Mothball Ingredients: Naphthalene vs Paradichlorobenzene

If you’re trying to protect stored clothes or linens, the first question is usually the mothballs definition, because the label wording matters. Before you buy or use any product, you need to know which ingredient is inside and what risks come with it. This guide breaks down the two main mothball ingredients, how they work, and how to handle them safely.

For more help, see our Naphthalene and Mothballs: Ingredients, Vapor Action, Risks guide.

What Mothballs Are and What They’re For

A plain-English definition of mothballs

Mothballs are pesticide products made to release a strong vapor that helps protect stored fabrics and materials from moths and other pests. They are not meant to be sprayed or rubbed onto clothing. Instead, the product is packed into a small solid form, placed inside a storage space, and allowed to release vapor over time. The vapor fills the enclosed area enough to discourage pests from feeding or nesting on vulnerable items like wool, fur, and some stored textiles.

Check the label for the active ingredient.
Place the product inside sealed storage with the items.
Refresh the product when the odor fades.

Why people use them in storage spaces

People use mothballs when items sit for months in basements, attics, closets, or garment bags that do not get regular cleaning and airflow. The goal is to keep pests away from fibers that can be damaged by larvae. Mothballs work best when the storage space is closed, because the vapor needs to stay concentrated around the items.

Store seasonal clothing in airtight totes or vacuum-sealed bags (with ventilation as recommended for the bag type).
Put mothballs only in the enclosed storage area, not on open shelves.
Keep storage away from living spaces where strong odors spread.

Common meaning and common misconceptions

A common misconception is that mothballs “deodorize” a room. They are pesticide products, and the odor is a sign of vapor release, not a cleaning effect. Another misconception is that they can be placed loosely and still work well. Loose placement in a drafty closet reduces vapor concentration, so protection drops.

Treat mothballs as pesticides, not air fresheners.
Use sealed storage to keep vapor where it belongs.
Replace when odor weakens, because protection depends on vapor release.

The Two Main Chemicals: Naphthalene and Paradichlorobenzene

How the two ingredients differ

Most mothballs contain either naphthalene or paradichlorobenzene as the active ingredient. These chemicals differ in chemical structure, how they smell, and how their vapor behaves in enclosed storage. In practice, people often notice stronger or longer-lasting odor depending on which ingredient a product contains, and that odor is tied to vapor release rate.

Look for “naphthalene” or “paradichlorobenzene” in the active ingredient line.
Use the same storage approach for either one, because vapor concentration is what protects items.
Compare safety warnings on the label, since both are hazardous if mishandled.

Which type is more common today

Both ingredients show up in mothball products, but paradichlorobenzene is commonly sold in certain modern mothball formats, including some blocks and sealed dispensers. Naphthalene has long been used in mothball products and still appears in many formulations. Your best way to know is to read the active ingredient on the packaging, not rely on appearance or smell alone.

Purchase only products with clear active ingredient names.
Confirm the ingredient before use, even if the product looks similar to an older one.
Follow the label directions for amount and placement.

Why some products are labeled only by odor or use

Some products get marketed with trade names or descriptions, and shoppers assume odor equals effectiveness. However, “odor” does not tell you the active ingredient, and it does not tell you the safety requirements that apply. Always find the active ingredient section and identify whether the product contains naphthalene or paradichlorobenzene.

Find the “Active ingredient” line on the label.
Avoid guessing based on how strong the smell seems.
Use the manufacturer’s recommended amount for the storage volume.

How Mothballs Work in Real Life

Why they seem to shrink over time

Mothballs shrink because the solid ingredient leaves the container as vapor. As it vaporizes, the visible mass decreases. This is normal behavior, and it is also why protection depends on keeping the vapor contained around stored items. When the solid has shrunk a lot and odor becomes weak, vapor release slows and pest protection drops.

Expect gradual size reduction during storage.
Keep the product in the correct container or location specified by the label.
Plan to refresh the product when the odor fades noticeably.

Sublimation: turning from solid to vapor

Sublimation is the process where a solid changes directly into vapor without becoming a liquid first. Mothballs are designed to do this under typical indoor temperatures, which lets them release vapor into the storage area. That vapor phase is what creates a pest-repellent environment for stored fabrics.

Place mothballs in a sealed container or tote with your items.
Do not place them where vapor can escape into open air.

Keep storage temperatures within normal indoor ranges per label guidance.

Why that vapor helps repel pests

The vapor creates conditions that deter moth larvae and other pests that damage natural fibers. Pests rely on feeding on materials like wool, fur, and some stored textiles. In an enclosed space, the vapor concentration becomes high enough to discourage that activity until the stored items are removed.

Use airtight storage so the vapor concentration stays high.
Keep items clean and dry before packing.
Replace mothballs when vapor release declines.

Safety, Fire Risk, and Handling Basics

Why mothballs should never be treated like deodorizer

Mothballs are pesticide products. Using them like a room deodorizer puts vapor into areas where people, especially children and pets, breathe it. That increases exposure without providing the concentrated, controlled storage environment mothballs require. The strongest safety approach is to place mothballs only in sealed storage for protected items.

Never hang or place mothballs in open closets.
Never use them in bathrooms, bedrooms, or kitchens for smell control.
Keep the product out of reach and away from frequent access areas.

Flammability and storage precautions

Many mothball products can pose a fire hazard. Keep them away from heat, flames, sparks, and hot equipment. Do not store them near furnaces, water heaters, stoves, or anything that generates ignition sources. Follow label storage and disposal instructions, since packaging and formulation can vary.

Store mothballs in their original container when possible.
Keep the container in a cool, dry, stable location away from ignition sources.
Keep mothballs off shelves and floors where they can be knocked or exposed.

