Does Acrylic Shrink? How to Safely Wash Acrylic Fabric

Acrylic does not shrink significantly in cold or warm water under normal washing conditions, but high dryer heat above 60°C (140°F) can cause permanent deformation — similar to polyester. The bigger care risk with acrylic is pilling from mechanical agitation, not shrinkage. Unlike wool, which shrinks through felting triggered by agitation and moisture, acrylic is agitation-resistant but heat-sensitive.

Acrylic: A Synthetic Wool Substitute

Acrylic is a synthetic fiber made from polyacrylonitrile (PAN) — a thermoplastic polymer with an average molecular weight of approximately 100,000, comprising roughly 1,900 monomer units. To carry the “acrylic” label in the United States, the fiber must contain at least 85% acrylonitrile monomer by weight, with typical commercial variants using vinyl acetate or methyl acrylate as comonomers to improve processing and dyeability.

Developed as a lower-cost alternative to wool, acrylic mimics wool’s warmth and soft texture while offering better machine-washability and color fastness. The fiber is lightweight, hypoallergenic, and takes dye readily, making it popular for knitwear, blankets, and outdoor apparel. However, acrylic is not heat-set in the same manner as polyester — it requires a heat-relaxation step during finishing to set the garment’s shape, which makes it slightly more sensitive to high temperatures during home care.

Unlike wool, which is digested by clothes moth larvae, acrylic is moth-resistant. When burned, acrylic fiber melts and emits acrid smoke with a distinctive sour smell, classifying it as significantly more flammable than natural protein fibers like wool or silk.

How Much Does Acrylic Shrink?

Acrylic’s dimensional stability depends heavily on water temperature and construction. Industry textile testing and care label standards (following ISO 3759 and AATCC test methods) document the following shrinkage behavior:

The primary shrinkage mechanism in acrylic is not traditional relaxation shrinkage but rather heat distortion — an irreversible shape change caused by thermal softening of the PAN polymer. When acrylic is exposed to temperatures above its glass transition point (approximately 60–65°C for standard acrylic), the fiber softens and can warp, resulting in a hardened, misshapen garment that cannot be restored by re-washing.

Knit constructions are particularly susceptible to shrinkage and distortion because their loop structure allows more dimensional reorganization under heat and moisture than woven fabrics. Acrylic jersey and sweater knits routinely show 2–4% relaxation shrinkage on first hot-water washes, even when the care label recommends a gentler cycle.

Compared to polyester, acrylic behaves similarly in terms of heat sensitivity — both are thermoplastics that can distort under high dryer heat. However, acrylic has a slightly lower heat tolerance than PET polyester, requiring more conservative dryer settings.

Pilling: The Real Acrylic Problem

While shrinkage is a manageable risk, pilling is acrylic’s most persistent and unavoidable durability challenge. Acrylic pills more readily than almost any other apparel fiber, largely due to the combination of its fiber strength and surface texture.

Pilling occurs when short surface fibers — which are inherent to the spinning process in acrylic yarns — break free from the yarn structure under friction and roll into small, visible balls (pills) that cling to the fabric surface. Acrylic fibers have high tensile strength relative to their diameter, meaning the pills do not shed easily and accumulate over wash cycles. In standard Martindale abrasion testing, acrylic fabrics typically reach unacceptable pilling ratings (Grade 3 or below on a 5-point scale) faster than cotton, linen, or silk equivalents.

Low-pilling acrylic variants exist, achieved through modifications to yarn spinning (modified spinnerets, improved fiber cutting consistency, or blend with anti-pilling staple fibers), but standard economy-grade acrylic knitwear remains highly prone to pilling with regular wear.

Pilling prevention strategies:

• Wash on a gentle or delicate cycle with cold to warm water (30–40°C)
• Use a mesh laundry bag to reduce mechanical friction between garments
• Turn garments inside out before washing to protect the face fabric
• Avoid washing with abrasive companions (denim, towels with heavy texture)

Pilling removal: A battery-operated fabric shaver or sweater comb is the most effective tool for removing established pills. De-pilling does not damage the underlying fabric if performed carefully on a flat surface.

Acrylic Pilling vs. Shrinkage: A Visual Guide

How to Wash Acrylic Safely

Safe acrylic care centers on two principles: keeping water temperature in the cold-to-warm range and minimizing mechanical agitation. Follow these guidelines to maximize the lifespan of acrylic garments:

• Water temperature: Use cold to warm water (30–40°C / 86–104°F). This range keeps shrinkage below 3% even for knit constructions.
• Wash cycle: Select the gentle or delicate cycle. High-speed agitation accelerates pilling and provides no benefit for acrylic.
• Detergent: A standard gentle or normal laundry detergent is sufficient. Fabric softener can be used in small amounts to reduce static and improve hand feel, but overuse may coat fibers and reduce breathability over time.
• Laundry bag: Placing acrylic knitwear inside a mesh laundry bag significantly reduces surface abrasion and pilling, especially in top-loading machines.
• Drying: Tumble dry on the LOW heat setting only. Remove garments before they are fully dry to prevent over-heating in the final stages of the cycle. For best shape retention, lay acrylic knitwear flat to dry on a clean towel — acrylic knits can stretch under their own weight when hung.
• Ironing: If ironing is necessary, use the lowest iron setting (1 dot / 110°C / 230°F) with no steam. Place a pressing cloth between the iron and the acrylic fabric. Never apply direct high heat — the fiber will scorch or melt.

For items with heavy piling or surface texture (such as acrylic fleece pullover), hand washing in cold water with gentle agitation is the most protective option, though machine washing on delicate in a laundry bag produces acceptable results for regularly worn items.

Frequently Asked Questions

Q: Does acrylic shrink in the wash?
A: Acrylic has low shrinkage risk in cold to warm water (30–40°C), showing less than 1% dimensional change in cold water and 1–3% in warm water. Hot water above 60°C causes 3–6% shrinkage with real distortion risk. The main concern is heat distortion, not traditional water-based shrinkage — keeping wash temperatures below 40°C and dryer heat on low minimizes risk.

Q: Can you put acrylic in the dryer?
A: Low heat only. High dryer heat above 60°C permanently distorts acrylic fiber by thermally softening the polyacrylonitrile polymer — this distortion is irreversible and cannot be fixed by re-washing. Many acrylic knitwear items are best laid flat to dry to maintain their shape and avoid both heat damage and the stretching that occurs when wet acrylic hangs.

Q: Does acrylic shrink like wool?
A: No — acrylic does not felt like wool and cannot shrink 30% or more from agitation. Wool shrinks through felting, a process in which moisture, heat, and mechanical action cause the scales of the cuticle layer to interlock, compressing the fabric. Acrylic has no cuticle scales and is agitation-resistant. Its behavior is closer to polyester (heat-sensitive, agitation-resistant) than to wool (agitation-sensitive, felting-prone). Acrylic’s shrinkage risk comes from heat distortion, not felting.

References

• Wikipedia. (2026). Acrylic fiber. https://en.wikipedia.org/wiki/Acrylic_fiber
• ISO. (2011). ISO 3759:2011 — Textiles — Preparation, marking and measuring of fabric specimens and garments in tests for determination of dimensional change. International Organization for Standardization. https://www.iso.org/standard/65964.html
• AATCC. (2026). American Association of Textile Chemists and Colorists — Technical Manual. https://www.aatcc.org/
• Cotton Incorporated. (2026). Care Processing: Washing and Care Guidelines. https://www.cottonworks.com/
• Textile Exchange. (2026). Knowledge Base — Fiber Reference Guide. https://www.textileexchange.org/knowledge-base/