Aeptom Home - May 12 2021

Are bamboo sheets sustainable?

Bamboo bedding has gained popularity in recent years owing to its luxuriously soft and smooth texture and temperature-regulating feature. Softer than the finest cotton sheets, the texture is only comparable to silk, while at a fraction of silk's price and requires far less maintenance. 

Properties of bamboo fabric

The fabric is known for being cooling, breathable, and moisture-wicking, making it an ideal option for hot sleepers and for warm weathers. A research paper that compares the performance of cotton and bamboo in warm environment shows that "100% regenerated bamboo has a better isolation performance in hot environment. The heat storage rate in the human body can significantly be reduced by using 100% regenerated bamboo." (Solorio-Ferrales et al, 2017)

The cooling feature of bamboo fabric was due largely to its hollow morphological structure, which helps the fabric absorb excessive moisture. Bamboo fabric's moisture regain, a metric that measures the degree of moisture absorbance—the amount of moisture that a material is able to reabsorb after it has been dried—is around 11%, compared to 7% of cotton and 0.4% of polyester.

Variations of bamboo fabrics

It remains debatable as to how “green” bamboo fabric really is. While bamboo itself is an eco-friendly plant that consumes little water to grow and does not require the use of pesticide, the process of generating bamboo yarns from bamboo is more nuanced. There are mainly four types of bamboo fabrics, bamboo linen fiber, bamboo viscose, bamboo modal and bamboo lyocell, which differ in the way they are being produced.

Bamboo viscose and modal are generally deemed not as sustainable given the use of toxic chemicals in the production process. Bamboo linen fiber and bamboo lyocell, on the other hand, do not cause harm to the environment during the production process. Below is an overview of how each type of bamboo fabric is manufactured and why certain variations are not sustainable while others are.

Bamboo linen fiber: Bamboo linen fiber is not a regenerated fiber like all other types of bamboo. It was achieved through mechanically crushing the woody part of the bamboo, followed by the use of natural enzymes to break the bamboo walls to extract the fiber. This process is analogous to retting linen into flax, a practice that is harmless to the environment. Unfortunately, bamboo linen fiber obtained through this approach tends to be coarse and not suitable for bedding.

Bamboo viscose: the most commonly used variation for bamboo bedding, this is a regenerated cellulose fiber. To produce bamboo viscose, toxic chemicals such as sodium hydroxide (ie. caustic soda) and carbon disulfide are used to extract alkali cellulose, form xanthate and obtain viscose. As the process does not take place in a closed-loop, the waste can result in environmental pollution. The involvement of toxic chemicals in the manufacturing process also exposes workers to potential health hazards. If the chemicals are accidentally inhaled, workers could experience symptoms such as psychosis, heart attacks, liver damage, and blindness. Given those adverse impacts, the claim of bamboo viscose being green has now been widely challenged.  

Bamboo modal: The production process for bamboo modal is similar as the one for bamboo viscose, with toxic chemicals carbon disulfide used to derive the regenerated bamboo fibers. The small difference comes from an extra step that modal fibers need to go through after spinning, which is to stretch the fibers to increase the molecular alignment. This is to make modal fibers lighter and finer than bamboo viscose. 

Bamboo lyocell: Bamboo lyocell is also a regenerated bamboo fiber, but unlike bamboo viscose and modal, it is manufactured in a closed-loop process. It also replaces the use of toxic chemicals with an organic and harmless compound N-Methylmorpholine N-oxide (ie. NMMO) to dissolve pulp and obtain bamboo lyocell fibers. The solvent is recycled up to 99% in the closed-loop, and the minimal waste released is biodegradable and harmless to the environment. The cost of producing bamboo lyocell is higher than bamboo modal and bamboo viscose, but it is the most sustainable option for bamboo bedding.

How to choose bamboo bedding?

Like cotton, even fabrics made of the same material can differ in texture, depending on factors such as the length of the fiber and the type of weave. Fabric made with thinner bamboo yarn has softer texture and smoother surface. Weaving pattern is another key parameter that leads to distinct properties. The section below introduces three most common weaves in bamboo bedding: 

Plain: also known as percale, this is a simple criss-cross weave where the horizontal (weft) yarn goes over and then under the vertical (warp) yarn. Using a plain weave helps boost fabric's breathability, but at a cost of making the fabric less absorbent and more wrinkle-prone compared to other weaves. Texture wise, fabric with plain weave is on the stiffer end.

Twill: in a twill weave, the horizontal and vertical threads go diagonally. It is weaved in the manner that one weft thread (horizontal thread) goes over two warp threads (vertical threads) and then under one warp (diagonal lines are formed by floating every single warp and weft yarn across two or more weft or warp yarns). Twill weave is appreciated for its durability, softer texture and less wrinkle-prone relative to the plain weave. 

Sateen: this is weaved with three or more wefts over one warp or the other way around (one weft over three or more warp threads). This weaving method results in a smoother and more exquisite surface with lustrous sheen. It improves the overall texture of the fabric by making a more luxurious feel.

Lastly, caring for bamboo sheets is not a heavy-lifting task. The sheets can be machine washed in cold water, and tumble dry on a low heat setting is recommended. Bleach should be avoided when clean bamboo fabrics, as harsh chemicals can damage the fiber and result in pilling issues. Bamboo fabric has a considerable lifespan if being carefully taken care of. According to fabric suppliers, it can last for 140-150 washes. Like other fabrics, bamboo bedding gets softer with each wash. 

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