Two men accused of involvement in a plot to bomb London's transport network said they were buying chemicals for decorating work, a jury has heard.
CCTV footage of two of the defendants was shown to the court
Hair product suppliers told Woolwich Crown Court that Manfo Asiedu and Adel Yahya wanted large quantities of liquid hydrogen peroxide.
Prosecutors say 443 litres were bought from three shops ahead of 21 July 2005.
Mr Asiedu, 33, Mr Yahya, 24, and four other men deny conspiracy to murder and conspiracy to cause explosions.
Muktar Said Ibrahim, 28, from Stoke Newington, north London
Ramzi Mohammed, 25, from North Kensington, west London
Yassin Omar, 26, from New Southgate, north London
Hussein Osman, 28, of no fixed address
Manfo Kwaku Asiedu, 33, of no fixed address
Adel Yahya, 24, of High Road, Tottenham, north London
The other men on trial are: Muktar Ibrahim, Hussein Osman, Yassin Omar and Ramzi Mohammed.
The jury heard that one order for hydrogen peroxide from Pak Cosmetics in Finsbury Park, north London, was so large that the manufacturing company had to make a new batch.
Mr Yahya is accused of helping to plan the alleged attacks while the others are all said to have set out on 21 July 2005 to carry out suicide bombings as part of an "extremist Muslim plot".
Muhammed Atif, a sales assistant at Pak Cosmetics, described to the court how Mr Yahya - using the name Yousef - came in to buy the substance.
"He mentioned they wanted to buy it in larger quantities," Mr Atif said.
Mr Asiedu is one of six men who deny conspiracy to murder
"At a later stage, he said they were carpenters and they used it for washing some wood and stuff. He said they used it in building work."
CCTV footage of Mr Asiedu and Mr Ibrahim buying more than 200 litres of hydrogen peroxide at Pak Cosmetics two days before the 7 July terror attacks was also shown to the court.
It also showed both men using upright trolleys to wheel the boxes of the product out of the store.
Christopher Diaper, director of the Hairways in Tottenham, north London said Mr Asiedu bought the shop's entire stock of the high-strength peroxide on 19 May 2005.
"When I asked what the product was going to be used for, I was told it would be for the stripping of wallpaper, that they were doing some flats up and that this was a quick and efficient way of doing it," he told the court.
"When I suggested that this was a dangerous product to use, I was told it was no problem, that they had done it many times before and this was the best product for doing the job."
Mr Diaper said he decided to question Mr Asiedu because it was unusual for someone to buy so much liquid hydrogen peroxide, generally used to bleach hair.
But he said he was not aware it could be used to make explosives.
The bombs were allegedly made at Mr Omar's flat in New Southgate, north London, using a mix of the liquid hydrogen peroxide, chapatti flour, acetone and acid.
On Thursday, the manager of a different hair products supplier told the court that Mr Asiedu had told her he was buying peroxide for "stripping paint".
The trial was adjourned until Monday.