The Z Stack

As well as the vesicles, a major glass element of the sculpture was the Z Stack, as I like to call it. This is a form made from ‘slices’ of glass, each with a different colour or texture, that when mounted together suggest a three-dimensional form.

The Z Stack was an element that came to mind very early in the process during my visit to the labs, when Arindam explained to me how the images of the ‘spheroids’ of cells were constructed. The confocal microscope could be instructed to scan multiple layers of a three dimensional object, and would then build an apparently three dimensional image from the slices it had scanned. The number of scans that go into constructing the image would then affect the resolution of the object and also the time to create as well as the ultimate file size.

A non-glass mockup of a Z Stack – my first experiment with the idea

There are two main textural types of slice in the Z Stack – those with ‘miniature vesicles’ on the surface, and those which have a honeycomb structure. The honeycomb is the one reference in the piece to the original source of the peptide, the Amazonian wasp.

I wanted to create an analogue analogy for the Z stack, to create a 3D form from slices, and from that my Z Stack was born. Initially I thought it might be interesting to make the slices ‘floppy’ to accentuate the departure of the analogue from the digital counterpart, but aesthetically I found it confusing and cumbersome. I also wondered about offsetting some of the slices from the horizontal, but again this appeared to confuse the communication of the idea.

In the later stages of construction, I continued to experiment, but this time with the number of slices to see what worked best in creating an outline form. Below is the version with 9 slices.

I ultimately settled on 11 slices as giving the most pleasing form.


Once the vesicles were underway, one of the major considerations in creating the piece was the relationship between all the different elements. I had already, obviously, committed to creating the ‘vesicles’ and ‘z-stack’ at certain sizes and imagined them situated in relation to each other, but there was still quite a lot to be considered in getting the relationships right. There was also a lot of planning and experimentation in creating the fixings to hold the glass in position.

Once I had a sense of the sizing and spacing, I set to constructing the base and the stands that would hold the glass elements. I was also trying to take into account that the piece would need to travel from my studio to the hospital in Leeds, so my aim was to make the piece so that it could be deconstructed again for transport.

Meanwhile, the case I had ordered to contain the diorama had arrived. This meant that I could make sure that all the measurements I had made were accurate and that the base and the case would fit together properly.

The slats at the back of the base would hold the acrylic sheets used to mount the backdrop images. These had to be carefully measured so they would hold the sheets firmly in place.

Eventually the base was built, and I could mount the stands that I had created to hold the glass elements and acrylic sheets. At this stage, I was working with the acrylic sheets still in their protective wrap – that only came off close to completion as acrylic scratches very easily. In fact, the case for the piece has been treated with an anti-abrasive coating to try and minimise exterior scratching, although it can’t prevent it altogether.

And now, all that was left to do was to spray paint the base and mount all the interior elements!

Making vesicles

I knew from quite early on that I wanted my ‘natural history’ diorama for the peptide/membrane project to feature several globe forms which inspired by the vesicles / cell membranes under the influence of the peptide. (The peptide itself would be invisible – only detectable in its effects).

The vesicles were not intended to be a scientific representation, but more something between an evocation and an abstract sculpture. Having said that, there were a number of concepts that I had found really interesting from the time I spent in the lab that I wanted to inform the development of the vesicle elements, so I set about playing with ideas and techniques that would take on those ideas.

Creating Surface: While I was in meetings and labs with the team, I kept hearing about phase separation. In fact, to begin with i wasn’t sure if i was hearing about ‘phase separation’ or ‘face separation’, but that was soon cleared up! During my time in the labs i looked at images and heard more about this phenomenon in cell membranes and was fascinated by the confocal microscope images that illustrated it.

‘Spotty’ vesicle showing phase separation – image captured by Andrew Booth

I started to play with frit balls as a way of creating different surface effects within pate de verre. Frit balls are small granules of glass which are heated in the kiln to contract into little balls. I started to incorporate different sizes of frit balls into pate de verre samples in different ways – mixed in or adhering to the surface in groups. It was fun and I got some effects i really liked.

Once I had settled on some textures i liked, i started making vesicles. Initially I used rough textured spheres around which to make moulds, but I then moved onto using wax spheres that were smoother and easier to work with.

Colours: The first vesicle I made, i mixed up my colours and ended up with a vesicle with big pink patches which i hated. The plan had been for a much more subtle transition from white to a pale fleshtone, not only to evoke the biological but also in keeping with the overall palette that i’d talked to the Leeds team about, having seen the space and the way colours worked in the CRF area. This first patchy vesicle made a good test piece to try out the effects I wanted to develop using perforation, poration and metal mesh.

Through further experimentation and refining my process I finally got the three colours and textures of vesicles that I wanted.

The three final vesicles before I started drilling

Drilling: I decided to make the perforations in the vesicles by drilling into the globes rather than making the holes through the mouldmaking. Several reasons for this, including the likely strength of the ultimate vesicles and also the accuracy of the holes. I did, however, for the darkest vesicle, identify where i wanted the perforations to fall and created bulges around them as part of the model and mouldmaking process. Luckily the drilling went well and there were no breakages at that stage, which would have been heart-breaking as well as vesicle-breaking, as by this point, each vesicle represents many hours of work. Now they have been drilled, the white vesicle has no pores, the pale flesh vesicle has small pores, and the larger darker vesicle has extensive perforations.

So that, in a nutshell, was the development of the vesicle elements of the pieces. There’ll be more vesicle chat when I get to posting about the process of making the mesh elements that emerge through the perforations to create the overall effect of leakage, inspired by the action of the peptide…