Written by Foam Laundry | Salt Lake City's laundry pickup and delivery service.
The single most effective thing you can do to prevent shrinking is wash in cold water and dry on low heat or air dry. Most shrinkage does not happen in the wash cycle. It happens in the dryer.
That covers the basics, but different fabrics shrink for different reasons, and if you own merino wool, cashmere, or any technical outdoor gear, there is more you need to know. This guide breaks down what causes shrinkage, which fabrics are most at risk, and how to unshrink a garment that has already been damaged.
Why Clothes Shrink: The Three Causes
Shrinkage comes from three things working together: heat, agitation, and moisture. Understanding which one is driving the problem changes how you fix it.
Heat is the biggest factor. Natural fibers like wool, cotton, and linen are made of coiled protein or cellulose chains. Heat causes those chains to tighten and contract. A cotton t-shirt that fits perfectly can lose 5 to 10 percent of its length in a single hot dryer cycle.
Agitation matters for wool and other animal fibers. Wool fibers have tiny scales along their surface. When those fibers get wet and then tumble against each other aggressively, the scales interlock and the fabric tightens. This is called felting, and it is mostly irreversible.
Moisture alone can cause some relaxation shrinkage in fabrics that were stretched during manufacturing. This type usually washes out over time and is less of a concern than heat or felting.
The dryer combines all three: high heat, aggressive tumbling, and moisture from the clothes. That is why a garment can survive dozens of hand washes but shrink badly on its first trip through the dryer.
Shrink Risk by Fabric: Quick-Reference Table
| Material | Shrink Risk | Best Wash Temp | Best Dry Method | Notes |
|---|---|---|---|---|
| Cotton | High | Cold (60-80°F) | Air dry or low heat | Pre-washed cotton shrinks less; natural cotton shrinks most |
| Linen | Medium-High | Cold or lukewarm | Air dry flat | Gets stiffer with hot drying; prone to shrinkage |
| Merino wool | Very High | Cold, hand wash or delicate | Flat air dry only | Never tumble dry; felting is permanent |
| Cashmere | Very High | Cold, hand wash only | Flat air dry only | Even delicate cycles can cause felting |
| Fleece (Polartec, etc.) | Low-Medium | Cold or warm | Low heat or air dry | Synthetic fleece is more stable; avoid hot cycles |
| Nylon | Very Low | Cold or warm | Low heat or air dry | Synthetic; resists shrinkage but melts at high heat |
| Polyester | Very Low | Cold or warm | Low heat or air dry | Holds shape well; still avoid high heat |
| Spandex/Lycra | Low | Cold, delicate | Air dry only | High heat breaks down elastic fibers permanently |
| Down-blend (jackets, bedding) | Medium | Cold, delicate | Low heat with tennis balls | Needs thorough drying to prevent mold |
| Bamboo | Medium-High | Cold | Air dry or low heat | Behaves like cotton; shrinks more than synthetic |
The Fabrics SLC Residents Lose Most Often
If you live in Salt Lake City and spend time in the Wasatch, you probably own more high-shrink gear than the average person.
Merino wool is everywhere in Utah. It is the base layer of choice for skiing, hiking, and trail running because it regulates temperature and resists odor. It is also one of the easiest garments to destroy in the laundry. A merino base layer that costs $80 to $150 can felt permanently in a single normal dryer cycle. Always lay merino flat to dry. Never tumble dry it, even on low.
Fleece mid-layers are more forgiving than merino, but repeated high-heat drying degrades the fibers and causes pilling. Dry on low heat or hang dry.
Technical shells and softshells are usually nylon or polyester with a DWR (durable water repellent) coating. They do not shrink easily, but high heat degrades the DWR coating. Dry on low or air dry, then reactivate the coating with a brief tumble on low once the shell is fully dry.
Salt Lake's dry climate means outdoor gear dries fast when hung. Air drying merino or fleece indoors in Utah winter takes 4 to 6 hours. You do not need the dryer.
How to Prevent Shrinking: The Full List
Use cold water. Cold water does not trigger fiber contraction the way hot water does. It cleans clothes effectively for everything except heavily soiled items. At Foam, we wash all garments in cold water by default.
