DU 302: How to Wash Raw Denim
Summary
Everything you need to know about washing raw denim comes down to one equation: Water + Heat + Agitation = Shrinkage. Add more of any variable and you increase the effect on your fabric and your fades; reduce them and you stay in control. The goal is always the same — get the dirt out while keeping as much surface indigo in place as possible, so the fades you earn through wear stay sharp and personal.
Q&A
How do you wash raw denim without ruining it?
The safest method is a cold tub soak: fill a bathtub with cold water, add a small amount of gentle detergent (Woolite Dark, a dedicated denim wash, or diluted Dr. Bronner's), submerge your jeans for 20–40 minutes without agitating, rinse twice, and hang dry. Cold water, no agitation, and air drying eliminate the three main causes of shrinkage and uncontrolled fading. Never use a dryer.
Can you put raw denim in a washing machine?
Yes, with caveats. Use cold water, the gentlest cycle available, and turn your jeans inside out before loading. Use less detergent than you think you need. Never put raw denim in the dryer afterward — always hang dry. Machine washing is acceptable but gives you less control than a tub soak, particularly over agitation.
How often should you wash raw denim?
Less often than regular jeans. Every wash removes some surface indigo, which competes with the wear-pattern fading that makes raw denim special. Wash when the jeans smell, when there's visible dirt that spot cleaning can't address, or when hygiene requires it. Spot clean minor marks between washes. Trust your nose more than the calendar.
Does vinegar help preserve raw denim color?
Yes. Adding about a cup of distilled white vinegar to your wash helps neutralize the mineral compounds released by indigo and sulfur dyes, slowing color loss. It also acts as a mild fabric softener. The vinegar smell dissipates completely as the jeans dry. It's worth doing on the first wash especially — though it will slightly slow the development of sharp wear-pattern fades by fixing some dye that might otherwise wear away unevenly.
What is the one rule of raw denim care?
Never put raw denim in the dryer. The dryer combines all three damaging variables simultaneously — heat, moisture, and mechanical agitation — at their worst. It shrinks the fabric, produces flat uniform fading rather than the beautiful differential fading of wear patterns, and causes damage that cannot be undone. Always hang dry.
Test Your Knowledge
Click each answer to reveal whether it's correct.
1. What are the three variables that cause shrinkage in raw denim?
A. Cotton, indigo, and tension
❌ Incorrect. Cotton, indigo, and tension are properties of the fabric, not variables you control in the wash. The three variables that cause shrinkage are water, heat, and agitation.
B. Temperature, detergent, and fabric weight
❌ Incorrect. Temperature is part of the equation (it's heat), but detergent and fabric weight aren't the variables. The three are water, heat, and agitation.
C. Water, heat, and agitation
✓ Correct. Water + Heat + Agitation = Shrinkage. Add more of any variable and you increase the effect on your fabric and fades. Reduce them and you stay in control. This is the entire logic of raw denim care — everything else is just an application of it.
D. Dye, fiber, and spin speed
❌ Incorrect. Spin speed contributes to agitation, but dye and fiber are fabric properties, not wash variables. The three variables are water, heat, and agitation.
2. Why should you never put raw denim in the dryer?
A. It causes the selvedge edge to unravel
❌ Incorrect. The selvedge edge is self-finished and doesn't unravel in the dryer. The problem is the combination of heat, moisture, and agitation causing shrinkage and uniform fading.
B. It combines heat, moisture, and agitation simultaneously — causing shrinkage and flat, uniform fading
✓ Correct. The dryer applies all three damaging variables at once at their worst. It shrinks the fabric and produces flat, uniform color loss rather than the beautiful differential fading of wear patterns. It causes damage that cannot be undone. Always hang dry.
C. It removes the sanforization treatment
❌ Incorrect. Sanforization is a mechanical pre-shrinking process applied at the mill — it can't be "removed" by a dryer. The dryer's harm is shrinkage and uncontrolled fading, not any reversal of a mill treatment.
