Will Your Jumper Shrink in the Dryer? A Comprehensive Guide to Preventing Shrinkage

by Simon Kensington

Jumpers, made from wool, cotton, or other fabrics, are often wardrobe staples for keeping warm and stylish. However, one common concern when caring for these garments is shrinkage. Can jumpers shrink in the dryer? Unfortunately, the answer is often yes. Depending on the fabric and care process, your favourite jumper may become too small if not appropriately handled. In this guide, we'll explore why jumpers shrink, how to prevent it, and what you can do to care for your sweaters without risking damage.

Why Do Jumpers Shrink in the Dryer?

Shrinkage occurs when the fibres in your jumper contract due to heat, agitation, and water. Different fabrics respond in unique ways, but generally, high temperatures and excessive movement in the dryer cause fibres to tighten, which results in a smaller, tighter fit.

Here’s a closer look at why specific materials like cotton and wool are particularly susceptible to shrinking:

Cotton Jumpers: Cotton is a natural fibre that can shrink significantly if exposed to high heat. When washed in hot water or dried on a high setting, cotton fibres contract, causing the garment to become smaller. Many 100% cotton items are pre-shrunk during manufacturing, but even so, repeated exposure to heat can cause further shrinkage.
Wool Jumpers: Wool is especially vulnerable to shrinking because of its structure. Wool fibres have microscopic scales that lock together when exposed to heat and moisture, leading to felting. This can make wool jumpers shrink drastically if not washed or dried correctly.

Preventing Shrinkage: Best Practices for Washing and Drying Jumpers

To keep your jumpers from shrinking, proper washing and drying techniques are essential. Here are key tips for both wool and cotton jumpers:

1. Washing Your Jumper Safely

Read the Care Label: Always check the care instructions on your jumper’s label before washing. Labels provide vital information on how to clean and dry the garment properly. Some fabrics may only be suitable for handwashing, while others require specific washing machine settings.
Cold Water Wash: Cold water is your safest bet for washing cotton or wool jumpers. Hot water can cause fibres to contract, so using cold water minimises this risk. Choose the cold or delicate cycle if you're using a washing machine.
Gentle Detergents: Harsh detergents can weaken fabric fibres over time. Opt for mild, wool-safe or fabric-specific detergents that are gentle on your clothing. These detergents clean effectively without damaging the structure of the fibres.

2. Drying Your Jumper: Avoiding the Dryer Altogether

Air Drying Is Key: The best way to prevent shrinkage is to avoid the dryer altogether. Air drying your jumper on a flat surface will help maintain its shape and prevent fibres from contracting. Lay the jumper flat on a clean towel and reshape it to its original size. Wet wool or cotton jumpers can be stretched out by hanging them out due to the weight of the water.
Avoid Direct Sunlight or Heat: While air drying is recommended, it’s important not to expose your jumper to direct sunlight or heat sources like radiators. Heat can still cause fibres to shrink, even when air drying—instead, dry jumpers in a shaded, well-ventilated area.

Using the Dryer on a Low Heat Setting: If you must use the dryer, choose the lowest possible heat setting. Some dryers have a "delicates" or "air dry" mode with minimal heat. This will take longer, but it significantly reduces the risk of shrinking. However, if possible, it's best to avoid the dryer altogether for wool jumpers.

How to Unshrink a Jumper That’s Already Shrunk

If you’ve accidentally shrunk your jumper, all hope is not lost. There are ways to “unshrink” garments, although results vary depending on the fabric and the extent of the shrinkage. Here’s a step-by-step guide to help you restore a jumper’s size:

Fill a Basin with Lukewarm Water and Add Conditioner: Use lukewarm water and add a tablespoon of baby shampoo or hair conditioner. The conditioner helps soften the fibres, making them easier to stretch back into shape.
Soak the Jumper: Submerge the shrunken jumper in the solution and let it soak for 20-30 minutes. This relaxes the fibres, preparing them for reshaping.
Gently Stretch the Jumper: After soaking, remove the jumper and gently press out the excess water without wringing or twisting. Lay it flat on a towel and carefully stretch the fabric back to its original size. Don’t force the stretch—apply even, gentle pressure.

Air Dry Flat: Lay the jumper flat on a clean, dry towel and leave it to air dry. While drying, you may need to gently stretch it occasionally to maintain the shape.

Common Mistakes That Lead to Shrinking

Knowing what not to do is as important as knowing the proper care steps. Here are some common mistakes that often lead to shrinking jumpers:

Using Hot Water: Hot water is a top culprit in shrinkage. Even if you're in a hurry, avoid using the hot wash cycle for wool and cotton jumpers.
High Heat in the Dryer: The dryer’s heat is a significant factor in shrinking, especially for wool and cotton fabrics. If you must use a dryer, always use low or no-heat settings.
Overloading the Washer or Dryer: Stuffing too many clothes into the machine increases friction and agitation, which can weaken and shrink fibres. Washing your jumpers in smaller loads is better to minimise this risk.

Skipping the Gentle Cycle: Using a regular or heavy-duty cycle can be too aggressive for delicate jumpers. Always opt for the gentle or wool cycle to reduce agitation.

Why Certain Fabrics Shrink More Than Others

Different fabrics react to heat and water in varying ways. Understanding how materials behave can help you make better choices when washing and drying jumpers:

Cotton: Natural fibres like cotton tend to shrink when exposed to heat because the fibres contract and become denser. Pre-shrunk cotton jumpers are less likely to shrink, but improper washing or drying can still cause some shrinkage over time.
Wool: Wool fibres have a structure that includes tiny scales. When exposed to heat and moisture, these scales interlock, causing the wool to shrink and felt. This makes wool particularly susceptible to damage in the dryer.

Synthetic Blends: Fabrics like acrylic or polyester, often blended with wool or cotton, tend to shrink less but may still be affected by high heat. These fibres are more durable but can lose shape and quality if not cared for properly.

Final Thoughts

Jumpers can shrink in the dryer if exposed to high heat and agitation, but with the proper care, you can keep them in excellent condition. Air drying is the safest option for wool and cotton jumpers, while cold water washes and low-heat drying cycles can help prevent shrinkage. Always check the care label, use gentle detergents, and carefully handle your jumpers to ensure they remain the perfect fit for years.