How to Use Desiccants for Moisture Protection
THE COMPLETE GUIDE TO
DESICCANTS
Everything you need to know about silica gel, container desiccants, and moisture protection so you can keep products dry during shipping and storage.
WHY MOISTURE PROTECTION MATTERS
Moisture is one of the most common and costly causes of product damage during shipping and storage. Electronics corrode, pharmaceuticals degrade, leather goods mold, and metal parts rust when humidity inside a package exceeds what the product can tolerate. The damage is often invisible until it is too late.Desiccants are a simple, low-cost solution. Placed inside a package, container, or storage area before it is sealed, they absorb excess moisture from the air and keep the interior humidity within a safe range for the product. Benchmark has supplied desiccants and protective packaging to warehouse, manufacturing, and shipping operations across Ohio and the Midwest since 1946.
Silica Gel Packets
OCEAN AND CONTAINER FREIGHT
Hanging Container Desiccants
VERY HIGH HUMIDITY ENVIRONMENTS
Calcium Chloride Desiccants
METAL PARTS AND CORROSION RISK
Desiccants + VCI Packaging
LONG-TERM OR MONITORED STORAGE
Silica Gel with Humidity Indicator
WHAT IS A DESICCANT?
The most widely used desiccant for shipping and storage is silica gel. Silica gel works by adsorption: water molecules in the surrounding air are attracted to the surface of the silica gel granules and held there, pulling humidity out of the enclosed space. The gel itself does not get wet or dissolve. It simply holds the moisture in place until it is recharged or replaced.
Desiccants are a passive form of moisture control. They do not require power, activation, or monitoring during normal use. Drop the packet into the package before you seal it and it works automatically for the duration of shipping or storage.
ADSORPTION VS. ABSORPTION
Silica gel works by adsorption: water molecules cling to the surface of the granules without the material changing state. Calcium chloride works by absorption: it chemically takes up the water and liquefies in the process. Both remove moisture from the air, but they behave differently and are not interchangeable for all applications.
TYPES OF DESICCANTS
The right desiccant depends on the moisture level you are dealing with, the size of the space, and whether the product will be in short-term transit or long-term storage.
SILICA GEL PACKETSThe standard desiccant for packaging and storage. Silica is one of the most abundant materials on Earth, which makes these packets highly cost-effective. They are sized in units, work across normal temperature and humidity ranges, and can be recharged for reuse. Silica gel performs best under standard atmospheric conditions rather than extreme heat or very high moisture environments.
BEST FOR: Electronics, pharmaceuticals, leather goods, food products, and any item shipped or stored in normal indoor conditions
HANGING CONTAINER DESICCANTSLarge-format desiccant bags designed to hang inside shipping containers, railcars, and barges using a clip-on hook. They absorb the much larger volume of moisture that accumulates in long-distance freight containers, where temperature swings cause condensation on interior walls and ceiling surfaces. A single hanging desiccant handles significantly more moisture than a standard packet.
BEST FOR: Ocean freight, intermodal shipping, railcar shipments, and long-distance container loads
CALCIUM CHLORIDE DESICCANTSCalcium chloride absorbs moisture at a significantly higher rate than silica gel and is used when create dealing with very high humidity or liquid water that needs to be removed from the environment. Unlike silica gel, it liquefies as it absorbs moisture, so it is contained in a drip tray or absorbent pouch to keep liquid away from the product. It cannot be recharged.
BEST FOR: High-humidity storage, container shipments with extreme moisture risk, and applications where silica gel alone is not sufficient
WHAT DESICCANTS PROTECT AGAINST
Moisture damages products in different ways depending on what they are made of and how long they are exposed. Desiccants address all of these by keeping relative humidity inside the package below the threshold that triggers damage.
Metal parts, tools, fasteners, and hardware oxidize when humidity rises inside a package. Desiccants keep moisture levels too low to sustain the chemical reaction that produces rust. For high-value metal components, desiccants are often paired with VCI packaging for added protection.
Organic materials including leather, fabric, paper, and wood are susceptible to mold growth when humidity stays elevated. Desiccants keep relative humidity low enough to inhibit mold and mildew formation during shipping and storage.
Moisture causes electrical shorts, oxidation on contacts, and corrosion on circuit boards. Desiccants are standard in electronics packaging to protect components between manufacturing and end use, especially for export or long-distance shipments.
