Nylon, Polyester, or Cotton: How to Pick a Flag Material

There is no best flag material. There is a material that matches your wind, your pole, and what the flag is for. Get that match right and a flag lasts as long as it reasonably can. Get it wrong and you replace it twice as often, or you buy something heavier than your pole was built to carry.

Here is how the four main flag materials actually differ.

Nylon: the default, and usually the right one

What it is

Most outdoor flags sold in the United States are nylon, and there is a good reason. Nylon is light. A nylon flag will fly in a breeze so slight that a heavier flag would hang limp against the pole. If you care about how the flag looks on an ordinary day, that matters more than any spec on a sheet.

Typical outdoor nylon flag bunting is 200 denier, which is a measure of yarn weight. It takes dye well, which is why nylon flags have the most saturated color. It dries fast, which matters more than people expect: a flag that sheds water quickly spends less time heavy and abrading against itself.

Rain, specifically

Nylon sheds water instead of holding it. Rain beads on the finish and runs off, and the flag is light enough that whatever it does pick up dries in the next hour of wind. A nylon flag can stay up through a storm and fly properly the next morning instead of hanging against the pole in a wet rope.

That is the case for nylon in a wet climate. If your site gets a lot of rain and only moderate sun, nylon will usually outlast the heavier material that looks tougher on a spec sheet.

Choose nylon when

You are flying at a home, an office, a school, or any typical location with normal wind. You want strong color. You want the flag to actually fly rather than hang.

Think twice when

You are on a coastal site, a ridge, a high-rise, or anywhere with steady heavy wind. Nylon will fly beautifully there. It will also wear out faster. Hard, constant sun is the other case. Nylon is less resistant to ultraviolet light than polyester is, so a south-facing pole with nothing shading it is where the heavier material earns its weight.

Browse nylon US flags.

Polyester: for wind

What it is

Heavy-duty outdoor polyester is a different animal. It is built from two-ply spun polyester with an open weave, and the open weave is the whole point. Air passes through the fabric instead of pushing against it, which reduces the load on the flag and on the pole. It is the most durable material we sell for outdoor use.

The tradeoffs

Polyester is heavier, so it needs more wind to fly properly. It has a coarser, more textured look up close, closer to cotton than to nylon. And on a light-duty residential pole, the extra weight is not free. If your pole came with a flag size recommendation, a heavier flag at that size puts more strain on the shaft.

It holds water, which is not the same as absorbing it

This one gets explained backwards constantly. The polyester fiber itself barely absorbs anything. It absorbs less than nylon does. The water is not in the fiber, it is in the yarn. Two-ply spun polyester is spun from short fibers with a fuzzy surface, so water lodges in the spaces between them instead of running off, and the flag weighs roughly twice what nylon does, so there is twice as much of it to dry. A polyester flag can still be damp a day after the rain stopped while the nylon flag on the next pole dried by breakfast.

A flag that stays damp will mildew. Nothing is eating the polyester and nothing is going to. The mildew grows in the dirt the wet fabric is holding, which is why conservators treat soiling as the real risk factor: dirty fabric supports mildew at humidity that clean fabric shrugs off. The practical version is that a polyester flag in a wet climate needs washing more often than people expect, and washing it is usually the entire repair.

Choose polyester when

Your flag is in a genuinely windy location, you are replacing nylon flags faster than you would like, or the installation is commercial or institutional and you want the longest service life you can get.

Browse polyester US flags.

Cotton: for ceremony, and for one practical reason

What it is

Cotton is the historical material. It has a low sheen and a soft drape that photographs beautifully and looks right in a ceremonial setting. It is not an outdoor material in any modern sense. Cotton absorbs water, holds it, fades in sun, and mildews.

Indoor and ceremonial display

The first place cotton is still exactly right. Nothing beats how it hangs.

Retirement by burning

The second. The Flag Code says a worn flag should be destroyed in a dignified way, preferably by burning. That was written when flags were cotton. Burning nylon and polyester produces toxic fumes, which is why a traditional burning ceremony is only appropriate for a 100 percent cotton flag.

If you specifically want a flag that can one day be retired by fire the traditional way, cotton is the material that allows it. More on that in repair it or retire it.

The pros nobody mentions

It does not glare. Nylon is lustrous, and under gym lighting, stage lighting, or a camera flash it flares into a bright patch that blows out in every photograph. Cotton stays matte. If the flag is going to stand behind a podium or show up in pictures, that one property is the whole argument.

It has enough body to hang. Indoor air is still air, and a light synthetic flag goes slack and clings to the pole, so what you see is the pole. Cotton falls into folds on its own.

It carries fringe properly. Cotton and gold fringe are close enough in weight that the fly end hangs square. Heavy fringe on a light flag drags the bottom edge out of shape.

