Modal fabric is soft, breathable, and increasingly popular in underwear, sleepwear, and activewear. But it comes with real trade-offs in cost, care, environmental impact, and durability that are worth understanding before you buy. Here’s what to watch for.
Higher Price Than Cotton or Polyester
Modal sits in the premium tier compared to regular cotton and polyester. The production process is more complex, involving the chemical conversion of wood pulp (typically beech trees) into fiber, followed by advanced finishing steps. Eco-certifications, when present, add further cost. If you’re comparing a basic cotton t-shirt to a modal one, expect the modal version to carry a noticeable markup. For everyday basics you replace frequently, that premium adds up.
Toxic Chemicals in Production
Modal is made through essentially the same process as viscose rayon, with additional chemical steps to improve the fiber’s strength. The process relies heavily on carbon disulfide, sulfuric acid, and zinc compounds. These chemicals don’t just stay inside the factory. They escape into surrounding air, water, and food sources, putting workers and nearby communities at risk.
Carbon disulfide exposure has been linked to coronary heart disease, birth defects, skin conditions, and cancer. Repeated zinc exposure can contribute to skin cancer. The severity of these impacts depends on how responsibly individual manufacturers manage their chemical waste, but the baseline process is inherently hazardous. Unlike something like linen, which requires minimal chemical processing, modal can’t be made without this industrial chemistry.
Deforestation Concerns
Modal is marketed as a plant-based, renewable fiber, and that’s technically true. But the wood pulp has to come from somewhere. According to the Forest Stewardship Council, less than 60% of forest-based textile fibers are sourced from certified forests. That means a significant portion of modal on the market may come from uncertified sources vulnerable to deforestation and illegal logging.
Uncertified harvesting threatens ancient forests, biodiversity, and communities that depend on those ecosystems. If you’re choosing modal specifically for environmental reasons, look for certifications like FSC or brands that use Lenzing’s TENCEL Modal, which tracks its wood sourcing. Without those labels, the “eco-friendly” claim is essentially unverified.
Heat Sensitivity During Care
Modal fibers don’t tolerate high heat well. Excessive temperature during ironing can scorch the fabric, and machine drying on high heat causes fiber fatigue and surface wear that shortens the garment’s lifespan. You’ll need to use low heat or steam with a pressing cloth for ironing, and tumble dry on a low setting or air dry. This isn’t a fabric you can toss in a hot dryer and forget about.
For people used to the simplicity of caring for cotton or polyester, modal’s heat limitations can feel like a hassle. It wrinkles less than cotton, which is a genuine advantage, but the trade-off is that fixing those wrinkles requires more caution.
Shrinkage Is Low but Still Present
Pure modal fabric shrinks roughly 1.4% to 1.8% after a standard wash-and-dry cycle, which is significantly less than wool (around 5% to 6%) and comparable to or better than most cotton. That said, shrinkage increases when modal is blended with other fibers. A 50/50 wool-modal blend, for example, can shrink around 3.5% to 4%. If your modal garment is a blend, check the care label carefully, because the other fiber in the mix may drag the shrinkage rate higher than you’d expect from pure modal.
Potential for Skin Reactions
Modal itself is generally well tolerated, and many people with sensitive skin find it comfortable. The risk isn’t usually the fiber. It’s the chemical residues left behind from processing. Formaldehyde finishing resins, textile dyes, glues, and other chemical additives used to treat fabric are the most common triggers for textile contact dermatitis. People with eczema or atopic dermatitis are at higher risk.
Because modal goes through more chemical processing steps than natural fibers like cotton or linen, there are more opportunities for residual chemicals to remain in the finished fabric. Washing a new modal garment before wearing it can reduce this risk, but it won’t eliminate it entirely if you’re highly sensitive to specific finishing agents.
Weaker Wet Strength Than Synthetics
Modal is specifically engineered to have better wet strength than regular viscose rayon, which is why it’s sometimes called “high wet modulus rayon.” It holds up reasonably well in the wash and resists losing its shape when damp. But compared to synthetic fabrics like polyester or nylon, modal is still a cellulose fiber that absorbs water and becomes more vulnerable when wet. It won’t fall apart, but aggressive wringing, heavy spin cycles, or rough handling while damp can stress the fibers more than it would a synthetic.
This matters most for activewear and items that get washed frequently. Over time, the combination of moisture, agitation, and heat (even low heat) wears modal down faster than a comparable polyester garment. If longevity under heavy use is your priority, synthetics still have the edge.
Limited Structure for Tailored Clothing
Modal’s signature softness and drape are assets in casual wear but a limitation for anything structured. The fabric doesn’t hold crisp lines, sharp pleats, or tailored shapes the way cotton twill, wool suiting, or even a stiff polyester blend can. It’s inherently fluid, which makes it ideal for loungewear and jersey knits but poorly suited for blazers, trousers with a crease, or garments that need to maintain a defined silhouette throughout the day. If you’re sewing with modal, keep this in mind when choosing patterns.