Many medications and supplements are sensitive to humidity, which can affect potency, appearance, and shelf life. Desiccants are widely used in pharmaceutical packaging to protect product integrity through distribution.
When a container moves through different climates, warm humid air condenses on cooler surfaces as temperature drops. This is sometimes called container rain in ocean freight. Hanging desiccants absorb the excess moisture before condensation can form and drip onto cargo.
Food products, powders, and granular materials can clump, cake, or spoil when humidity rises. Desiccants help maintain the dry interior environment needed to keep these products free-flowing and shelf-stable through the supply chain.
HOW TO SIZE AND USE DESICCANTS
Getting the sizing right is the most important step. Too little and humidity is not adequately controlled. Too much adds unnecessary cost. Here is how to approach it.DETERMINE YOUR INTERIOR VOLUME
Measure the interior dimensions of the package or container in inches and calculate the cubic footage. Length × Width × Height, then divide by 1,728 to convert cubic inches to cubic feet. This is the number you will use to size your desiccant.
SEAL THE PACKAGE TIGHTLY
A desiccant can only control the humidity of the air that is sealed inside with it. A loosely closed box will continuously pull in fresh humid air from outside, exhausting the desiccant much faster. For maximum effectiveness, seal the package or use a sealed poly bag inside the outer corrugated box.
APPLY THE SIZING FORMULA
As a general guideline, 1.2 units of silica gel will protect approximately 1 cubic foot of interior space under standard shipping and storage conditions. A small silica gel packet is typically 1/3 unit; a larger packet is 2 units. Increase the amount for highly sensitive products, humid climates, or packages that are not tightly sealed.
KNOW HOW LONG THEY LAST
Under normal conditions, silica gel packets are effective for 4 to 12 months. The actual duration depends on how humid the environment is and how well the package is sealed. A tightly sealed poly bag extends effectiveness significantly compared to a loosely closed corrugated box.
PLACE INSIDE BEFORE SEALING
Place the desiccant inside the package before sealing, not outside. For large corrugated boxes, distribute packets near the top and bottom. For sealed poly bags, one packet placed anywhere inside the enclosure is typically sufficient for smaller packages. Do not place packets directly on food or pharmaceutical products; position them alongside the product instead.
USE INDICATOR PACKETS FOR LONG-TERM STORAGE
Standard silica gel gives no visible signal when it is saturated. For long-term storage where packages cannot be opened regularly, use indicator packets that change color when the desiccant is approaching saturation, so you know when to replace it without opening the package.
RECHARGING AND REPLACING DESICCANTS
Silica gel can be recharged and reused, which makes it a more economical long-term option for operations that handle the same products repeatedly. To recharge, heat the packets to 245°F (118°C) for approximately 16 hours. This drives the absorbed moisture back out of the granules and restores their capacity.
Do not overheat: temperatures above this threshold can damage the silica gel and, at high enough temperatures, can ignite the paper packaging surrounding the granules. Low and slow is the correct approach.
In most shipping and distribution applications, silica gel packets are discarded when the package is received rather than recharged, since the per-packet cost is low and recharging requires dedicated time and equipment. For operations using desiccants in reusable packaging or long-term storage programs, building recharging into the routine makes sense.
Calcium chloride desiccants cannot be recharged. They are single-use and should be disposed of once saturated. The liquid byproduct should be handled and disposed of safely and not poured down drains unless local regulations permit it.
DESICCANTS VS. VCI PACKAGING
For operations shipping or storing metal parts, the choice between desiccants and VCI (Volatile Corrosion Inhibitor) packaging is a common one. They are not competing solutions. They address the problem differently and work best together.
Desiccants work by reducing the amount of moisture in the air inside the package. Lower humidity slows corrosion and mold growth, but does not actively prevent it at the metal surface. A desiccant alone may not stop corrosion if humidity still exceeds the threshold for the metal involved. They are effective across a wide range of products and are not specific to metal.
Works on: All products sensitive to humidity, including electronics, leather, pharmaceuticals, food, and metal.
Limitation: At very high humidity, capacity may be exceeded before the desiccant is replaced or recharged.
.jpg)
VCI packaging releases molecules that form a thin protective layer on metal surfaces, actively blocking the electrochemical reaction that causes rust. VCI protects metal even at humidity levels that would still cause some corrosion without it. It is specific to metal surfaces and does not provide moisture control for non-metal products.
Works on: Metal surfaces only. Does not control moisture levels for other product types.