Turn clothes inside out. This reduces friction on the outer surface and helps garments hold their shape during agitation.
Use a gentle or delicate cycle. Less agitation means less risk of felting in wool and less mechanical stress on other fibers. Reserve normal and heavy-duty cycles for durable items like jeans, towels, and cotton sheets.
Dry on low heat or air dry. Low heat is not just better for shrinkage prevention. It extends the life of almost every garment. High heat wears out elastic, degrades synthetic coatings, and causes cotton to pill.
Remove clothes promptly from the dryer. Leaving hot clothes in a stopped dryer lets residual heat continue working on the fibers. Pull them out while they are slightly damp and finish drying on a rack or flat surface.
Read the care label. The label is the manufacturer telling you exactly how the fabric was tested. If it says "lay flat to dry," they mean it.
The Unshrinking Trick (It Actually Works for Some Fabrics)
If a garment has already shrunk, you may be able to recover it, depending on the fabric and how badly it shrank.
This works best on wool, cotton, and linen. It does not work on felted wool (the scales have locked together permanently) or fully set synthetic shrinkage.
What you need: Hair conditioner or baby shampoo, a clean basin or sink, and cold water.
Step 1. Fill the basin with cold water and add about one tablespoon of hair conditioner or baby shampoo. Stir to mix.
Step 2. Submerge the garment fully and let it soak for 20 to 30 minutes. Do not agitate or wring.
Step 3. Remove the garment and gently squeeze (do not wring) to remove water. Do not rinse.
Step 4. Lay the garment flat on a clean towel. Roll the towel and garment together and press gently to absorb more water.
Step 5. Unroll, then lay the garment flat on a dry surface. While it is still damp, gently stretch it back toward its original shape by hand. Use a tape measure against the original size if you have one.
Step 6. Let it air dry completely while stretched. Pin the edges to a blocking mat if you want precision.
The conditioner relaxes the fibers by acting as a lubricant, which allows them to be manually stretched before they set in their shrunken position. This works on cotton and wool that shrank from heat but has not felted. It will not undo mechanical felting.
Why Professional Laundry Services Help
At Foam, we see garment damage from laundry mistakes every week. The most common: a merino base layer washed hot or put in the dryer, a cotton button-down that shrank two sizes, a Patagonia fleece with permanent heat pilling.
We wash everything in cold water. We use low heat or air dry for any item with a delicate, hand wash, or lay flat label. Customers who hand over gear they care about get it back in the same condition it left.
For Salt Lake City residents with expensive outdoor gear, a professional laundry service that reads care labels is not a luxury. It is the difference between a base layer that lasts four ski seasons and one that lasts one.
Frequently Asked Questions
Does cold water actually prevent shrinking?
Yes. Cold water reduces heat exposure, which is the main cause of fiber contraction in natural fabrics like cotton, wool, and linen. It also reduces the energy cost of washing. Cold water cleans clothes effectively for everyday loads. Reserve warm or hot water for heavily soiled items or bedding that needs sanitizing.
Can you unshrink clothes after they have already shrunken?
Sometimes, yes. For cotton, wool, and linen that shrank from heat, soaking in cold water with hair conditioner and then manually stretching the garment while damp can recover much of the lost size. Felted wool cannot be unfelted. Garments that went through multiple hot cycles have less chance of full recovery.
Which fabrics shrink the most?
Merino wool and cashmere shrink the most, and the damage is often irreversible because they can felt. Natural cotton and linen also shrink significantly. Bamboo fabric behaves similarly to cotton. Synthetic fabrics like polyester, nylon, and most fleece are more stable, but they still degrade at high heat even if they do not shrink.
Does air drying prevent shrinking?
Air drying is the safest drying method for almost every fabric. Without heat, fabrics cannot thermally contract. Laying items flat is best for wool, cashmere, and anything that might stretch on a hanger. Hanging works fine for cotton, linen, and synthetics. In Salt Lake City, the dry air means most garments air dry significantly faster than in humid climates.
Foam Laundry provides laundry pickup and delivery in Salt Lake City, Utah. Plans start at $24.99 per week with same-day turnaround and free pickup and delivery.