When you need to keep products cold or frozen during transport, should you use a wet and dry dry ice pack or stick with traditional gel packs? Dry ice remains at about –78.5 °C (–109.3 °F) and leaves no moisture, while water based gel packs maintain 0 °C to 8 °C and gradually melt. This article helps you decide which pack to choose and explains how combining both refrigerants can extend cooling time. You’ll learn the science of sublimation, step by step packing instructions, updated 2025 regulations and innovative trends shaping cold chain logistics. By the end, you’ll know how to safely use wet and dry dry ice packs to protect your temperature sensitive goods.
Difference between wet and dry dry ice packs: We explain how dry ice pack sheets encapsulate solid CO₂ and why they maintain ultra low temperatures without moisture, while gel packs keep goods cool without freezing.
When to combine dry ice and gel packs: Learn the advantages of hybrid cooling systems and how mixing wet and dry ice slows sublimation and stabilises temperatures.
Safe packing guidelines: Step by step instructions for layering dry ice and gel packs, insulating shipments and venting CO₂ gas.
Regulations and safety rules: Understand weight limits, labelling requirements (UN1845) and personal protective equipment needed when handling dry ice.
2025 trends and innovations: Explore automation, sustainability, smart sensors and hybrid systems transforming cold chain logistics.
What Are Wet and Dry Dry Ice Packs?
Direct answer
Wet and dry dry ice pack sheets combine two refrigerant technologies in a single flexible sheet: a water based gel layer (“wet”) and encapsulated dry ice (“dry”). Dry ice pack sheets use sealed polymer cells filled with dry ice pellets; as the dry ice sublimates from solid to gas, it absorbs heat and maintains temperatures near –78.5 °C. Gel packs, on the other hand, freeze water and maintain a moderate 2–8 °C range without freezing the product. By combining these materials, shippers can tailor cooling to either frozen or chilled goods.
Expanded explanation
Dry ice pack sheets are manufactured by placing dry ice pellets or flakes inside a flexible polymer film. Because dry ice sublimates directly to CO₂ gas rather than melting, it leaves no moisture; this prevents water damage to sensitive cargo like electronics, pharmaceuticals or dry goods. The gel layer in a wet dry ice sheet slows down sublimation and distributes cold evenly across the sheet. In contrast, traditional gel packs contain a water based phase change material (PCM) that freezes at around 0 °C; they are perfect for keeping goods cool (2–8 °C) without freezing them. Recent market analyses note that the global dry ice market is projected to grow from USD 1.66 billion in 2025 to USD 2.73 billion by 2032, reflecting increased demand for moisture free cold chain solutions.
How wet and dry pack sheets work
A wet and dry dry ice pack sheet typically has three layers:
| Component | Description | Significance | Practical benefit |
| Gel sheet layer | Flexible material surrounding dry ice pellets | Slows sublimation and distributes cold evenly | Extends cooling effect and reduces hot spots |
| Dry ice core | Encapsulated solid CO₂ that sublimates at –78.5 °C | Maintains ultra low temperatures | Keeps vaccines, biologics and frozen foods below freezing |
| Protective outer shell | Durable polymer film | Prevents leaks and protects contents | Safe handling and reusable until the textile surface becomes unhygienic |
Because the gel layer moderates sublimation, gel sheet dry ice packs can maintain frozen conditions for 24–72 hours depending on thickness and insulation. A practical example is mRNA vaccines requiring –70 °C storage: mini dry ice pack sheets kept them at –78.5 °C for more than 48 hours during international flights.
Practical tips and user advice
When using wet and dry dry ice pack sheets:
Pre chill the packaging: Pre cool containers before adding the sheet to maximise hold time.
Use high quality insulation: Combine dry ice sheets with insulated boxes or vacuum insulated panels (VIP) to reduce heat transfer.
Monitor temperatures: Smart sensors or data loggers can track internal temperatures and alert you to deviations.
Combine with gel packs if needed: When shipping both frozen and refrigerated items, adding gel packs buffers temperature gradients and slows dry ice sublimation.
