addition to temperature there might be added stipulations of «easy care» (marked with lines underneath the temperature symbol), meaning slower rotation and shorter duration.
Heat Accelerates Wear
There is an important caveat here. Even if an engine can handle 12.000 rpms, it will last a lot longer if you avoid habitually pushing it to screaming revs.
Subjecting a sweater to it’s thermodynamic pain threshold once or twice a week works the same way: The colour will fade, the weave will become misshapen and the texture will be ruined much faster than if the washing program was set safely within its comfort zone.
Prints such as this one from Soulland fade quickly from heat.
This is true no matter the intrinsic quality of the clothing. A case in point is our popular Libertine-Libertine Hunter shirts: This line is made with premium cotton twill, brushed to a flanell softness on most models and constructed with even, solid stitching. Our personal Hunter shirts (we have a lot, love’em) that we have washed on 30°C easy care are just as velvety soft and drapes as well today as when we bought them five years ago. On the other hand, one Hunter which was washed at 40°C regular program has gradually stiffened up and developed napping.
How Clean is 30°C?
Consumption Research Norway (SiFO), the premier independent institute for textile research in Norway, conducted several laboratory tests measuring the cleaning effect of laundry at different temperatures. The take-away is clear:
The cleaning effect tests showed that today's detergents are suitable for low temperature washing, and by selecting an efficient detergent, the cleaning result can be better at 30°C than with a less efficient detergent at 40°C.
Laitala, Boks, Klepp. 2011. "Potential for environmental improvements in laundering" International Journal of Consumption Research 35 (2): 254-264.
It appears that at temperatures as low as 40°C, removing smell, dirt and bacteria is primarily done through the detergent and not heat. Consequently there is little difference whether you set your machine at 30°C or 40°C - researchers were only able to measure an average difference of 1.9% across all detergents. Powder detergents clean more efficiently than liquid variants at low temperatures, bringing the difference even lower (our own Tangent Delicate Detergent is a bit different than the ones tested, and more closely resembles liquid wool detergent).
At 60°C the heat itself starts to kill germs, which is why the health authorities in most countries recommend washing underwear at this temperature. For regular wash for regular clothing, however, there is normally no need to go above 30°C.
Stains are the tricky part almost at any setting. Temperatures below 60°C especially struggle to dissolve fatty acids from food. We recommend pre-washing the item with a dedicated agent like Tangent GC Stain Remover which uses natural ingredients to avoid harming delicate textiles such as silk or wool.
Enjoy getting many years of use out of quality clothing!