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July 21st 2005 London bomb attack trial - hydrogen peroxide, chapati flour, TATP detonators

No doubt more speculation and some more actual details will emerge from the trial of the six men who are in court over the failed July 21st 2005 bomb attacks on the London Tube and Bus system.

Panic during the ensuing manhunt, led to the shooting to death of the innocent Brazilian Jean Charles de Menezes by the Metropolitan Police.

The Times reports a few details of the home made bombs:

The Times January 16, 2007

How high street ingredients 'could become weapons for mass murder'
Sean O'Neill

The ingredients of the July 21 bombs were acquired in the high street and required little more than a rudimentary knowledge of chemistry to make up. The shopping list of the alleged bombers included hydrogen peroxide — widely used in hairdressing — chapati flour, nail polish remover (acetone), sulphuric acid, batteries, torch bulbs, electrical wires, cardboard and half a dozen food storage tubs, Woolwich Crown Court was told yesterday.

The components were taken to the flat of Yasin Omar for assembly into improvised explosive devices.

That one-bedroom council flat, on the ninth floor of Curtis House, a tower block in New Southgate, North London, was described at the court as the alleged terror cell’s “bomb factory”.

There, three members of the gang are said to have spent long hours sweating over the electric cooker in the small kitchen, boiling huge panfuls of liquid hydrogen peroxide to reduce the chemical into a stronger concentration.

Mr Omar, who has studied for a GNVQ in elementary science at Enfield College, Muktar Said-Ibrahim and Manfo Kwaku Asiedo were said to have worked in shifts from 5am until 11pm each day.

Two large saucepans and a frying pan that were recovered from the building revealed, after scientific examination, clear traces of concentrated hydrogen peroxide.

The liquid peroxide was the most important ingredient. Increasingly it is used in the hairdressing trade as a cream but the gang was said to have identified outlets in Finchley, Tottenham and Finsbury Park where they could buy it as liquid in an 18 per cent concentration. Between the end of April and July 5, 2005, they are alleged to have bought 443 litres in either one-litre or four-litre containers.

Therefore this was not an improvised "copycat attack" following the July 7th bombs.

The peroxide was to form the bulk of what Nigel Sweeney, QC, for the prosecution, described as the main charge of the bombs.

Mr Sweeney said: “The explosive was intended to consist of liquid hydrogen peroxide, concentrated, mixed with chapati flour, the flour being the fuel that would burn and the hydrogen peroxide providing oxygen, so that when fired by a detonator the mixture would explode.”

This concoction was placed inside a series of 6.25-litre plastic kitchen storage tubs that were sealed with a lid. A hole was cut in the bottom of the container, into which a detonator was inserted.

443 litres of 18% hydrogen peroxide solution.

5 x 6.25 litre plastic tubs

Could they have made rather more than 5 bombs with this amount of hydrogen peroxide ?

The detonator was made from a small carboard tube packed with the homemade explosive triacetone triperoxide, better known as TATP.

This was, in turn, to be set off with a small torch bulb attached to one end of the TATP tube and linked by wires to a 9-volt battery, the court was told.


If they could make TATP for the detonators, why not for the whole bomb like the July 7th bombers ?

There seems to be reports of anything like the industrial refrigerator unit which the July 7th bombers installed in their Leeds bomb factory.

How they did not set themselves on fire just using a saucepan or frying pan and an electric cooker, to concentrate the hydrogen peroxide solution, is a mystery.

Extensive tests were carried out by the Forensic Explosives Laboratory using the bomb recipe that was allegedly deployed on July 21 and a variety of detonators. In all cases the devices proved to be “functional”.


Is the Forensic Explosives Laboratory still at Fort Halstead near Sevenoaks in Kent , part of the Defence Science and Technology Laboratory, i.e. the bit of the UK Government's military research and development that was not privatised as Qinetiq ? Conceivably the new Counter Terrorism Centre at Porton Down (.pdf) in Wiltshire, also under the DSTL, might also have been involved in analysing or trying to replicate the bombs.

On July 21, it was alleged, something had gone wrong with the mixture of the main charge in all four bombs that the gang tried to detonate. Another bomb was abandoned.