D. It causes indigo to permanently bond to the cotton core
❌ Incorrect. The opposite is true — the dryer causes indigo to release from the surface, not bond more strongly. The result is flat, uniform fading rather than the sharp wear-pattern fades that make raw denim special.
3. What do surfactants in detergent actually do?
A. They chemically bond to indigo and strip it from the fabric
❌ Incorrect. Surfactants don't selectively target indigo — they work on oils and dirt by forming micelles. Harsh detergents can disturb surface indigo as a side effect, which is why gentle formulations are preferred for raw denim.
B. They soften cotton fibers to prevent shrinkage
❌ Incorrect. Softening is what fabric softeners and conditioners do. Surfactants in detergent break water's surface tension and form micelles to lift dirt — they don't prevent shrinkage.
C. They create foam, which lifts dirt from the fabric surface
❌ Incorrect. Foam is largely cosmetic — air trapped in surfactant films. The actual cleaning happens at the micelle level, which is invisible. More foam does not mean more cleaning power.
D. They break water's surface tension and form micelles that surround and lift dirt
✓ Correct. Surfactant molecules have a split personality — one end loves water, the other loves oil and grease. They break water's surface tension so it fully penetrates fabric, and form micelles that surround dirt particles and carry them away in the rinse water. Detergent doesn't clean your jeans — water does. Detergent just makes water dramatically better at its job.
4. What is the recommended washing method for most raw denim?
A. Cold tub soak with gentle detergent, no agitation, hang dry
✓ Correct. The cold tub soak gives you maximum control over all three variables: no heat, no agitation, controlled soak time. Fill a tub with cold water, add a small amount of gentle detergent, submerge for 20–40 minutes without agitating, rinse twice, and hang dry. This is the method that best preserves your fades while getting the jeans clean.
B. Warm machine wash, gentle cycle, tumble dry low
❌ Incorrect. Warm water and tumble drying both apply heat — one of the three variables that causes shrinkage and fading. Never tumble dry raw denim, even on low.
C. Dry clean only
❌ Incorrect. Dry cleaning is not recommended for raw denim — the solvents used can damage the fabric and the indigo surface. A cold tub soak is the preferred method.
D. Cold machine wash, high spin, hang dry
❌ Incorrect. Cold water is correct, but high spin introduces significant agitation — one of the three variables that causes shrinkage and damages fades. Use the gentlest cycle available, not high spin.
← Previous: DU 301 | ↑ Denim University | Next: DU 303 →
By Eric Steffen
Founder / Maker
FITTED Underground
What I know about washing raw denim comes from years of personal experience and from advising hundreds of clients on how to care for their jeans. I've tested things. Some of the tests went well. Some of them were .. educational.
What I've found, after all of that, is that washing raw denim is less complicated than it may seem — but it does require understanding a few things about what's actually happening to your fabric when it gets wet. Once you understand the mechanics, the decisions become obvious.
The Equation
Here is the framework I use when thinking about washing raw denim:
Water + Heat + Agitation = Shrinkage
Each of those three variables contributes to the same outcome: the cellulose fibers in your cotton denim relaxing, contracting, and releasing indigo dye. Add more of any one variable and you increase the effect. Add all three at full intensity — hot water, high-spin cycle, then a dryer on high — and you will find out exactly how much your jeans can shrink.
The corollary: reduce any of those variables and you reduce the effect. This is the entire logic of raw denim care, and everything else in this article is just an application of it.
The Science: Why Cotton Shrinks and Indigo Fades
To understand what's happening when you wash your jeans, it helps to understand what cotton actually is at the molecular level — and what indigo dye is doing on the surface of it.
Why Cotton Shrinks
Cotton fiber is made almost entirely of cellulose — a natural biopolymer composed of long chains of glucose molecules. In their natural state, these cellulose chains are crinkled and coiled. During the manufacturing process, the fibers are mechanically pulled, stretched, and twisted to align them into yarn and then woven into fabric. That process introduces tension — the fibers are held in a stretched-out state that is not their natural state.