Best approach: Use both together for maximum protection. See our VCI packaging guide for details.
USE BOTH FOR MAXIMUM PROTECTION ON METAL PARTS
For high-value metal components, using VCI packaging together with desiccants provides both active corrosion protection and passive moisture control. This combination is the most effective approach for metal parts shipped over long distances or stored for extended periods.
HOW TO CHOOSE THE RIGHT DESICCANT
Use this table as a starting point. If you are unsure which product fits your application, contact a Benchmark rep for a recommendation.| SITUATION | DESICCANT TYPE | NOTES |
|---|---|---|
| Standard shipping and storage | Silica gel packets | Size based on interior cubic footage; 1.2 units per cubic foot is a reliable starting point |
| Ocean freight or intermodal containers | Hanging container desiccants | Clip-on hook hangs inside the container; absorbs large moisture volumes from condensation |
| Very high humidity or moisture-heavy environments | Calcium chloride desiccants | Higher absorption capacity; single-use only; liquid byproduct requires containment |
| Metal parts, tools, or hardware | Silica gel + VCI packaging | Desiccant controls humidity; VCI actively prevents corrosion at the metal surface |
| Long-term storage, packages not opened regularly | Silica gel with humidity indicator | Indicator changes color when packet nears saturation; no need to open to check |
| Pharmaceuticals or food products | Silica gel packets | Do not place directly on the product; position alongside it; confirm food-safe or pharma-grade spec if required |
| Reusable packaging or high-volume reuse programs | Rechargeable silica gel | Recharge at 245°F for 16 hours; calcium chloride cannot be recharged |
COMMON QUESTIONS
Answers to the questions we hear most about desiccants and moisture protection.
What does a desiccant actually do?
It absorbs moisture from the air inside a sealed package or container, keeping relative humidity low enough to prevent damage to the product. It does not cool, ventilate, or treat the product directly.
How many desiccant packets do I need?
As a starting point, use 1.2 units of silica gel per cubic foot of interior volume. Adjust up for highly sensitive products, very humid environments, or packages that are not tightly sealed.
Are silica gel packets safe?
Silica gel itself is non-toxic, but packets are marked "Do Not Eat" because silica used for desiccant purposes may contain trace amounts of other materials, and in the body the granules can cause irritation to mucus membranes, stomach discomfort, and a choking or obstruction risk in small children as the granules swell when they absorb moisture. Keep packets away from food contact and out of reach of children.
Can desiccant packets be reused?
Yes. Silica gel can be recharged by heating to 245°F for about 16 hours to drive out the absorbed moisture. Do not overheat. In most shipping applications, packets are discarded at delivery since the per-unit cost is low. Calcium chloride desiccants cannot be recharged.
How long does a desiccant packet last?
Under normal conditions, silica gel packets are effective for 4 to 12 months. The actual duration depends on how humid the environment is and how well the package is sealed. A tightly sealed poly bag extends effectiveness significantly compared to a loosely closed corrugated box.
What is the difference between silica gel and calcium chloride?
Silica gel adsorbs moisture onto its surface, stays solid, and can be recharged. It works well under standard atmospheric conditions. Calcium chloride absorbs much more moisture but liquefies in the process, is single-use only, and is suited to very high humidity environments where silica gel is not sufficient.
Do I need desiccants if I am already using VCI packaging?
For many metal applications, VCI alone provides sufficient protection. For high-value parts, long transits, or ocean freight where humidity can be extreme, adding desiccants alongside VCI packaging gives the most complete protection by controlling both moisture levels and corrosion chemistry.
Can Benchmark help me find the right desiccant for my application?
Yes. Our team works with operations across Ohio and the Midwest to match the right moisture protection products to each shipping and storage application. Contact us for product recommendations.
KEEP LEARNING
Explore more protective packaging and shipping guides from Benchmark Industrial.VCI Corrosion Protection Guide
How VCI paper, poly bags, and sprays protect metal parts from rust during shipping and storage.
Protective Packaging Guide
Bubble wrap, foam, air pillows, and more: how to protect products inside the box.
Pallet Containment Solutions
Pallet covers, stretch film, and strapping for securing loads during transit.
Corrugated Guide
Flute types, ECT ratings, and how to choose the right corrugated box for your product.
Shop Benchmark's full selection of desiccants and protective packaging,
or contact us for product recommendations and volume pricing.