Table: Cooling methods compared
| Cooling method | Temperature range | Duration (approx.) | Moisture | Best use |
| Mini dry ice pack sheet | –78.5 °C to –18 °C | 24–48 h | None (sublimates) | Ultra low temperatures for vaccines and biologics |
| Traditional ice pack (water based) | 0 °C | 12–24 h | Leaves water | Suitable for chilled produce and drinks |
| Gel pack | 2–8 °C | Varies, typically 24 h | Minimal moisture when melted | Protects goods above freezing, ideal for pharmaceuticals that must not freeze |
User friendly analogies
Think of a wet and dry dry ice pack sheet like a “cold sandwich.” The dry ice core acts as the frozen filling that keeps everything cold, while the gel layers are the bread that insulate and spread the cold evenly. Without the bread, the frozen filling would sublimate quickly and create pockets of cold. Similarly, combining both layers ensures consistent temperatures and longer hold times.
Why Combine Wet and Dry Ice Packs?
Direct answer
Mixing dry ice with gel packs or wet ice can extend cooling time and provide both ultra cold and refrigerated zones within one shipment. Gel packs slow down the sublimation of dry ice, while dry ice stabilises the temperature of the gel packs. This hybrid approach extends the total cooling duration by roughly 12–15 % and balances extreme cold with moderate temperatures.
Expanded explanation
Dry ice sublimates rapidly because of its extremely low temperature. By adding gel packs or regular ice, the water based ice absorbs some of the heat that would otherwise accelerate sublimation. Studies in 2025 show that combining dry ice with gel packs can extend the hold time for shipments from around 48 hours to 60 hours, using roughly 14 lb of total coolant compared with 10 lb of dry ice alone. The wet ice or gel acts as a thermal buffer: it maintains a near freezing layer above the dry ice, slows sublimation and prevents sudden freezing of delicate products. When shipping both frozen and chilled goods, placing gel packs near items requiring refrigeration (2–8 °C) and positioning dry ice above or around items that must remain frozen preserves both categories.
Benefits of hybrid cooling
| Benefit | Explanation | Evidence |
| Extended cooling duration | Gel packs or wet ice reduce the rate of dry ice sublimation, extending cooling duration by approximately 12–15 %. | Data from cold chain tests show hybrid packouts provide up to 60 hours of cold, compared with 48 hours for dry ice alone. |
| Temperature control | Combining refrigerants allows you to ship both frozen and chilled products in one container, avoiding over freezing delicate goods. | Layering gel packs near goods requiring 0 – 5 °C prevents them from freezing while dry ice maintains frozen goods at –18 °C. |
| Cost efficiency | Gel packs supplement dry ice, reducing the total dry ice weight and lowering shipping costs. | For a 72 hour lane, using gel packs reduces the need for extra dry ice, saving up to 25 % on refrigerant cost. |
| Safety and handling | Gel packs reduce the risk of frostbite for handlers, acting as a buffer between bare hands and dry ice. | Handlers can reposition gel packs easily without contacting the ultra cold dry ice. |
Real world example
A seafood distributor shipping frozen fish and live clams across the country uses hybrid cooling. They place gel packs against the live clams to maintain 0–5 °C and layer dry ice blocks on top to keep the fish below –18 °C. According to Dry Ice Corp, combining gel packs with dry ice stabilises the dry ice, slows sublimation and extends shelf life. This method ensures that live shellfish remain alive while the frozen fish stays solid. For a 24 hour journey in a 15 quart container, about 5–10 lbs of dry ice and one pound of gel packs per cubic foot are recommended.
User advice and best practices
Layer the refrigerants: Place gel packs near goods that should stay above freezing and put dry ice above or around frozen items.
Choose the right ratios: Use equal weight of dry ice and product for 48 hour frozen shipments and 1.5 × product weight for 72 hour shipments. For gel packs, one third of the product weight often provides up to 48 hours of refrigeration.
Seal and insulate properly: Use high quality insulation (EPS, PUR or VIP) and fill voids with dunnage to slow heat transfer.
Vent the container: Ensure the package is ventilated to prevent CO₂ buildup. Never seal dry ice in an airtight container to avoid explosion hazards.
Use moisture barriers: Line packages with poly bags or bubble wrap to prevent condensation from gel packs from affecting products.