With one of the accused having left the country 6 weeks before the attack, and another having ditched his bomb on the day of the attack, the possibility of deliberate sabotage of the main explosive charge chapati flour (any finely divided fuel might have done instead) and concentrated hydrogen peroxide oxidising agent should not be ruled out.

There has been a quite a bit of reporting and speculation as to what extent the July 7th bombers had been under police or MI5 surveillance, but there has been much less about any actual surveillance of this gang of East African refugees and immigrants.


See Postman Patel re refrigerators etc., Monday 15th 2006.

A search of Postman Patel site using the names of the accused will provide links, information to the defendents, their bank records, previous convictions, etc., etc., trade in Qat.

Look fwd to reply from the JIC about the MI5 e-mail fuck up. Not that anyone expects any sensible answers.

  1. "If they could make TATP for the detonators, why not for the whole bomb like the July 7th bombers ?"

    Extremely good point. (They may something about refrigeration units but that is only part of the answer).

  2. "How they did not set themselves on fire just using a saucepan or frying pan and an electric cooker, to concentrate the hydrogen peroxide solution, is a mystery."
    It would be interesting to do a 'Hazop' on their process.
  3. "any finely divi[e]ded fuel might have done instead"
    You need to distinguish between: explosion; conflagration etc ... There is a difference and it will help with your analysis (as would a hazop).

TATP sublimates at room temperature so it must be kept cool all the time or it simply disappears. It's manufacture has to be done below 10'C. It is highly friction and shock sensitive and cannot be stored in metalic containers or containers with screw tops.
It is utterly unsuitable for the alleged purpose. Far better to compound and use
a fulminate or one of the tetradecanes or diamines. As for using chapati flour as a substrate the less said the better, even cowshit is better than chapati flour and would yield a better deflagration, it's all really quite laughable and just shows that people will believe anything they are told by the powers that be.

Any knowledgeable schoolboy could formulate an IED of far greater efficiency far more easily and safely with less risk to themselves than this fiasco alledges.

You cannot concentrate hydrogen peroxide by boiling it - it decomposes at an accelerated rate with increasing temperature. Addition of organic material to the sort of hydrogen peroxide you can buy causes it to decompose - flour and peroxide will just cause a big wet fizz. You'd have more success trying to explode cow shit.

@ PhDman - conceivably they could have used a retort to try distillation, rather than an open saucepan on the electric cooker, but there do not seem to be any media reports of any such laboratory equipment having been found or purchased.

Hot hydrogen peroxide solution in contact with a metal saucepan seems to be a recipe for disaster.


As you point out, if they managed to avoid the H2O2 vapours from igniting anything else in the kitchen, In theory, they could have actually weakened the concentration of the 18% H2O2 hair bleach by simply boiling it.

The Forensic Explosives Laboratory seems to have demonstrated chapati flour and hydrogen peroxide detonations, but, not by using the alleged TATP detonators because that would somehow be "too dangerous".

One would have thought that they could have used remotely controlled robotic devices to assemble such an experiment safely.

Whether they actually demonstrated that the precise concentration of chapati flour and hydrogen peroxide solution, with the impurities and additives present in the 18% hair bleach that the failed bombers used, would actually explode like their experiments shown to the jury on video, is another question, which has been glossed over in the media reports of trial.

Earlier evidence from the forensic scientists demonstrates exactly what one would have expected to happen, i.e. that the some of the water in the chapati flour and hydrogen peroxide mixture preferentially evaporated over time, locally concentrating the H2O2 causing the mixture to nearly catch fire in storage.

I never was any good at science so I shall stand in awe of those who are.I'm just glad his flashpoint wasn't reached. Surely the main issue is that these dangerous people are living amongst us with at last report 1,200 under surveillance from MI5?
The public needs to have confidence in robust government, a government not constantly consulting "community leaders" or the MCB for permission to interview or detain suspects. The police service appears more and more like the old toothless guard dog (no disrespect to individual officers) During the frightening scenes of the cartoon protests they appeared to have perfected that cringing smile dogs have when reprimanded.Political Correctness has reduced the once proud police force to the scourge of motorists and those who sell antique collectable toys now deemed offensive. I feel I'm living in a parallel universe when guardians of the state and the citizen are so shamelessly stupid and ineffective......at worst traitorous.
It appears the government and laughably named "opposition" (which opposes nothing) are in the grip of global warming orgasm while the biggest threat to our traditional freedoms goes unchallenged and positively protected.

