Soft vs Hard Spiles: Which Works Best for Cask Ale

Last updated: 29 June 2026

Most pub licensees grab whichever spile is lying on the cellar shelf and don’t give it another thought. That’s exactly why so many pubs end up with flat ale, over-carbonated ales that spray when tapped, or casks that drop quality halfway through the week. The choice between soft and hard spiles isn’t academic—it directly affects how your beer tastes, how long it lasts in the cellar, and whether your customers will drink it or send it back. I’ve seen pubs lose GP points because they didn’t understand this one detail, and I’ve also seen cellars transformed by getting it right.

If you’re running cask ale in your pub, you need to know the difference. Not because you’re training to be a cask sommelier, but because the wrong spile choice costs you money in waste, customer complaints, and stock variance that you can’t explain. This guide walks you through what soft and hard spiles actually do, when to use each one, and how to spot the mistakes that lose you pint after pint.

What Is a Spile and Why It Matters

A spile is a wooden peg driven into the shive hole (the hole at the top of a cask) to manage gas escape and preserve the ale’s condition. It’s not decorative, and it’s not optional. Every cask of ale should have a spile in place from the moment it arrives until it’s fully served.

The reason spiles exist is simple: cask ale is a living product. It continues to condition in the cellar. CO2 is being produced by residual yeast. Pressure builds. If you don’t manage that pressure, the ale either becomes flat (if gas escapes uncontrolled) or develops excessive carbonation (if gas is trapped). Either way, the customer gets a poor pint.

The spile is your only tool for controlling how much gas escapes and how fast. Get it wrong, and you’re losing margin on waste, customer returns, and stock variance. Most pubs that move to disciplined cellar management—proper temperature control, weekly line checks, and correct spile selection—find that their stock GP improves noticeably within a couple of months.

Soft Spiles: When and How to Use Them

A soft spile is a porous wooden peg, usually made from a softwood like pine. You can actually see the grain and it’s light enough to compress slightly between your fingers. The porosity is the key: gas can escape through the wood as pressure builds, but it does so slowly and in a controlled way. This is what you want for most casks when they first arrive.

When to Use a Soft Spile

Use a soft spile when:

• A new cask arrives and is being settled into the cellar (the first 24–48 hours).
• The ale needs to condition and drop in carbonation before it’s ready to serve.
• You’re serving from a cask that’s still in condition and needs gradual CO2 release.
• You’re managing an ale that arrived slightly under-carbonated and needs time to develop body.

The soft spile does one job: it allows the ale to breathe while you’re still pulling pints. Think of it as a pressure relief valve. As people drink from the cask, the pressure inside drops. The soft spile lets air back in (or allows CO2 to escape as the yeast continues to work) without exposing the ale to oxidation or allowing it to go completely flat.

The Practical Reality of Soft Spiles

Here’s something only someone who’s actually managed a cellar will tell you: soft spiles don’t last forever. After a week or so in a cask, they start to break down. The wood softens, it becomes less effective at controlling gas escape, and pieces of it can actually come loose and end up in the ale. I’ve personally pulled spile fragments out of a line more times than I’d like to admit. Replace your soft spiles regularly—don’t wait until they’re falling apart.

Also, a soft spile only works if the cask is at the right temperature. Cold cellars (below 12°C) slow yeast activity and gas production, so the soft spile has less work to do. Warm cellars (above 16°C) speed it up dramatically. If your cellar is running hot, a soft spile won’t let gas escape fast enough and you’ll get over-carbonation within days. Cellar temperature is not negotiable if you’re storing cask ale properly, and spile choice depends partly on how consistent your temperature control is.

Hard Spiles: Purpose and Application

A hard spile is a solid wooden peg, usually made from a denser wood like beech or oak. It doesn’t compress. It doesn’t let gas through. It’s a complete seal.

A hard spile works by completely blocking gas escape from the cask, creating an airtight seal that preserves the ale’s condition during storage or transport. Once a hard spile is in place, nothing gets in or out until you remove it.

When to Use a Hard Spile

Use a hard spile when:

• You’re storing a cask for future service and want to lock in its current condition (moving it from one pub to another, or holding stock for a future event).
• An ale arrives badly over-carbonated and you need to halt all gas escape while it settles (rare, but it happens with brewery delivery errors).
• You’re finished serving from a cask and want to preserve any remaining ale for a day or two (though this is generally not best practice).

The hard spile is not what you use for active service. If you put a hard spile in a cask you’re pulling pints from, you’ll trap pressure inside. Within 24–48 hours, when you try to pour, the ale will spray out violently. Your customer gets a glass half foam, half liquid. You get a complaint. This is one of the most common errors I see in pubs that don’t have someone managing the cellar properly.

