They have tried surgical masks and diving goggles, even wrapped their arms and faces in clingfilm to shield themselves from the teargas and pepper spray the police are firing at them, but the most indispensable piece of kit for almost every Occupy Central protester is the umbrella.Whether spray-painted with slogans out on the street, or adapted as multicoloured virtual logos on social media, umbrellas have become the most visible symbol of the demonstrators’ campaign for a more democratic Hong Kong. For its supporters and, increasingly, the media, the growing movement is now “the Umbrella Revolution”.Portable umbrellas, often turned inside out to provide better protection, were the main line of defence on Sunday night for the huge crowds of protesters trying to push past barricades thrown up in the central financial district. In between firing bursts of pepper spray from backpack sprayers, riot police seized and destroyed as many as they could.So valuable are they to the protesters – not only against pepper spray but the blazing midday sun – that by Monday morning, Associated Press was reporting that supporters had donated hundreds of replacements, which were being handed out to demonstrators who needed them at special distribution stations on the fringes of the protest zone.Pleasingly perhaps, in view of the use to which they are being put, the vast majority of the world’s umbrellas – historically a symbol of shelter and protection – have long been made in China, which has called the protests illegal and backed the police crackdown. The city of Shangyu alone boasts more than a thousand umbrella factories.Hong Kong’s demonstrators may take heart from the fact that the accessory has already lent its name to one successful revolution: in November 2007, a huge gathering of umbrella-toting protesters in the Latvian capital, Riga, triggered the downfall of the country’s unpopular prime minister, Aigars Kalvītis, and his government. That Umbrella Revolution, though, was so named because for almost the whole month during which it took place, it didn’t stop raining.