Here is the critical thing to understand: cotton fiber has memory. It remembers its original, more compact shape. And when it encounters heat, moisture, or mechanical agitation — or any combination of the three — it condenses back toward that memory. This is the molecular basis of shrinkage.
More specifically: cotton is hydrophilic, meaning it actively attracts water molecules. When cotton fiber gets wet, water penetrates the cellulose structure and breaks the hydrogen bonds that were holding the fiber in its stretched, manufactured state. The fiber swells — expanding up to 20–30% in width while barely changing in length. As it does, it pushes against neighboring fibers, tightening the weave. When the water is removed quickly — through a high-spin cycle or heat drying — the fiber contracts rapidly and locks into a more compact arrangement.
The three variables in the equation each accelerate this process: water penetrates the fiber and breaks the hydrogen bonds, enabling relaxation; heat increases the energy of the fiber molecules, causing them to shake more rapidly and break bonds faster — significantly accelerating shrinkage above about 104°F (40°C); agitation adds mechanical force, physically manipulating the fibers as they are in their loosened, water-swollen state and locking the contraction in place as they dry.
Selvedge denim — woven on vintage shuttle looms in a tight, dense weave — is actually somewhat more resistant to dramatic shrinkage than looser-woven fabric, because the tight weave gives the fibers less room to move. But resistance is not immunity. Raw (unsanforized) selvedge can shrink meaningfully. Sanforized selvedge has been pre-mechanically shrunk during production and will shrink much less in the wash — but it will still shrink if you apply enough heat and agitation.
Cotton has memory. Every wash is a negotiation between the fiber's stretched manufactured state and the compact shape it's trying to return to. Your job is to slow that negotiation down.
Why Indigo Fades
Indigo dye behaves differently from most dyes, and understanding why explains a great deal about both raw denim's appeal and its care requirements.
Most dyes are designed to penetrate deep into the fiber and bond chemically with the cellulose at a molecular level. Indigo does not. Indigo sits primarily on the surface of the cotton yarn — it coats the exterior of the fiber without fully penetrating it. This is why the inside of raw denim yarn is white: the indigo hasn't reached it. And this is why raw denim fades the way it does, developing those high-contrast, personalized wear patterns — whiskers at the thighs, honeycombs behind the knees, stacks at the ankle. The surface dye wears away first in areas of friction, revealing the white weft underneath.
This surface relationship also means indigo is sensitive to anything that disrupts the fabric surface: hot water (which makes the fiber swell and release dye), agitation (which creates friction that physically abrades the dye away), harsh detergents (which can chemically strip the surface coating), and heat drying (which bakes the dye out uniformly, producing flat, undifferentiated fading rather than the beautiful contrast of wear-pattern fading).
The goal when washing raw denim is to clean the fabric without stripping the surface indigo beyond what normal wear would remove. You want dirt out and dye in — as much as possible.
The Science: How Detergent Actually Works
Here is something most people have never thought about: detergent doesn't clean your clothes. Water does. What detergent does is make water dramatically better at its job.
The problem with plain water is surface tension. Water molecules are strongly attracted to each other, which causes water to bead up on surfaces rather than spreading and penetrating. On fabric, this means water can't fully wet the fibers and reach the dirt embedded in them.
Detergent contains molecules called surfactants — short for surface-active agents. A surfactant molecule has a split personality: one end (the "head") is hydrophilic, meaning it loves water. The other end (the "tail") is hydrophobic, meaning it hates water and loves oil and grease instead.
When surfactant is added to water, the hydrophobic tails try to escape the water by clustering together. They do this by forming tiny spherical structures called micelles — spheres with the oil-loving tails pointing inward and the water-loving heads pointing outward into the water. This formation also breaks the surface tension of the water, allowing it to spread and penetrate fabric fully.
When those micelles encounter dirt or oil embedded in your denim, the hydrophobic tails find something they like even more: the oils and greasy compounds in the dirt. The tails embed into the dirt particles, surrounding them. The water-loving heads on the outside pull the whole assembly — micelle plus trapped dirt — away from the fabric fiber and into suspension in the wash water. The dirt is now floating inside the micelle and is carried away when the water is rinsed out.