The Removal Problem

Here’s the practical issue with hard spiles: when you switch from storage to service, you have to remove the hard spile and replace it with a soft spile. Many pubs forget this step, or they remove the hard spile and leave the hole open (which exposes the ale to oxidation immediately). The ale then goes off within 48–72 hours. You’ve got a dead cask, a waste entry you have to explain, and GP down the drain.

Always keep a soft spile ready when you’re about to put a cask on service. Switch them immediately. Don’t leave a cask open-shived for more than a few minutes.

How to Choose the Right Spile

The decision between soft and hard isn’t mystical. It comes down to three questions:

1. Is the ale currently being served from?

If yes: soft spile, every time. The ale is losing volume as people drink, and it needs to be able to release pressure gradually.

2. Is the ale being stored for future use?

If yes: hard spile. You want to lock in the condition and keep it stable until you’re ready to serve.

3. What is your cellar temperature doing?

This is the one most pubs don’t think about. If your cellar is running cold (11–12°C), a soft spile will work well because gas production is slow. If it’s warm (15–16°C), gas production is faster and a soft spile might not vent enough. You might need to check more frequently or even look at your temperature control first before you blame the spile.

The single most important thing to know about spiles is that the choice depends on what stage the cask is at, not on the type of ale. You don’t need different spiles for different beers. You need the right spile for the right stage of that cask’s life.

If you’re trying to track this across multiple casks and multiple stages, it becomes complicated fast. That’s when a system like StockTap pub stock app actually saves you time, because you can log which spile is in which cask and when you made the switch. But more on that later.

Common Mistakes That Waste Beer

After 15 years running a cellar, I’ve seen the same errors repeat:

Mistake 1: Leaving a Soft Spile in Too Long

The ale is ready to serve, but the soft spile stays in because nobody checked. After three or four days, the ale has lost carbonation and tastes thin. You switch to a hard spile thinking it will recover the condition. It won’t. The damage is done. The ale is now flat, and you either have to sell it at a discount or waste it.

Mistake 2: Switching to a Hard Spile During Service

Someone thinks they’re helping by “locking in” the condition. They put a hard spile in a cask that’s actively being served. Pressure builds. Next person to pour it gets a spray of ale and foam. Customers complain. The ale goes off because it’s been abused. Waste, complaint, GP gone.

Mistake 3: Leaving a Cask Open-Shived

A cask finishes service. The soft spile comes out. Someone forgets to put either a hard spile or a new soft spile in, and the shive hole is just open. The ale is now exposed to oxygen. It oxidises within hours. If it’s a premium ale, that’s a significant loss. If you’ve got multiple casks at this stage, it compounds.

Mistake 4: Not Checking Spiles During Weekly Line Checks

This is the big one. Most pubs do a weekly line check (if they do it at all) to clean the lines and check the pressure. But they don’t actually look at the spile or ask: is this the right one for this stage? If you’re not logging what spile is in each cask and when you switched it, you’re flying blind. The number that actually matters is wet GP by line, not a single headline stock figure, and spile management directly affects that because it affects how long each cask stays in sellable condition.

At my own pub, I was running stock on a tangle of spreadsheets and still losing track of partial kegs and partial casks. I couldn’t remember which cask had been switched to service mode three days ago and which was still settling. I built a simple count routine where I logged the spile type, the date of the switch, and the condition of the ale during my weekly count. Within a fortnight, my variance went from guesswork to a number I could actually trust. No more surprises on the week’s stock.

Tracking Cellar Decisions for Consistency

Here’s the reality: most pubs don’t have a system for tracking spile changes. Someone changes a spile, doesn’t tell anyone, and two days later someone else doesn’t know which stage the cask is at. Over time, you lose consistency. One week the ale tastes great. The next week it tastes flat. Your regulars notice. They go somewhere else.

The simplest way to fix this is to log three things every time you touch a cask’s spile:

• Which cask (brewery and cask number or your own identification).
• What spile type went in (soft or hard).
• What date and why (e.g., “switched to soft 25 June—ready for service”, or “hard spile 23 June—storage”).

If you’re already doing weekly SmartPubTools line checks with a structured routine, you can add spile notes to the same record. If you’re not doing weekly checks yet, the spile management becomes your entry point. Start with the cellar. Prove to yourself that you can make a small change and see it in your numbers. Then expand from there.

A 1% stock loss on wet sales quietly costs a typical pub £3,000–£5,000 a year. Most of that loss isn’t theft. It’s measurement error, forgotten wastage, and poor cellar management. Spiles are one part of that picture, but they’re a part that most pubs never optimise. If you’re losing 1% and you tighten your spile discipline, you could recover 0.3–0.5% just from that one change. That’s £900–£2,500 back in your pocket.

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