I noticed a few things which I'd come across before but that viewing in a group reveals as consistent and so important.
The first is the 'three-dimensional' frames he uses within pictures. His canvases are typically quite gloomy, as if artificially lit, and consequently these boxy, thin-but-solid scaffold-frames are picked out in white. The viewing notes pick these out as well:
Figures are boxed into cage-like structures, delineated 'pace-frames' and hexagonal ground frames, confining them within a tense psychological zone. In 1952 he described this as 'an attempt to life the image outside of its natural environment'.I think that this removal from it natural environment is already achieved in the very artificial, stagy manner in which the pictures are set. The 'space-frame' gives something more. For me, that is the suggestion that the figure at the centre of the picture is suspended, free from gravity, free from contingent ties to it's own self - rather like a carcass or flayed skin floating free of the density of 'person'. With the void represented in the gaping black mouths of so many subjects, this makes for an interesting effect. There is nothing withint and nothing without.
Many of the exhibition's earlier pictures also have vertical stripes or streaks over the figure and often panning out at its base. This suggested to me the PvC strip curtains familiar from a butcher's or an abattoir, separating one working area from another. This is a more minor observation - I'm not sure if such partitions were commonplace in the middle of the last century - but I found such a connection striking given the carnal nature of Bacon's subjects and allusions.
Bacon's art is clearly highly visceral and honest, trying to expose the nature of being human. Most subjects are painted in isolation from the world (even before the framing or empty-core inventions mentioned earlier). Bacon's figures have their own take on the three-in-two dimensionality of Picasso/Braque's cubism, rather like photographs with multiple or long exposures.
More interestingly these figures are sometimes shown within their own shadow, as if placed in a cut-out space too large for them. They have their own penumbra.
As a strange corollary to this, many later works - the Dyer memorial pictures and a late portrait of John Edwards (1988) - cast their own shadows on the foreground.
But both the black halo-penumbra and the bright foreground shadow come over as materially part of the subject. It is as if the ark outlines of a subject suggests an alternative person: the inauthentic as Heidegger (et al.) has it, or a Doppelgänger. The colour bleed of the foreground shadow is just that - an extension of the subject oozing into the unoccupied space before them. The overall effect is one of precipitation. The precipitation of the void into the person that is the subject; the precipitation of the subject into the surface of the painting.
It would seem that the framing devices that are part of the content of the pictures are meant to dissociate the subjects from everything - the viewer, the picture, the world of their situation, scrupulously limited though it is. At the same time it seems that the shadows from which and by which the subjects are cast do precisely the opposite precipitating figures from an unknowable void and casting the very stuff of the figure into the physical experience of the viewer.
These are daring existential experiments. There's a very economical canvas in the final room that achieves this technically if not particularly elegantly. Blood On Pavement (1988) is simply that. But looked at close up, the paint of the upper pavement has run down into the patch of blood. Blood On Pavement, or pavement on blood?
For this reason as well has others above, I'd recommend a trip to see this exhibition (I read Laura Cumming's piece from last Sunday's Observer Review prior to my visit, which I can recommend).