A teenager at a young offenders institution threw hot water in the face of a prison officer after accusing him of leaving a light on and disturbing his sleep, a court heard.
James Grant was left with unsightly burns and was off work for three months following the attack at Cookham Wood in Borstal.
Ayaub Mohammad was serving a sentence for assault when he launched the attack on October 6 last year.
He had been heating up the water for noodles during the evening when he blamed Mr Grant for kicking the cell door and leaving the light on the previous night.
Prosecutor Stephen Earnshaw said the victim maintained it could not possibly have been him, only to be told: “You are mugging me off.”
Mr Grant walked away but Mohammad called him back. As he put his face close the hatch in the cell he felt the hot water hit the left side of his face.
“He walked away,” said Mr Earnshaw. “Initially, there was no feeling in his face. He went downstairs and told colleagues what had happened.
“They said his face looked as though it was melting. They put a cold compress on it.
Paramedics arrived and he was given a cooling face mask. He had blurred vision.”
Mr Earnshaw said although there was blistering and slight scarring, it was fortunately a superficial burn.
Mr Grant, who sat in court with his pregnant wife, told in an impact statement how the attack had affected him and his family.
Mohammad, from London, admitted inflicting grievous bodily harm.
He had 15 convictions for 28 offences and was serving 18 months for assault causing actual bodily harm at the time of the attack on Mr Grant.
Justin Rivett, defending, that Mohammad came to the UK from Somalia at the age of two with his family.
While his seven brothers and sisters were all law-abiding, he was described as the black sheep of the family.
He found the environment at Cookham Wood difficult, as being tall he was the target for violence, said Mr Rivett. He had since been transferred to Elmley Prison.
Mr Rivett said of the latest offence: “He felt provoked and that was the trigger. He is quick to lose his temper. He has written a letter of apology to Mr Grant.”
Sentencing him to 16 months youth custody, Judge Philip Statman said: “For an offence of this kind as night follows day, there is no alternative but for the court to impose a custodial sentence.”
He told Mohammad: “It is not a case for dangerousness, but it is getting perilously close. Mr Grant has suffered psychologically and continues to suffer as a result of your actions.
“It is clear you have got a problem with your temper. I invite the authorities to give assistance with anger management.”