Settling the Merino wool versus Bamboo clothing debate

We often get asked about bamboo and to compare it to merino wool especially for base layer garments. In this post we review bamboo vs. merino wool from manufacturing perspective and then compare the key properties.

Manufacturing processes

How is bamboo turned into a yarn?

Bamboo clothing is made from bamboo using the bamboo leaves and the inner pith from the hard bamboo trunk, which are extracted using a steaming process and then mechanically crushed.

The pulp is then cooked in a cocktail of chemical solvents - primarily sodium hydroxide (lye, or caustic soda, as it's more commonly known) and carbon disulfide. Both are known to be harmful to humans. This solution is pushed into threads through a device like a showerhead.

The fibres are drawn out through an acid bath that makes them go hard, producing a viscose fibre ready for spinning. To get it into a usable fabric, the yarn is then often blended with other rayon fibres, spandex, and cotton.

Bamboo in it's natural state.

According to the Federal Trade Commission (FTC),

“products were made of bamboo when they were really made of rayon (viscose in the UK). In addition, some bamboo wannabes were promoted as environmentally friendly. But manufacturing rayon — even when it’s made from bamboo — is far from a “green” process.

A little Fabric 411: Rayon is a man-made fiber created from cellulose found in plants and trees and processed with chemicals that give off hazardous air pollution. Any plant or tree can be used as the source of the cellulose, including bamboo, but the fiber that’s created is rayon.”

The FTC further adds:

“[U]nless a product is made directly with bamboo fiber — often called ““mechanically processed bamboo”” — it can’t be called bamboo.”

It is not often that a government agency has such strong words, and these are tough words. The FTC has fined several large US companies for falsely claiming their products were made of bamboo, when they were not.

One cannot deny that bamboo grows quickly, and is plentiful, but the process to turn the bamboo leaf into a yarn is conveniently ignored by companies that claim to make bamboo products.

Merino Wool

Merino wool has its’ own manufacturing process. Once the Merino fleece leaves the farm it is scoured to remove any dirt and debris. It is then washed a second time to scrub down and smooth the microscopic scales on each fibre. This step is essential to stop the wool fabric shrinking when it is washed, as if left on, the scales grab each other and shrink the garment. The fibres are then lightly coated with a soft resin that further prevents them from interlocking, and the wool is dried. The tangled fibres are then opened up into a continuous length, through a “carding” process, and then further aligned and combed into “wool top” – a continuous grouping of twistless fibres. The top is spun by drawing it down into a fine roving to which twist is applied, binding the fibres together to form a continuous and strong yarn.

In summary, unlike wool, where the textile yarn is spun from the raw fibres, bamboo textile manufacture is a chemical process with some pretty toxic by products, and the end product isn’t really bamboo at all. (This sounds a lot like green washing by the bamboo industry).

Now that we have considered the manufacturing processes, one needs to consider the key attributes and properties.

Merino wool fleece. Soft and natural.

Key properties

There is lot of discussion about the key properties or benefits of different fabrics, and bamboo vs. merino wool is no different.

Odour management

Again from the FTC:

“When bamboo is processed into rayon, no trace of the original plant is left. Although a bamboo plant can resist the growth of bacteria, there is no evidence that rayon made from processed bamboo is also antibacterial.”

There are various studies available, and from the research we have seen, the most anyone seems willing to wear a viscose/rayon t-shirt for is 3 days. This is better than cotton, but far short of merino wool, where we know people have worn a t-short for weeks on end.

Merino wool is naturally anti-bacterial. Bacteria does not grow on the merino wool fabric, so it will not smell, no matter how often you wear it. We offer no guarantees that you will not smell, but our garments will not. We discuss merino wool and what makes it so special in another post.

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Warm when wet

If the garment has a high percentage of rayon, then it is slow to dry and performs the same as a cotton garment. As cotton dries, it feels cold, as it is pulling heat from your body to dry. In contrast merino wool continues to insulate when it is wet.

Merino wool is well known to help to keep you warm when it wet. Learn more here.

Burn test

Bamboo clothing burns quickly, in much the same way as cotton. Merino wool clothing has natural inflammably and will not stay lit after the flame is removed. For professional operators, merino wool no melt or drip properties are critical.

Policeman wearing Armadillo Merino as baselayers under riot coveralls

Armadillo Merino® Champion, Geoff Perrin in action.

Summary

There are some benefits to rayon or viscose, but we found that there is a lot of marketing and little truth related to bamboo products.

Specially we found:

Bamboo products cannot be called bamboo but are rayon or viscose, which can be made out of any tree or leaf. Companies calling their products bamboo are miss-leading the consumer
There are benefits of rayon or viscose clothing over cotton, but merino out performs rayon or viscose in the no smell, burn and moisture management tests.

Ultimately, we leave the decision to the consumer, but we feel in the merino wool vs, bamboo test, merino wool out performs.

Learn more about the attributes of merino wool, visit our Discover page.

Property	Bamboo	Merino wool
Moisture Management	Very absorptive, however if high percentage of rayon then slow to dry. As it dries, it feels cold.	Very absorptive, and keeps skin dry. Faster than cotton or rayon to dry, and does not give you the chills as it is drying.
Warm when wet	No	Yes
Odour management (no smell)	Up to 3 days, which is better than cotton	For as long as you like, or until you get bored of wearing the same shirt. It will not smell.
Burn test	Burns quickly, in the same way as cotton.	Will not stay lit after flame is removed.