As part of researching patents I came across one that claims to solve a problem that does actually exist. https://register.epo.org/application?tab=doclist&number=EP14188074&lng=en In broad terms a fire resistant door leaf made of "intuemecent transparent Gel Filled" fire resisting glass has "L" shaped trims bonded to the glass edges to conceal the internal seal within the glass that keeps the Gel in place. It is claimed that trims hide the internal seal if the side legs (bonded to the faces of the glass) extend 2mm past the seal. However in practice this only works when the glass is viewed "face on" perpendicular to the trim. If you stand prependicular to the leading edge of the door leaf (near the door handle) the seals are visible across the top and base of the door leaf and down the hinge edge of the glass door leaf. Another claim is that if the trims were bonded to the glass with a fire resitant adhesive, they would distort in a fire and break the glass. The invention says that by utilising an adheisive that debonds at high temperatures, the trims will fall off thus preventing the glass breaking. However it is a well known fact that glass in a fire goes into thermal shock, particulalry if the edges are covered (this forms a thermal shadow) keeping the glass edges cool and as the exposed central area of glass heats up the glass shatters. As this happens about 2 minutes into a fire test,the trims would not have expanded enough to break the glass before it was broken by the thermal shock effect, there is no benefit in the trims debonding as the glass still breaks anyway. So both the claimed improvements 1. concealment of the internal glass seal and 2. the prevention of the glass breaking are not achieved in practice. The EPO have however granted this. I cannot understand why as the inventive step appears to not have achieved the claimed improvments ? It appears that a patent does NOT have to work in practice for it to be granted. Seems pretty odd to me ? Logikman

2 Answers 2


Patent claims do not need to be for a production-ready version and do not even need to be a better solution than existing solutions, just different,

It needs to, at least minimally, be useful; it needs to be new; and in most places to have an inventive step beyond the state of the art. (In the US the similar requirement is non-obviousness.)

Other than in medical domains, short of a perpetual motion or time machine, an application is taken at face value. If a fairly useless invention is patented it’s not the end of the world. A patent is not supposed to be an endorsement by the government that something is a good solution.

If it doesn’t work very well it will not be infringed by others and it will not necessarily inhibit better solutions getting patented.

The work load to judge the practical value of patent applications would be very impractical and not really objective without universal criteria of merit.

  • The glass described is gel filled glass that normally uses standard glass. It always goes into thermal shock after 2 minutes in a fire test. A video youtube.com/watch?v=MyXJ8qgvmHY and patents GB1451932 GB 2195136A describe this. The trim cannot expand enough in the first two minutes to break the glass earlier (simple expansion theory based on the temperature rise in a fire test over the first two minutes). There really is no way the trim falling off will stop the glass breaking. It is the Gel becoming opaque that gives the glass its fire performance as each glass layer breaks.
    – logikman
    May 15 at 12:17

The document has had a long prosecution history and as far as I can tell still not granted as a patent. That said, I agree with George White, there are many patents which have little value and if they really don't work, then they should pose little difficulty to other products. In this case, the assignee has pursued the patent for the better part of 9 years and doubtlessly poured much money in to the prosecution. It is hard to believe they would do so if the invention has no value.

I would like to suggest, however, that you really dismiss the invention a bit too easily. Assuming that the glass will shatter before the trim falls off is assuming a lot. The adhesive might debond at far cooler temperatures than when glass might shatter. Also regular window glass likely acts far differently than specialized tempered glass used in fire doors.

Engineering is full of examples where mechanisms work in ways counter to intuition. Unless you have actually tested the invention, it is perhaps too much to claim it couldn't possibly work.

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