Plastic Shives for Breweries: A Guide to Two-Piece Cask Shives, Sizing and UK Manufacturing
The shive is one of the most important sealing components in a cask of beer. It provides the access point for venting, tapping and resealing, and it has to perform consistently across every cask it is fitted into. Get the shive right, and the rest of the cask process runs smoothly. Get it wrong, and the result is leakers, contamination and wasted product.
At UB Plastics, we have been manufacturing plastic shives for the British brewing industry since 1983. From our site in Burton-upon-Trent, we produce two-piece shives for breweries across the UK, Ireland and mainland Europe, supplying independent and craft brewers alongside some of the largest names in beer.
This guide explains what a plastic shive is, how our two-piece design works, the two sizes we manufacture, and what to look for when sourcing brewery shives from a UK plastic manufacturer.
What Is a Plastic Shive?
A plastic shive is a precision-moulded sealing component fitted into the bushel at the top of a cask. It seals the cask during filling, transport and storage, and provides the central aperture through which the cask is vented and broached when it is tapped for service.
In practical terms, a shive needs to do three things well: seal reliably against the cask bushel, withstand the impact of broaching, and maintain a clean, hygienic seal throughout the cask’s journey from filling to dispense. During broaching, a hard plastic or wooden peg is driven through the centre of the shive to open the cask, with a tut then used to reseal the hole. Shives are single-use components. Once a cask has been served and returned, the shive is removed and disposed of, with a fresh shive fitted for the next fill. Because shives are in direct contact with beer, the materials, dimensions and consistency of manufacture all matter significantly.
UB Plastics manufactures plastic shives specifically for stainless steel casks used across the UK brewing industry. Our shives are produced from virgin food-grade materials, moulded at our Burton-upon-Trent facility using high-volume tooling and process controls that maintain batch-to-batch consistency.
We manufacture two-piece shives only. We do not produce ribbed shives or shives intended for plastic casks. If your operation uses stainless steel casks and needs a reliable, well-engineered two-piece shive, our range is built for exactly that application. We supply independent and craft brewers with the same quality and service we provide to the largest names in the industry.
The UB Plastics Two-Piece Shive Design
A two-piece shive consists of a durable LLDPE body combined with a flexible EVA sealing band fitted around the body. The body provides the structural form that locks into the cask bushel and houses the central aperture for venting and tapping. The sealing band, which sits in a groove around the body, deforms slightly when the shive is fitted, creating a tight seal against the inside of the bushel.
This two-piece construction matters because it separates the two jobs the shive has to perform. The rigid body provides dimensional stability and resistance to broaching forces, while the softer sealing band deals with the variability that exists in real-world cask bushels. Bushels wear over time, and a shive that relies solely on a rigid body to seal will start to leak as soon as the bushel moves out of fresh tolerance. A flexible band absorbs that variation and keeps the seal intact.
For breweries managing fleets of casks at different stages of their working lives, this matters commercially. A shive that continues to seal on a slightly worn bushel keeps that cask in service rather than pulling it out for repair or replacement.
The Two Sizes We Manufacture: No. 4.5 and No. 5
UB Plastics manufactures shives in two standard sizes: No. 4.5 and No. 5. The body dimensions are the same across both sizes. What differs is the size of the sealing membrane.
No. 4.5 Shive
The No. 4.5 has the larger sealing membrane of the two. The larger membrane gives more deformation when fitted, which makes the No. 4.5 particularly effective on cask bushels that have started to show wear or damage. If your cask fleet contains bushels that have been in service for some time and you are seeing intermittent leakers, the No. 4.5 is often the practical fix that keeps those casks productive.
No. 5 Shive
The No. 5 has a slightly smaller sealing membrane. It is the standard option for casks with bushels in good condition, providing a reliable seal without the additional compression of the larger membrane.
Having both sizes available, in matching body dimensions, allows breweries to standardise their fitting process while selecting the correct membrane size for each cask. Many of our customers stock both, using the No. 5 as their default and the No. 4.5 when they need to compensate for bushel wear.
Both sizes are available in a range of colours and can be custom-printed for batch identification or brand differentiation, which is useful for breweries running multiple products or working with cask returns from the trade.
Manufacturing Quality: What to Look for in a Plastic Shive Supplier
Brewery shives are a high-volume consumable, and the quality of the manufacturing process has a direct impact on operational performance. When evaluating suppliers, the following considerations should sit at the top of the list.
Material Selection
The body material needs to be rigid enough to resist broaching forces but tough enough not to crack under impact. The sealing band needs to be flexible enough to deform against the bushel without taking a permanent set. UB Plastics manufactures shive bodies from LLDPE and sealing bands from EVA, both food-grade polymers proven across decades of brewery use.
Dimensional Consistency
Shives that vary in body diameter or band thickness will produce inconsistent sealing across a cask fleet. Our injection moulding process uses precision tooling and tightly controlled parameters, with typical dimensional tolerances of ±0.1mm. In-process quality checks during production ensure that every batch meets specification.
