Beauty and Personal Care, Healthcare Packaging, Home & Garden Packaging, Retail

NatraLock® Ultra Seal

Appealing. Safe. Functional. Sustainable.

Now there is a sturdy, flexible, more sustainable alternative to traditional blister seal and clamshell applications. WestRock NatraLock® UltraSeal features stellar graphic reproduction while allowing heat and RF sealing on a wide range of thermoform blister materials. Uniformity and consistency from roll to roll and sheet to sheet make NatraLock Ultra Seal ideal for high-speed converting, filling and sealing applications. It’s perfect for promotional messages, graphics and compliance information for trade seal blister packaging. With SBS and CNK offerings, NatraLock UltraSeal is uniquely engineered to be used as a clamshell replacement that maximizes shelf appeal and enhances sustainability. Download product guide PDF Order Samples

Features and Benefits

What you can expect from us:

Laminated Structure

The rigidity of paperboard and the tear-resistance of lamination combines for unsurpassed assembly performance of trap seal blister packaging

Heat Seal Compatibility

Consistently seals to a wide variety of thermoformed blister materials, including APET, RPET, PETG, RPETG, PVC, and PLA.

Low Temperature Seal

Low-temperature sealing yields increased line speed, minimized risk of product damage and reduced ink degradation. With a dwell time 20% less than other hot-seal coatings, you’ll see improved results and lower costs.

Product Uniformity

A smooth surface, outstanding ink holdout and best-in-class consistency combine for optimal printability. Polymer coat-weight uniformity provides improved efficiencies and maximum throughput on high-speed filling equipment.

Converting Efficiency

Direct printing eliminates the need to apply heat-seal coating, improving converting efficiency and reducing inventory costs.


Roll-to-roll and sheet-to-sheet consistency makes NatraLock SBS ideal for high-speed converting, filling and sealing applications.

Recycled Fiber Content

CNK is produced with up to 15% recycled fiber, providing an option for meeting your corporate sustainability goals.


Best used with:

  • Healthcare
  • Beauty and Personal Care
  • Media and Electronics
  • Toys
  • Sporting Goods
  • Automotive
  • Home Improvement
  • Tools

Paperboard Calculator

We understand that you rely on us for more than paperboard. In order to provide the best service possible, WestRock has developed roll, sheet and metric conversion calculators to make your job easier.

View the paperboard calculator

Additional Product Information


  • Made with recycled fiber (CNK version.)
  • All WestRock North American paperboard mills are certified to the SFI®, PEFC™, FSC™ Chain of Custody Standards. 
  • Contact your WestRock sales representative for certified fiber availability for this product.

Environmental & Product Safety

  • Notices under US California Proposition 65 and the EU REACH regulation are not required.
  • Elemental chlorine free (ECF) bleached fiber (SBS version).
  • Meets heavy metal limits of the US Model Toxics in Packaging rules and Article 11 of EU Directive 94/62/EC.

This information is subject to change without notice.


  • Produced at an ISO 9001 certified facility.

A clear choice for better security

To help boost security and remove barriers to purchase, we offer Natralock® tear-resistant packaging. As durable and secure as clamshells, Natralock provides superior product visibility and a safer, easier opening experience to help drive sales and profits.

Download one-pager.


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How can we help you meet your business goals? Contact a member of our team to learn more about our paperboard products and services.

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