The cons nobody mentions

Cotton mildews indoors. This is the one that catches people, because indoors feels like the safe place. Cotton pulls moisture out of room air quickly and gives it back slowly, and in still air above roughly 80 percent relative humidity, mildew will grow on it. A cotton flag in a closed case, in a building with the air conditioning off, through a humid summer, is that exact situation.

Store it rolled or flat, not folded. This is about long-term storage and not about the ceremonial fold. Museum practice for flags is flat in acid-free tissue or rolled on a tube, because a crease held in cotton for years becomes the line the flag gives out along.

Indoor light still counts. Fluorescent tubes and daylight through a window both carry ultraviolet. The damage shows up as brittleness and a shift in color, not only as fading, and it accumulates. A cotton flag on permanent display next to a window is on a clock.

Browse cotton US flags.

Rayon: indoor and ceremonial only

Rayon is an indoor and ceremonial material. It behaves and shines like silk, and it takes appliqué and embroidery beautifully. It is also delicate and requires care. You will see it on premium indoor sets and hand-finished ceremonial flags, never outdoors. See Appliqué & Embroidery for how it is used.

Flag material comparison: nylon, polyester, and cotton

Lock stitch or chain stitch: the spec that is not on the label

Two flags can match on material, size, and finish and still be built with two different stitches. The difference does not show up in the showroom. It shows up the first time a thread breaks.

Lock stitch

A lock stitch uses two threads. One comes off the spool through the needle, one comes off the bobbin underneath, and the machine locks them together inside the fabric at every single stitch. Each stitch stands on its own. Break one and you have one broken stitch. The stitches on either side of it carry on.

That is what you want on anything that flies. The fly end of an outdoor flag is in constant motion and threads there break, which is normal and always has been. The only question is whether a broken thread stays a broken thread or becomes a failed hem. A 3 FT x 5 FT flag sewn with a lock stitch holds together around the damage long enough for you to see it and get the flag repaired. A lock stitch is slower to sew and uses more thread than a chain stitch does.

Chain stitch

A chain stitch uses one thread looped back through itself, like a crochet chain. It is quick to sew and it uses less thread. It also behaves exactly like a crochet chain: pull the right end and the whole row comes out. That is not a flaw in the stitch, it is the design. It is why a flour sack opens in one pull.

Indoors, none of that matters. The flag hangs in still air, nothing is working the seam, and the stitch will outlast the fabric around it.

Outdoors it matters a great deal. Wind guarantees broken threads at the fly end. A chain stitch turns the first one into an open hem, and an open hem on a flying flag becomes a shredded flag fast, because the loose fabric starts whipping and takes the rest with it.

The short version

If the flag is going to fly, buy the lock stitch. If it is going to stand in the corner of an office, chain stitch is fine. And if you are writing a spec for an outdoor flag, put the stitch in the spec. It is the easiest line to leave off the sheet and one of the few that changes how long the flag lasts.

“All-weather flag” is a legal term, not a slogan

Worth knowing if you are writing a spec. Section 6 of the US Flag Code says the flag should not be displayed in inclement weather, except when an all-weather flag is displayed. The phrase comes from the statute itself.

In practice it means a synthetic flag built to take rain, which is nylon or polyester, not cotton. If your organization wants to fly in all weather and still follow the Code, the flag material is the compliance step.

Two things that matter more than flag material

Honest answer, from a shop that repairs flags all day: material is the third most important decision.

What the flag touches

A flag that brushes a gutter, a wall, a tree limb, or a wire will shred in weeks regardless of what it is made of. A non-tangle rod and correct bracket placement do more for flag life than any fabric upgrade.

Rotation

Two flags alternated will outlast three flags flown to death one at a time. Neither one is ever soaked, dried, and re-soaked without a break. We go into this in how long a flag lasts.

Sizing, briefly

Material and size interact. A larger flag in a heavier material is a meaningfully larger load on the pole. Flying a flag larger than the pole’s recommended size can also void the pole manufacturer’s warranty.

If you are flying two flags on one pole, the combined square footage should not exceed the recommended size for that pole. Our guide to choosing the right size flag for your flagpole has the chart.

Related reading

• Anatomy of a flag: every part, named
• US flag etiquette: what the Flag Code actually says
• Repair it or retire it: how to tell when a flag is done

Not sure which one fits your site? Tell us the pole height, the location, and how exposed it is, and we will tell you what we would fly there. Contact us.

Sources

• 4 U.S.C. § 6, Time and occasions for display (all-weather flag provision) · Cornell Legal Information Institute · law.cornell.edu
• 4 U.S.C. § 8(k), Respect for the flag · Office of the Law Revision Counsel · uscode.house.gov
• U.S. Flag Myths, FAQs & Terminology · The American Legion · legion.org
• Mold and Mildew Growth on Textiles · Smithsonian Museum Conservation Institute · mci.si.edu