A police officer has described to a court the "excruciating pain" and temporary loss of vision he experienced when acid was allegedly thrown on him and three fellow officers during a siege of a Port Sorell home in 2021.

The officer was a member of the Tasmania Police Special Operations Group (SOG) tasked with attempting to breach the front door of Daniel Victor Gandini's home in July that year for alleged family violence.

Mr Gandini, who refers to himself as Diplomat Dan or simply Dan, is on trial in the Supreme Court in Burnie accused of assaulting his ex-wife and splashing acid on four police officers.

The accused is representing himself in the trial and during opening statements and cross-examination of witnesses he has claimed that he was a victim of domestic violence, and that he was "in the peaceful occupation" of his home on July 8, 2021, when police surrounded it in what he described as a "siege".

The court has heard he locked himself in his house and refused to negotiate with police or come out for 11 hours until officers breached his door with an explosive at 9:45pm that night.

He has claimed his ex-wife orchestrated a bomb hoax, which was why there was such a significant police response to her claims of assault, but she told the jury he had previously said he would blow up the house if police ever attempted to arrest him.

Accused wore 'goggles' and threw 'a liquid at us', officer tells court

Giving evidence in the trial on Wednesday, a SOG officer said his team had received intelligence that Dan previously had experience working with explosives in the mining industry.

He told the jury that he was at the front of the group of SOG officers holding a ballistics shield when the door was breached.

He explained to the jury that the liquid had a yellow tinge and he initially thought it was fuel.

He said the liquid went all over the shield and his helmet, clothing and face covering.

"As it went on to my face, I could immediately feel burning and the vision in my right eye was severely impacted," he told the jury.

He said the SOG officers had concerns about possibly being covered in a flammable liquid, and that he retreated and washed himself off with a neighbour's garden hose.

The jury was told Dan then exited the house and began verbally abusing officers and advancing on them "aggressively" before being shot with beanbag rounds fired from a shotgun, and then arrested.

Another officer referred to the bean bags as "less lethal munitions", and the jury was shown photos of the subsequent bruising to Dan's body.

Officer says clothing began to melt

The SOG officer said he noticed after the arrest that his clothing had begun to melt and disintegrate where the liquid had been splashed on it and told paramedics that some had gone in his eye.

"[I felt] excruciating pain … and there was some burning sensation on my forehead and nose," he said.

He said he was taken to the Mersey Community Hospital for further treatment.

The accused has claimed the trial is a "vexatious and malicious" prosecution and that on that day police were attempting to cause him "grievous bodily harm" and "murder" him.

In cross examination of several police officers so far, the accused has suggested they were acting on false information, and in one instance described his ex-wife's demeanour as "hysterical".

She previously told the jury she had endured "years of abuse" when she fled the house with their children that morning before calling police.

The trial before Chief Justice Alan Blow will hear from all police officers in attendance on the day and is expected to conclude next week.