Washing Silk at 40 Degrees: A Comprehensive Guide

As a silk lover, I know how important it is to properly care for this luxurious and delicate fabric.

Silk adds beauty and elegance to any wardrobe, but it requires some special handling when it comes time for laundering.

The main question many of us have is: can silk be washed at 40 degrees Celsius?

Through my experience of caring for silk over the years, I’ve learned the ideal washing temperatures, risks of high heat, and best practices for keeping silk looking its absolute best. 

Read on for a complete guide to washing silk at 40 degrees, with plenty of tips for preserving your silk items.

Understanding Silk Fabric

Before we dive into temperatures, let’s quickly overview silk as a fabric:

• Silk is made from natural protein fibers produced by silkworms. This gives it a shimmery, luxurious look and feel.
• However, as a protein fiber, silk is very delicate and prone to damage from improper care.

Some key characteristics of silk:

• Silk has poor elasticity and resists creases. This means it is prone to tearing when stretched.
• The fibers can easily degrade when exposed to excess moisture or heat.
• Silk is known for its vivid, rich colors. But dyes can fade or bleed if washed improperly.
• Different types of silk (mulberry, tussah, etc.) have slightly different properties.

The Ideal Washing Temperature for Silk

The general guidance is to wash silk in cool, delicate cycles to avoid damage. Specific recommendations are:

• Hand wash in lukewarm water around 20-30°C. This is the most gentle method.
• Machine wash on the delicate cycle in lukewarm water. Ensure your machine has a setting of 20-30°C.
• If machine washing in warm water, the ideal temperature for silk is 30°C.
• Temperatures above 30°C risk harming silk fibers. 40°C is too hot for delicate silk clothing.

So 30°C is the recommended upper limit for silk laundry. But is 40°C ever okay? Let’s explore that next.

Risks of Washing Silk at 40 Degrees

Washing silk at 40°C is not recommended due to the high risk of damage:

• Fading – Silk dyes can bleed or fade in water that is too hot. Even colorfast dyes may fade over time with repeated 40°C washing.
• Shrinkage – The fibers may shrink at higher temperatures. One hot wash might slightly shrink your silk blouse or shirt.
• Texture damage – Excess heat damages the molecular structure of silk, causing dull, stiff fabric that loses its soft drape and sheen.
• Weakened fibers – High heat weakens the protein structure of silk, causing tears and splits. Your silk garments will not last as long.

The science: Why does heat ruin silk?

• Hot water causes silk’s crystalline structure to relax and loosen. This deforms the fibers.
• Temperatures above 35°C break down sericin protein in silk. Sericin gives silk its smooth surface.
• Heat also unravels the hydrogen bonds that give silk strength and elasticity.

So for long-lasting silk, it’s best to launder below 30°C whenever possible.

Washing Silk at Lower Temperatures

The best way to care for silk is by washing it in cold water below 30°C. Here are some benefits of lower temp silk washing:

• Preserves vibrancy – Cool water helps dyes retain their color intensity and prevents fading.
• Avoids shrinkage – Silk’s fibers stay relaxed and flexible when washed cool, preventing shrinkage.
• Maintains texture – The natural elasticity and luster of silk stay intact with gentle cold-water cleaning.
• Extends lifespan – Keeping silk out of hot water prevents damage to the delicate fibers. Your silk pieces will last for many more wears.

I highly recommend hand washing or the delicate cycle in cold tap water for silk clothing, scarves, and accessories.

It only takes a few extra minutes but pays off in the long run by allowing you to enjoy your silk for many years.

Explore the safety of lower temperatures in my guide on washing silk at 30 degrees.

Washing Silk Bedding for Hygiene

While specialty silk blends designed for bedding may be more resilient, 100% silk bed sheets, pillowcases, and blankets still require gentle care.

However, proper hygiene is also essential for bed linens. Here are some tips:

• Wash silk bedding at 30°C maximum, using a mild detergent safe for silk.
• For severe soiling, pre-treat stains then wash in cold water instead of hot.
• Use an extra-gentle cycle on the washing machine to minimize agitation. Or hand wash in the sink for utmost care.
• Rinse with cool water and avoid excessive twisting or wringing when removing excess moisture.
• Occasionally wash silk pillowcases at 40°C if concerned about bacteria, but avoid this heat with silk sheets or quilts.