Detergent doesn't clean your jeans. Water does. Detergent just makes water dramatically better at its job — and the gentler the detergent, the less surface indigo gets disturbed in the process.
What this means for raw denim: detergent is effective precisely because it is designed to lift compounds from surfaces. The gentler the detergent and the colder the water, the less surface indigo gets disturbed. This is why Woolite Dark, a dedicated denim wash, and diluted Dr. Bronner's are preferred for raw denim — they use milder surfactant formulations that clean effectively without aggressive surface stripping.
One more thing: foam does not mean clean. The bubbles you see in soapy water are largely cosmetic — air trapped in surfactant films. The actual cleaning happens at the micelle level, which is invisible. Use less detergent than you think you need.
Sanforized vs. Unsanforized: Know What You Have
Before you wash your jeans for the first time, you need to know which of these you are dealing with.
Sanforized denim has been mechanically pre-shrunk during production — run through rollers and steam while under tension to release much of the stress built into the fibers during weaving. It will still shrink somewhat if exposed to heat and agitation, but the dramatic first-wash shrinkage is largely already done. Most raw denim — including FITTED Underground's ready-to-wear — is sanforized. You can wash it with considerably more confidence.
Unsanforized (shrink-to-fit) denim has had none of that stress released. It comes off the loom stiff and large, and it is designed to shrink significantly in the first wash — ideally to fit the wearer's specific body. Sizing up one to two waist sizes before soaking is standard practice. The first wash is a deliberate, managed event, not just a laundering. If you are not sure whether your denim is sanforized or not, check with the brand or retailer before washing. We cover this in full in DU 103: Sanforized vs. Shrink to Fit.
A note on stretch blends: if your raw denim contains any elastane or spandex — even at 2% — the shrinkage behavior becomes significantly less predictable. Treat stretch raw denim with particular caution: always cold water, always gentle, always air dry.
The Hierarchy of Washing Methods
Ranked from most to least control over shrinkage and fading:
1. The Tub Soak — Most Recommended
This is my preferred method and the one I recommend to most clients. It gives you the most control over all three variables in the equation: no heat, no agitation, a controlled soak time.
Fill a bathtub or large basin about four inches high with cold water. Add a small amount of a gentle detergent — Woolite Dark, a product specifically formulated for denim, or a few drops of diluted Dr. Bronner's. Mix the detergent into the water with your fingers until you see some suds. Then submerge your jeans and let them soak for 20 to 40 minutes, depending on how dirty they are. You don't need to scrub or agitate — the detergent and water will do the work.
After the soak, drain the tub and rinse the jeans. Expect to do at least two rinses — the first will still run dark with indigo and loosened dirt. Rinse until the water runs mostly clear. Wring gently — don't twist — and hang to dry.
2. Hand Washing in a Basin — Good
Same principle as the tub soak but in a smaller container. Works well for spot-treating or when you want to focus on a specific area. Slightly more hands-on, which means slightly more agitation — be gentle.
3. Machine Washing — Acceptable, with Caveats
You can put raw denim in a washing machine. The equation still holds, so reduce all three variables as much as the machine allows: cold water, gentle cycle, and — critically — air dry afterward, never the dryer.
Turn your jeans inside out before loading. This shifts the agitation and friction away from the outer dyed surface. Wash alone or with other dark items only — fresh raw denim bleeds significant indigo in the first several washes. Use less detergent than you think you need.
4. Spot Cleaning — Underused and Excellent
For minor dirt or stains, a full wash is almost always overkill. A damp cloth, a soft toothbrush, and a tiny amount of diluted mild soap can address most everyday marks without introducing your whole jean to water, heat, and agitation. Extend the time between full washes and the fades you earn through wear will be sharper and more beautiful.