Actual case: A camping group used a hybrid setup: they placed a dry ice block at the bottom of their cooler, added 20–30 pounds of wet ice above it, then loaded food and drinks on top. This configuration kept beverages cold for 6–8 hours and melted ice absorbed CO₂, reducing gas buildup. Following this approach, the campers enjoyed fresh drinks without waterlogging, illustrating the effectiveness of wet and dry combinations.
How to Pack Wet and Dry Ice Packs Effectively
Direct answer
To pack a wet and dry dry ice shipment, layer the gel packs near refrigerated goods, position dry ice above or around frozen items, and insulate everything within a vented container. Use moisture barriers, pre chill the box and ensure proper labeling and ventilation. Wear protective gloves and avoid direct contact with dry ice to prevent frostbite.
Step by step packing guide
Identify temperature zones: Decide which items require freezing and which need refrigeration. Place gel packs near products that should stay 0–5 °C and dry ice near items that must remain frozen.
Prepare the container: Pre chill the insulated box and line it with a moisture barrier (poly bag or foil liner) to protect contents from condensation.
Layer gel packs: Place gel packs at the bottom or along the sides where you need moderate temperatures. For 24 hour shipments, use roughly one pound of gel packs per cubic foot.
Add products: Insert the products, ensuring sealed packaging to prevent contamination. For seafood or meat, double bag items and use absorbent materials as recommended by FedEx guidelines.
Position dry ice: Place dry ice blocks or pellets on top of or around the products needing freezing. Use 5–10 lb of dry ice per 24 hours with a 15–25 % buffer; plan 15–30 lb for a 72 hour shipment.
Fill voids and insulate: Use dunnage, foam spacers or newspaper to fill empty spaces and reduce convection. Choose appropriate insulation—EPS for short durations, PUR for extended hold times or VIP panels for 72 hour shipments.
Vent the container: Ensure the lid or container has vent holes so that CO₂ gas can escape. Never use airtight containers—pressure buildup can rupture packages.
Seal and label: Close the outer box securely with tape. Label the package with “Dry Ice” or “Carbon dioxide, solid,” include UN1845 and net weight (kg), and display Class 9 hazard labels. Add addresses for shipper and consignee.
Additional packing tips
Wrap dry ice: Wrap blocks or slabs of dry ice in newspaper or paper bags to slow sublimation and protect packaging.
Keep dry ice off food: Avoid direct contact between dry ice and food to prevent freezing or texture changes.
Use separate compartments: For mixed shipments, consider using dividers or smaller compartments within the box to keep different temperature zones separated.
Document contents: Write the weight of dry ice on the label; shipments over 5.5 lb (2.5 kg) require dangerous goods documentation.
Dispose properly: Allow unused dry ice to sublimate in a well ventilated area. Never pour it into sinks or drains.
Practical scenario: A biotech laboratory shipping gene therapy vectors needs –60 °C for 72 hours. They use a dry ice container with blocks and pellets layered together, pre condition the container, and fill empty spaces with custom slices. This maintained –65 °C to –70 °C for 72 hours, ensuring product integrity.
Safety and Regulatory Considerations
Direct answer
Dry ice is classified as a hazardous material for air transport and requires specific handling, labelling and weight limits. Always wear insulated gloves, goggles and long sleeves when handling dry ice; ensure ventilation and never seal dry ice in airtight containers to prevent CO₂ buildup.
Regulations and compliance
Regulatory bodies such as the U.S. Department of Transportation (DOT) and the International Air Transport Association (IATA) classify dry ice shipments as dangerous goods. Key requirements include:
UN1845 labelling: Packages containing dry ice must display “UN1845” and the proper shipping name “Dry Ice” or “Carbon dioxide, solid”. The airbill must state “Dry Ice, 9, UN1845, number of packages and net weight in kg”.
Weight limits: Passenger flights limit dry ice to 2.5 kg (5.5 lb) per package; cargo flights allow up to 200 kg per package. USPS air shipments are capped at 5 lb.
Venting requirements: Dry ice releases CO₂ gas; packages must be vented to prevent pressure buildup. FedEx instructions emphasise using insulated containers with vented lids and placing dry ice on top of products.
Documentation: Shipments over 2.5 kg require a Shipper’s Declaration for Dangerous Goods (unless the contents are exempt), and carriers like FedEx and UPS have additional rules including Class 9 hazard labels.
