Bleigiessen is described on the Wellcome trust page as follows:
Consisting of 150 000 specially processed glass spheres, suspended on almost one million metres of fine stainless steel wire, the sculpture glows with a constantly shifting rainbow of colours. This effect was created through a unique process of sandwiching reflective 'dichroic' film within the glass.So Bleigiessen's organic forms turn out to be from a happy accident with molten metal, rather than the DNA or biological roots I had naively assumed given its Wellcome Trust connections. I like that. More background on Heatherwick in this great PingMag feature.
The form of the sculpture has been derived, through the use of 3-D computer modelling, from the twisted shape of a drop of molten metal, which cooled and solidified as it fell through tumbling water. The aim was to produce a sinuous, curvaceous form with variety, so that it would look different from each of the building's nine floors.
Since it's on UCL's doorstep, I've admired the sculpture from the pavement several times before, and I wasn't alone in having my nose pressed up against the glass when it was under construction. Inside though, the ambition and scope of the work becomes clear.
Bleigiessen's thousands of steel cables render its interior an obscure and enticing mystery, strobing in and out of view as the layers of cables overlap. To me sculpture is art manifest by space and requiring movement to explore and enjoy it, and so Bleigiessen is the anti-sculpture in that it demands stillness from its viewer. Tilt your head up and down to take it all in, by all means, but don't cross its overwhelming verticality.
Well worth the trip, the only downside is that the fast and smooth glass lifts don't linger alongside it for long enough. Tours are currently running on the last Friday of every month, the Wellcome Trust site has the details.