For Adelaide Hills winemaker James Erskine, tasting a pet-nat for the first time was a revelation. "I was in London in late 2010," says Erskine. "Doug Wregg from Les Caves de Pyrene [the natural wine specialist importers] sat me down and said, 'I'm going to show you some things you've never tasted before'."
One of those things was a beautiful, slightly cloudy, sparkling wine from the Loire Valley. Wregg told the young Australian it was a pet-nat, or pétillant-naturel, a naturally sparkling wine that had finished fermenting in bottle and had not had anything added to it - no acid, no yeast and no preservatives: the carbon dioxide trapped inside the bottle was keeping the wine fresh.
"I had only just started making wine," says Erskine. "And I knew I wanted to move towards not using any sulphur dioxide, but wasn't sure how. Here was a wine that answered that question."
The next year, under his new label Jauma, Erskine produced what he reckons was the first Australian wine to be labelled as a pet-nat: a gently fizzy grenache called Biggles.
"I loved it," he says. "But it was a bit too weird for most people. In fact, the only one who bought any was Nick Hildebrandt at Bentley."
Just six years later and pet-nat has gone from weird novelty to bona-fide trend. You'll find pet-nats being poured by the glass in plenty of bars and restaurants across Australia, and indie bottle-shop fridges are happy hunting grounds for lovers of the style, with new labels emerging all the time.
The Adelaide Hills is ground zero for Australian pet-nats - not surprising, perhaps, given that the style is so closely associated with the natural wine movement, and a lot of people who share the natural sensibility have gathered in the Hills over the last few years. As well as Jauma's excellent wines - Erskine made three pet-nats this year, one from chenin blanc, one from grenache and one a blend of red and white grapes - other pet-nat producers worth tracking down here include Ngeringa, BK Wines, Lucy Margaux, Gentle Folk and The Other Right.
The style isn't limited by regional constraints, though. You'll find good warm-climate pet-nats from Delinquente in the Riverland and Yangarra in McLaren Vale, and cold-climate pet-nats from Cobaw Ridge in the Macedon Ranges and Stefano Lubiana in southern Tasmania. And you'll find pet-nat producers as far afield as Brave New Wine in WA's Great Southern, Sassafras and Ravensworth in the Canberra District, and The Wine Farm in southern Gippsland.
Another early exponent of the pet-nat style in Australia was Gilles Lapalus, a French-born winemaker, formerly at Sutton Grange winery in central Victoria, now making wine under the Bertrand Bespoke label.
In 2011, as James Erskine was putting his still-fermenting grenache into bottle, Lapalus was wondering what to do with the small quantities of shiraz, cabernet, sangiovese and viognier grapes he'd managed to harvest at Sutton Grange during that infamously wet vintage. Inspired, he decided to blend them all together to make a sparkling rosé, bottled before it finished fermenting and released before Christmas that year.
"I called it 'Ancestrale'," says Lapalus. "The rustic, ancestral method. This is how sparkling wines were made before vignerons in Champagne refined the technique of secondary fermentation."
Rusticity is part of pet-nat's appeal. There's something wonderfully old-fashioned and wholesome about drinking what's effectively nothing but fermented (and often still fermenting) grape juice. And because it's hard for winemakers to accurately measure fermentable sugar levels at bottling, or how much yeast lees and other suspended matter will end up in the finished product, some pet-nats can be unpredictably lively and frothy when they're opened.
The better producers have learned how to tame the beast, though, and some - such as The Wine Farm - even go to the trouble of disgorging the lees from their pet-nat before release, resulting in a crystal-clear wine.
This is something James Erskine noticed when he attended Bulles au Centre, a natural wine fair in the Loire Valley earlier this year, where he poured a selection of Australian pet-nats alongside leading French producers of the style such as Vincent Carême and Les Capriades.
"Most of the winemakers there are disgorging their pet-nats," he says. "They're looking for clean and pretty wines. Finished wines. But here, a lot of winemakers are happy to sell their pet-nats early, as they come - cloudy, rustic, unfinished. Maybe it's because, here in South Australia at least, we grew up drinking cloudy Coopers beer: we've got an inbuilt acceptance of rusticity."