Material selection: Avoid brittle plastics; containers should withstand low temperatures and pressure changes. Use sturdy polystyrene or polyethylene boxes with ventilation ports.
Safety best practices
Personal protective equipment: Wear insulated gloves, safety goggles and long sleeves to prevent frostbite.
Proper storage: Store dry ice in a well ventilated area; never in sealed rooms or walk in freezers without ventilation.
CO₂ monitoring: In confined spaces or vehicles, use CO₂ detectors to avoid hypercapnia; high concentrations can cause headaches, dizziness and shortness of breath.
Avoid ingestion: Never place dry ice in food or drinks; ingestion can cause serious harm.
Safe disposal: Allow dry ice to sublimate outdoors or in a fume hood; do not pour down drains or place in trash.
Gel pack safety
Gel packs are non toxic and generally safer to handle but still require care. Avoid puncturing the pack; if the gel escapes, wash skin immediately. Gel packs can be reused if the packaging remains intact, making them more sustainable.
Choosing the Right Pack for Different Industries
Pharmaceutical and biotech
Pharmaceuticals often require ultra cold temperatures. Vaccines and biologics may need storage below –70 °C. Gel sheet dry ice packs with controlled sublimation rates maintain these temperatures while providing cushioning to protect vials. In 2025, predictive analytics and IoT sensors enable real time monitoring of pharmaceutical shipments. The North American pharmaceutical cold chain market is expected to reach USD 1,454 billion by 2029.
Food and meal delivery
Frozen foods, seafood and meal kits require consistent freezing around –18 °C. Dry ice sheets can maintain –20 °C for 24 hours, ensuring meat and seafood remain safe. Gel packs protect perishable produce (0–5 °C) without freezing. As e commerce grows, the North American food cold chain market is projected to reach USD 86.67 billion in 2025. Using wet and dry dry ice pack sheets reduces food waste and improves customer satisfaction.
E commerce and meal kits
Disposable dry ice sheets are lightweight and reduce dimensional weight, cutting shipping costs. They can be cut into smaller cells for flexible sizing and combined with smart sensors that adjust the number of sheets based on predictive analytics. Meal kit companies use gel sheet dry ice packs to keep frozen meals at –20 °C for 24 hours, improving customer experience.
Biotech and laboratory samples
Biotech samples such as genetic material or enzymes require reliable cooling and cushioning. Gel sheet dry ice packs maintain low temperatures while cushioning vials and tubes. Real time tracking devices verify temperature compliance and provide audit trails.
Hydrate packs for everyday use
Hydrate dry ice packs are reusable sheets that absorb water before freezing. They are versatile for everyday cooling—picnics, camping trips or transporting seafood—and can maintain refrigerator temperatures for extended periods. These packs can even help maintain refrigerator temperatures during power outages.
2025 Trends and Innovations
Automation and robotics
Labor shortages are prompting adoption of automated storage and retrieval systems (AS/RS) and robotic handlers. Automation reduces labour costs, minimises errors and maintains consistent temperature control. Studies show around 80 % of warehouses remain non automated, highlighting significant growth potential.
Sustainability as a core value
Environmental regulations and consumer demand drive sustainable practices. The global food cold chain infrastructure accounts for roughly 2 % of CO₂ emissions. Manufacturers are developing eco friendly gel packs, compostable packaging and recyclable dry ice sheets. Programs like Cryopak’s R3 Service reuse and recycle materials, saving clients money and reducing waste.
End to end visibility and real time tracking
IoT enabled sensors provide continuous temperature, location and humidity data, allowing businesses to optimise routes and reduce waste. Real time visibility improves customer satisfaction and ensures regulatory compliance.
Infrastructure modernisation and AI
Aging cold storage facilities require upgrades in insulation, data collection and onsite renewable energy. Artificial intelligence analyses historical and real time data to optimise routing, predict equipment failures and forecast demand.
Growth in pharmaceutical cold chain
Gene and cell therapies require ultra cold storage; about 20 % of new drugs fall into this category. The COVID 19 pandemic accelerated investment in cold chain capacity and highlighted the need for reliable dry ice solutions.
Last mile and fresh food logistics
Consumers expect fresh, high quality produce delivered quickly. The North American food cold chain market will reach USD 86.67 billion in 2025. Innovations in packaging and refrigeration address last mile challenges.
