A dyslexic teenager, placed on probation yesterday for making an explosive substance favoured by Islamist terrorists, said he once took a sample of the powder through the Lo Wu border to test whether the authorities would detect it. The 14-year-old Form Two pupil took triacetone triperoxide, or TATP, across the border because he knew it did not contain nitrogen and wanted to test the sensitivity of the border checkpoint detectors, which check for nitrogen in explosives. The teenager made the disclosure to a psychologist, whose report was handed to the juvenile court at Kowloon City Court at the sentencing hearing yesterday. The teenager earlier pleaded guilty to making an explosive substance. Magistrate Denis Lau Wing-shing said yesterday that if the border authorities in either the mainland or Hong Kong had found the explosive substance, they would have considered it a criminal offence. As part of the probation order, Lau placed the teenager under a daily curfew from 8pm to 6am and ordered him to do as his probation officer instructed, including receiving psychological assistance and attending community services programmes. Although a lawyer pleaded with the magistrate to acquit the teenager or give him a lighter sentence, Lau handed down the probation order, saying it would last longer and be a better deterrent. The teenager's problem was his 'curiosity, or perhaps over-curiosity', the lawyer said. He has promised to be careful in future. Instead of explosives, he has turned his attention to studying machines, guided by his father, a mechanic. He said he learned how to make the explosive online, did it for fun and gave it to two classmates at a secondary school in Kowloon Tong. One of the pupils, 13, was injured when he ignited a tissue fuse attached to two plastic bottles containing TATP. He set off the blast on the night of March 27 at a store in Wan Hon Street, Kwun Tong. When the teenager was arrested, police found 19 grams of TATP in his San Po Kong home. He told police he had made the explosive powder three times in the presence of his classmates. He had bought the chemicals from local hardware stores and pharmacies. Police found articles on TATP on his computer. The defence lawyer told the court that the teenager, who is dyslexic, had improved academically in recent months. Meanwhile, a senior customs officer said detection was usually focused more on imports rather than exports. 'It is impossible to inspect every one of the 200,000 travellers who cross the Lo Wu border every day,' he said, adding that sniffer dogs and X-ray machines were used as deterrents. A customs spokesman said anyone caught importing or exporting explosives, arms or ammunition without a licence would be charged.