Batch Consistency
Breweries placing repeat orders need confidence that shives received next quarter will perform identically to those received last quarter. UB Plastics manufactures over 100 million parts per year across 23 injection moulding machines, with documented quality controls that maintain consistency across every production run, regardless of order size.
Sector-Specific Experience
UB Plastics has been moulding plastic products for the brewing industry since 1983, and we are based in Burton-on-Trent, the UK’s brewing capital. We have over five decades of experience specific to the brewing and beverage market, and a suite of machinery and technology perfectly suited to manufacturing in this niche. This means we deliver consistently high quality products with a service our clients can count on.
ISO 9001:2015 Certification
UB Plastics operates an ISO 9001:2015-certified quality management system covering every stage of production. For procurement teams that require formal supplier documentation, we can provide material declarations, food contact compliance evidence and the audit-ready paperwork that brewery quality functions need.
The Benefits of Sourcing Brewery Shives from a UK Manufacturer
Direct Manufacturer Relationship
Because UB Plastics manufactures shives at our own UK site rather than distributing components made elsewhere, you are dealing directly with the people producing the parts. Specification questions, tolerance discussions and any quality concerns are handled by the team running the production process, not by an intermediary.
Shorter Lead Times and Stockholding
Local production means shorter transit, faster response on urgent requirements, and the ability to hold stock close to UK customers. For a consumable component used in significant volumes during the brewing calendar, this translates to lower stockholding burden on your side and greater flexibility when demand peaks.
Continuity of Supply
We maintain stockholding capability and high-volume production capacity to support continuity of supply through busy periods. Brewing demand is rarely flat across the year, and a UK manufacturer with the production capacity to respond is a practical advantage when seasonal volumes increase. This applies equally to independent breweries placing modest orders and to large-scale producers running national distribution.
Long-Term Industry Experience
UB Plastics was founded specifically to supply the brewing sector, replacing traditional wooden cask components with modern plastic alternatives. Over five decades, we have built the technical knowledge and the customer base to support breweries of every size, from independent craft operations to global names.
Complete Cask Furniture from a Single UK Manufacturer
Plastic shives are part of a wider range of cask furniture that UB Plastics manufactures for the brewing industry. Sourcing all your cask components from a single UK manufacturer simplifies procurement and ensures consistency across the fitted assembly:
Our plastic pegs are durable HDPE pegs used to reseal casks after broaching, helping maintain freshness and prevent leakage.
Our keystones are robust thermoplastic elastomer closures for secure cask sealing, available in standard and tut designs for easy removal and high-temperature washing.
Our keystone bungs are designed to pair with our keystones, enabling efficient one-piece extraction after tapping.
View the full brewing product range for the complete offering.
Frequently Asked Questions About Plastic Shives
What is a plastic shive used for?
A plastic shive seals the top aperture (the bushel) of a cask. It allows the cask to be vented and broached for service while maintaining a tight seal during filling, transport and storage. Shives are single-use items, fitted at filling and disposed of after the cask is returned for cleaning.
What sizes of plastic shive does UB Plastics manufacture?
UB Plastics manufactures two-piece shives in No. 4.5 and No. 5 sizes. The body dimensions are identical across both sizes; the sealing membrane is larger on the No. 4.5.
Which shive size should I use?
The No. 5 is the standard option for cask bushels in good condition. The No. 4.5, with its larger sealing membrane, is the practical choice for bushels that have started to wear and where smaller shives are starting to leak. Many breweries stock both sizes.
Does UB Plastics make ribbed shives or shives for plastic casks?
No. UB Plastics manufactures two-piece shives for stainless steel casks only. We do not produce ribbed shives or shives designed for plastic cask systems.
What materials are UB Plastics shives made from?
The shive body is moulded from LLDPE and the sealing band from EVA. Both are food-grade polymers approved for beverage contact and proven in brewery use.
Can shives be supplied in different colours or with custom printing?
Yes. UB Plastics shives are available in a selection of colour options for batch identification or brand differentiation, and custom pad printing is available for logos, production codes or other markings.
What are the minimum order quantities for plastic shives?
Standard brewing components like shives typically have minimum order quantities starting from 5,000 to 10,000 units. Contact our team to discuss your volumes and receive a tailored trade quote.
Request a Trade Enquiry from UB Plastics
If you are a brewery, beverage producer or distributor looking for a reliable UK manufacturer of two-piece plastic shives in No. 4.5 and No. 5 sizes, UB Plastics has the production capacity, quality systems and brewing-sector experience to support your operation, from independent and craft brewers through to large-scale commercial producers.
We manufacture to food-grade standards with ISO 9001:2015 quality controls, and our team can advise on sizing, provide samples, discuss colour and print options, and offer competitive pricing across order volumes that suit your scale.
Request a Trade Quote or contact our technical team to discuss your plastic shive requirements today.