Keeping them away from children, pets, and food areas

Mothballs are toxic if swallowed and harmful if misused. Store them where children and pets cannot reach them, and never store them alongside food, pet food, dishes, or cookware. In homes with pets, use sealed totes with a latch or lid that cannot be easily opened.

Use lockable storage or high cabinets for the unopened product.
Keep mothball pieces sealed in the storage tote, not loosely in the room.
Keep packed food items in separate cabinets, never in the same tote or area.

Water, Moisture, and Disposal Questions

What happens if mothballs get wet

If mothballs get wet, the product can become harder to manage and may stop releasing vapor effectively. Water can also cause contamination risk for nearby surfaces and stored items. Even if the mothballs still contain active ingredient, wet contact can reduce performance and create a cleanup problem.

Keep mothballs dry during storage.
If they get wet, remove them, bag them, and move them away from stored fabrics.
Replace with a dry product if the label allows replacement after exposure to moisture.

Why they do not simply dissolve like salt

Mothballs are solids designed for sublimation, not dissolution in water. They do not behave like table salt, which breaks down as it absorbs water. Instead, the active ingredient leaves as vapor under the conditions mothball formulations are meant for. Water may affect the surrounding storage environment, but it does not turn the product into a harmless dissolved substance.

Do not assume water will “wash away” the active ingredient.
Treat wet mothballs and residues as contaminated.
Clean up nearby surfaces carefully using protective gloves.

Safe disposal and cleanup considerations

Disposal rules depend on your local hazardous waste program and the product’s exact formulation. In general, you should not toss mothballs into household trash without checking local guidance, especially where local facilities require special handling. Cleanup should focus on containing residue, avoiding skin contact, and preventing vapor exposure during disposal.

Bag leftover mothballs and any contaminated materials in a sealed plastic bag.
Keep the bag out of living areas until you can follow local disposal instructions.
Use gloves for cleanup, and wipe the storage area after removing the product (per label guidance).

History, Uses, and Modern Alternatives

A brief history of mothball use

Mothballs became popular as a practical way to protect stored textiles from moth damage. For decades, people relied on naphthalene and then expanded to products using paradichlorobenzene. As safety awareness grew, labels and storage instructions became more specific, emphasizing controlled use and keeping the chemicals away from living spaces.

Traditional mothball use focused on enclosed storage for seasonal textiles.
Active ingredient names on labels became more important as products diversified.

Modern consumers often pair chemical protection with better storage containers.

Traditional and current uses

Traditionally, mothballs were used in closets and storage areas where fabrics sat for long stretches. Today, many people still use them for wool coats, winter hats, and fur-lined items, especially when storage is sealed. The key difference now is that people more often store items in airtight totes or sealed garment bags to concentrate protection and reduce odor spread.

Use mothballs only in sealed storage for textiles you want protected.

Pair chemical protection with clean, dry storage habits.
Follow the label amount for the size of the storage container.

When to choose non-chemical storage options instead

If you want to avoid pesticide vapor in your home, switch to non-chemical methods that block pests without releasing hazardous chemicals. Cold storage, strict cleanliness, and physical barriers can work well for many items. Vacuum-sealed bags and airtight containers are strong options, especially for synthetic fabrics and items that do not need chemical treatment.

Use airtight containers or vacuum-sealed bags for seasonal clothing.
Remove items from storage periodically and inspect for damage.
For natural fibers, store them sealed after thorough cleaning, then add moth protection only if you have a real pest risk.

Choosing the Right Product and Reading the Label

How to identify the active ingredient

The active ingredient line tells you which chemical is inside the product. Look for naphthalene or paradichlorobenzene in the active ingredient section, not just the product name. If the label lists only “moth repellent” or relies on smell descriptions, find the ingredient details or choose a product with clear active ingredient wording.

Locate “Active ingredient” on the label.
Confirm the name is either naphthalene or paradichlorobenzene.
Follow the label for how many mothballs to use per container size.

What warning labels mean

Warning statements are there because the chemicals can be hazardous by inhalation, contact, or ingestion. Read the safety section and treat the instructions as part of the product’s performance, since improper use spreads vapor into places it should not go. Pay close attention to guidance about children and pets, ventilation, and storage location.

Follow any “keep away from children” and “do not place in living areas” warnings.
Use gloves if handling broken pieces or residue.
Store only in enclosed containers where the label says to use the product.

When a pest problem needs a different solution

Mothballs protect stored items from damage, but they do not fix an active infestation in your home. If you see adult moths, larvae, or webbing in rugs, closets, or pantry areas, the problem needs cleaning and targeted pest control steps. Start with source removal, vacuuming, washing textiles, and then use moth protection in storage only as part of prevention.

If you find larvae or webbing, treat the infested area first.
Wash washable fabrics and vacuum cracks, corners, and storage areas thoroughly.
Use mothballs in sealed storage after the source is addressed.

Frequently Asked Questions

What is the definition of mothballs?

Mothballs are pesticide products made to release a strong vapor that helps protect stored fabrics and materials from moths and other pests.

What are mothballs made of?

Most mothballs contain either naphthalene or paradichlorobenzene as the active ingredient, along with other ingredients that help form the product.

Do mothballs dissolve in water?

They are not meant to dissolve in water in normal use; they gradually disappear mainly by sublimation, where the solid changes into vapor.

Are mothballs flammable?

Yes, they can pose a fire hazard and should be kept away from heat, flames, sparks, and hot storage areas.

What is the difference between naphthalene and paradichlorobenzene mothballs?

Both are used as mothball ingredients, but they differ in chemical structure, odor, and vapor behavior. Product labels should identify which one is present.