The idea is to use the lowest temperature that will sufficiently clean your silk bedding and remove allergens. For regular washing, 30°C or cooler is best.

Different Silk Types and Their Care

Not all silks are equally delicate – some are more resilient by nature or have enhancers to improve washability. Here are a few common types:

• Mulberry silk – Very fine and delicate. Limit washing to 30°C max.
• Tussah silk – Coarser fibers, but still requires cool washing.
• Dupioni silk – Heavier silk textured with nubby slubs. More durable but still wash gently.
• Silk chiffon – Extremely fragile with loose weave. Dry clean only recommended.
• Silk charmeuse – Lightweight with a satiny finish. Hand or delicate machine wash.
• Silk habotai – Lightweight and quite sturdy. Can withstand 30°C machine washing.
• Silk shantung – Similar to dupioni with a nubby texture. Carefully machine wash cool.
• Washable silk – Treated for durability. Preferably wash at 30°C to maintain quality.

The takeaway is to always refer to the garment tag for specific instructions. And when in doubt, opt for cooler temperatures to prevent irreversible damage.

Here’s a table with the recommended washing temperatures for different silk fabrics:

Best Practices for Washing Silk

Follow these best practices anytime you launder silk clothing or home linens:

• Pre-treat any stains by directly dabbing the spot with a mild detergent and cool water. Avoid vigorous rubbing.
• Check the item’s tag – some silks must be dry cleaned. If machine washing, use the delicate cycle.
• Wash similar colors together to prevent dye bleed. White vinegar helps set dyes.
• Use a mild liquid detergent, no bleach. Look for “silk-safe” on the label.
• Fill the washer or sink with cool water at 29°C or below. For whites, you can go up to 30°C.
• Let items soak briefly to loosen dirt. Gentle agitation only!
• Rinse thoroughly in cool water to remove all soap residue.
• Roll silk garments in a towel to absorb moisture. Avoid twisting, wringing, or harsh handling when wet.
• Lay flat or hang to dry out of direct sunlight. Iron on low while still slightly damp if needed.

Proper silk washing is a labor of love – both for your cherished fabrics and the planet. The extra 10 minutes of care preserves the integrity of this eco-friendly natural fiber.

Can I Wash Silk in Warm Water If I Wash It Quickly?

Even a short wash cycle in warm 40°C water can damage silk.

The exposure to high heat, even for a few minutes, can cause fading, shrinking, and loss of luster. It’s best to stick to cooler water temperatures even for quick rinse cycles.

I’ve researched and shared insights on the feasibility of washing silk at 60 degrees.

Can I Put Silk in the Dryer If I Use a Low Heat Setting?

It’s best to air dry silk instead of machine drying, even on low heat. The tumbling motion and warm air of a dryer, even on delicate settings, can damage silk’s fibers.

The friction of the dryer can pull on snags or unravel delicate silk. Lay flat or hang silk pieces to air dry instead.

What Kind of Detergent Should I Avoid for Washing Silk?

Steer clear of regular laundry detergents, powder detergents, and anything with brightening agents or bleach when washing silk.

The additives and harsher chemicals in these products can fade dyes and dry out silk fibers. Opt for liquid detergents marked as “gentle”, “delicate”, or “silk-safe”.

I swear by Heritage Park Laundry Detergent (link to Amazon) for all my silk garments. It’s gentle, effective, and leaves the silk feeling wonderfully smooth and looking vibrant.

Conclusions

While it may be possible to wash silk at 40°C, this hot temperature risks shrinking, damage, and color loss.

To safely clean silk clothing, bedding, and other items, wash in cold water below 30°C whenever possible.

Take extra care by hand washing or using the delicate cycle. With proper handling, your silk can remain vibrant and beautiful for many years to come.

What matters most is using an appropriate washing method for each silk garment or piece of bedding.

Always defer to the item’s tag for instructions, and when in doubt, err on the side of lower temperatures.

With some basic silk care knowledge, you can keep your silk looking luxurious wash after wash.