When you’re choosing fermentation equipment, one of the most common questions Irish homebrewers ask is whether to go with a glass or plastic demijohn. On the surface, they both do the same job but over time, the differences become much more noticeable.
Here’s a practical, experience-based look at how glass and plastic demijohns compare, and why the choice matters.
Flavour Neutrality: Where Glass Shines
Glass demijohns are completely non-porous. That means they don’t absorb flavours, aromas, or cleaning chemicals. For wine, mead, cider, or delicate beers, this is a big advantage. What goes into the demijohn, and what comes out, is exactly what you intended.
This is why most experienced brewers gravitate toward glass demijohns when planning repeat batches or long-term ferments.
Plastic demijohns, even food-grade ones, can absorb smells over time. If you’ve ever fermented a strong cider or heavily hopped brew in plastic, you may notice those aromas lingering into the next batch.
Cleaning and Hygiene
Cleaning is where the difference really shows after a few brews. Glass demijohns can be scrubbed thoroughly using bottle brushes without worry. You can use proper bottle brushes, soak them in cleaner, and visually inspect the interior to make sure they’re spotless.
Plastic scratches more easily, and those scratches can harbour bacteria. In many cases, once a plastic demijohn is scratched, it’s effectively compromised.
For brewers working in sheds, garages, or utility rooms being able to fully clean and sanitise your demijohn is essential.
Longevity and Long-Term Value
A well-made glass demijohn can last for decades if handled correctly. Plastic, on the other hand, has a limited lifespan and often needs replacing after repeated use.
If you brew regularly, investing in glass demijohns tends to pay off over time, even if the initial cost is slightly higher.
Temperature Changes and Fermentation Control
Ireland’s climate is relatively mild, but indoor brewing temperatures can still fluctuate between seasons. Glass handles temperature changes more predictably during fermentation, while plastic can flex slightly as pressure builds.
Regardless of material, pairing your demijohn with the correct bung and bubbler (airlock) is critical to managing pressure and preventing oxygen exposure.
Using correctly sized accessories also reduces the risk of leaks or blow-offs during active fermentation.
Availability and Delivery in Ireland
Glass demijohns are heavier and more fragile, which means stock levels and delivery matter more than with plastic. When browsing demijohns for sale in Ireland, it’s worth choosing a supplier that lists accurate stock and replaces any breakages that occur in transit. At hooleyhomebrew.ie we replace free of charge any glassware damaged in transit
Final Thoughts
Plastic demijohns can work for short-term or experimental use, but for flavour stability, hygiene, and longevity, glass consistently comes out ahead. That’s why we only stock glass demijohns they’re simply better suited to repeat brewing in real-world conditions.