Strategic partnerships and integration
Collaboration among food manufacturers, packaging suppliers and technology providers enhances efficiency and resilience. By 2025, approximately 74 % of logistics data is expected to be standardised, enabling better integration across supply chains.
Green and sustainable materials
Sustainable materials like compostable gel packs and recycled cardboard reduce waste and carbon footprints. Innovations such as NexBlu™ GPS use 20 % less material and incorporate recycled graphite beads.
Smart technology integration
Dry ice and gel sheet packs now include sensors that monitor temperature and send alerts when deviations occur. AI recommends the optimal number of sheets per shipment. These technologies improve efficiency and reduce waste.
FAQs
Q1: How long do wet and dry dry ice pack sheets last?
Dry ice pack sheets typically maintain sub zero temperatures for 24–72 hours depending on their thickness and insulation. Gel packs alone provide moderate temperatures for about 24 hours; combining them can extend cooling up to 60 hours.
Q2: Can I reuse dry ice pack sheets?
Yes. Dry ice sheets can be reused until the textile surface becomes unhygienic. Always rehydrate and freeze the sheet before each use.
Q3: Are dry ice packs safe for air freight?
Yes, as long as they are properly packaged and labelled. Keep shipments below 5.5 lb (2.5 kg) of dry ice to minimise regulatory requirements.
Q4: How do I prevent products from freezing when using dry ice and gel packs?
Place gel packs near items that must remain above freezing and position dry ice away from those products. Layering and insulation provide temperature gradients.
Q5: What is the difference between gel sheet dry ice packs and regular gel packs?
Gel sheet dry ice packs use dry ice to achieve ultra low temperatures, whereas regular gel packs rely on water based PCM and maintain 2–8 °C. Use gel sheets for frozen shipments and gel packs for chilled goods.
Q6: How much dry ice do I need per shipment?
A general rule is one pound of dry ice per pound of product for 48 hour shipments and 1.5 × product weight for 72 hour shipments. Use 5–10 lb of dry ice per 24 hours and add a 15–25 % buffer.
Q7: Can I pack dry ice and gel packs in the same container?
Yes. Follow the layering guidelines—gel packs next to refrigerated goods, dry ice above or around frozen items, and vent the container.
Summary and Recommendations
Wet and dry dry ice pack sheets offer a versatile cooling solution. Dry ice provides ultra low temperatures (–78.5 °C) and leaves no moisture, while gel packs maintain moderate temperatures without freezing. Combining these refrigerants extends cooling duration by roughly 12–15 %, allows dual temperature shipments and reduces costs. To maximise performance, pre chill containers, layer gel packs and dry ice correctly, insulate and vent packages, and comply with regulations. Use high quality insulation, wrap dry ice, avoid direct contact with food, and monitor temperature with sensors. In 2025, innovations like automation, sustainable materials and smart tracking are reshaping the cold chain. By selecting the right pack and following best practices, you can protect your products and improve customer satisfaction.
Actionable advice
Assess your shipment: Determine the temperature requirements and transit duration for each product.
Select the right refrigerant: Use dry ice pack sheets for frozen or ultra cold shipments; choose gel packs for chilled goods or pair them for hybrid cooling.
Follow packing protocols: Layer gel packs near products needing refrigeration, dry ice near frozen goods, and insulate and vent the container.
Monitor and document: Use smart sensors or data loggers, record dry ice weight, and label packages with UN1845 and net mass.
Embrace sustainability: Opt for reusable gel packs or recyclable dry ice sheets, and explore circular CO₂ sources to reduce environmental impact.
About Tempk
Tempk is a leading provider of high performance temperature control solutions. Our products include mini dry ice pack sheets, gel sheet packs, hydration packs and insulated packaging. We operate an R&D centre and quality control laboratory to ensure every product meets rigorous standards. Our innovations—such as EcoGel™ gel packs and recyclable EcoPak™ packaging—support sustainability while delivering exceptional performance. Whether shipping vaccines, seafood or meal kits, we provide custom solutions to keep your goods safe.
Call to action: Ready to optimise your cold chain logistics? Contact Tempk’s experts for personalised guidance on choosing wet and dry dry ice pack sheets and stay ahead of 2025 cold chain trends.