A Word on Vinegar
Adding white vinegar to your wash helps preserve indigo color. This is not a myth. Indigo and sulfur dyes release pigmented mineral compounds when washed, and the mild acidity of vinegar neutralizes these minerals and slows the release. It also acts as a gentle fabric softener. Add about a cup of distilled white vinegar to your tub soak or washing machine — the vinegar smell dissipates completely as the jeans dry. It is worth doing on the first wash especially. Note, however, that it will slightly slow down the development of sharp fades, since it's fixing some dye that might otherwise wear away unevenly through normal wear. A minor trade-off that's worth it for most people.
Drying: The One Rule Written in Stone
If there is one absolute rule in raw denim care, it is this: do not put your jeans in the dryer.
The dryer combines all three variables in the equation at their worst: wet fibers plus sustained high heat plus mechanical tumbling. It will shrink your jeans. It will fade them — not the beautiful differential fading of wear patterns, but flat, uniform color loss across the whole garment. It will damage the elastane in any stretch blend. And it will do all of this in ways that cannot be undone.
The only exception is intentional shrinkage. If you have a pair that is genuinely too large, you can use the dryer deliberately — but check every ten minutes. Wet denim in a hot dryer can shrink dramatically and fast.
For normal care: hang dry. Flip your jeans inside out, or pull the front pockets out so they are exposed to air. Hang in your bathroom overnight with the fan on. By morning, they should be dry or nearly there.
The dryer is the one place raw denim should never go. Heat, moisture, and agitation all at once — and damage that can't be undone. Hang dry. Always.
One technique worth knowing: hang them while still slightly damp and wear them for the last hour or so of drying. The jeans will relax and settle back to your body's shape as the remaining moisture evaporates. This is particularly useful after the first wash, when the fibers are at their most pliable.
How Often Should You Wash?
Less often than you think. Raw denim's reputation for infrequent washing is not just denim-head posturing — it has real basis in the chemistry and in the care of your fades.
Every wash, however gentle, removes some indigo from the surface. Wear-pattern fading develops because different areas of the jeans experience different levels of friction during wear — the dye wears away faster in the high-contact zones, creating contrast against the darker areas. Frequent washing introduces a competing source of fade: uniform chemical and mechanical removal that blurs the contrast rather than sharpening it.
There is no universal rule about how long to go between washes. Use your judgment: does it smell? Is there visible dirt or staining that spot cleaning won't address? Then wash. Otherwise, air them out between wears and spot clean as needed.
What I tell clients: trust your nose more than the calendar.
Washing Method Summary
| Method | Shrinkage Risk | Fade Risk | Recommended? |
|---|---|---|---|
| Cold tub soak | Very low | Low | ✓ Best method |
| Hand wash, cold | Low | Low–moderate | ✓ Good |
| Machine wash, cold, gentle | Moderate | Moderate | ✓ Acceptable |
| Spot cleaning only | None | None | ✓ Underrated |
| Dry cleaning | Low–moderate | Moderate | Not recommended |
| Machine wash, warm or hot | High | High | Avoid |
| Machine dryer, any heat | Very high | Very high | Never (unless intentional) |
Raw denim care is not complicated. The equation is simple. Know which side of it you want to be on, and wash accordingly. The rest is just patience — and the jeans will take care of the rest.
What Comes Next
Now that you know how to wash without destroying your fades, the next question is how those fades actually develop — the chemistry and physics of indigo wearing away from cotton in patterns specific to your body and your life. That's DU 303: How Does Raw Denim Fade?
← Previous: DU 301 — Environmental Considerations of Raw Denim | Next: DU 303 — How Does Raw Denim Fade? →
Core Curriculum
Complete the core curriculum by reading these essential classes.
- DU 101 — What is Raw Denim?
- DU 102 — What is Selvedge Denim?
- DU 104 — Denim Weight Explained
- DU 201 — How to Buy Your First Pair of Raw Denim Jeans
- DU 204 — How Much to Spend on Raw Denim
- How It Works — FITTED Underground
Eric Steffen is the founder of FITTED Underground, a custom jeans and raw denim workshop at 108 Bayard Street in Williamsburg, Brooklyn. He has been making jeans by hand since 2014. Denim University is his attempt to share everything he's learned — about the history, the craft, and the culture behind the world's most enduring garment.