This information may help. Media reports on the exact make-up of the bombs have been deliberately kept vague as to the proportions and concentrations of ingredients (particularly of the hydrogen peroxide) to prevent anyone getting hold of a recipe easily. And the 7/7 bombs were not made entirely of TATP, they were in fact quite similar to the 21/7 devices. Again, full information has not been released in the interests of public safety.

@ Bob - There is no evidence that the two sets of bombs were very similar in construction at all, except that they come under the heading of Improvised Explosive Devices, carried in rucksacks.

Unlike the 21st July 2005 bomb trial, there has never been any mention of chapatti flour as the fuel for the main charges of 7th of July 2005 bombs. The implication has been that they were entirely made of TATP "Mother of Satan" or perhaps HMTD.

It seems that "full information" about effective bomb making recipes is already widely available via the internet, mostly on websites in the USA, which will present John Reid and Franco Frattini with insuperable problems if they try to censor them via existing UK or proposed European Union laws.

The properties of Hydrogen Peroxide, and what it does at various concentrations, and in contact with various organic substances, with and without the presence of metal ion catalysts, is well known, and is uncensorable, unless you want to create industrial and laboratory accidents, by banning all the legally mandated Control of Substances Hazardous to Health (COSHH) information and other health and safety regulations.

@ wtwu: What you say is true, full information can be found elsewhere. But that doesn't stop the prosecution in the 21st July case asking national newspapers not to print the full details in the interests of not making it even more available than it already is. Media organisations have so far complied, given that to get into detailed discussion of whether 58 per cent hydrogen peroxide mixed with chapatti flour will explode using 5g of TATP.
And for your information, the 7/7 bombs involved hydrogen peroxide mixed with 'a different organic material' (as said in court), detonated with TATP.
The reason being that TATP is very unstable and it's not a good idea to wander around with large amounts of it (ie more than 5g) because you will probably blow up before you get to your proposed target.

Hi Bob

If I said that the 'different organic material' used in the 7/7 bombs was pepper would you collapse laughing or agree?

Yeah pepper. Well thats what I heard too, but I don't know for definite. Then again you could be the person who told me that in the first place... [ie someone in the media]. We might finally find out when the new 7/7 suspects go on trial (probably not until 2009 at this rate).

The original charges in this case were reported as:

1. That, between 1 Jan and 30 July 2005, the men conspired together "and with other persons unknown to murder other persons"

2. That they "maliciously conspired together" to cause "explosions of a nature likely to endanger life or cause serious injury to property"

source:BBC 15/01/07

The second charge of 'conspiracy to cause explosions' was dropped towards the end of the court trial, a fact that only the BBC reported in its report of expert (defence) witness testimony of Professor Hans Michels of Imperial College London (who apparently funded his own experiments - because "he wanted justice to take place").

So if the 'conspiracy to cause explosions' charge was not viable (as the explosive devices themselves were not 'viable'), what was the murder weapon?

And who are these 'persons unknown'? They cannot be any of the other 'known' 37 persons charged & detained as a result of the police investigations into this case.

I find it amazing that citizens rebuke the police and intelligence agencies but do nothing to help them. If the government is inefficient and not doing the job the people need to stand up and fight for what is right on their own behalf. Arguing about whether a bomb is equal to cow shit or not serves no purpose and is an example of academic anemia. The larger issue being overlooked is the people who drive and perform acts against the UK. Most are not rocket scientists, just martyrs. Remember the word martyr. It has nothing to do with logic, science or normalcy.

@ Brian - true enough, however, by stoking up mainstream media hysteria with "anonymous briefings" by Whitehall or Police or Security sources, and by exaggerating the actual danger posed by the evil if incompetent plotters, the "police and intelligence agencies" or their political masters, are actually helping the terrorists to terrorise the public.

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