This is a different post than our usual sharing projects, products and colourful materials. We’ve watched for over 60 days, in horror and in heartbreak, at the violence and collective punishment of Palestinians in Gaza.
We believe in the importance of considering the human, as well as environmental, impact of what we do - the two are often intrinsically linked.
We’ve followed brave Palestinian journalists and writers like @wizard_bisan1 , @motaz_azaiza , @mosab_abutoha , @abod_bt77 , @byplestia , @eid_yara , @refaat17 (killed in an airstrike on 6th December), document their own genocide. We’ve witnessed the bombing of hospitals; schools; homes; refugee camps, cultural buildings; Entire families have been killed - grandparents, parents, children.
There are shortages of food, safe drinking water and restricted humanitarian aid due to Israel’s blockade of Gaza. We’ve witnessed Palestinians trying to dig their family, friends and neighbours out from under stories of rubble with their hands and hand tools. What we’re witnessing is a catastrophic loss of life and it has to stop!
Millions and millions of people around the world have been protesting, week in and week out. We want to join other artists, small businesses and cultural organisations in calling for an immediate ceasefire in Gaza. Palestinians, like all people, deserve to live a life free from airstrikes, blockades and occupation.
Be brave and join your online, local and national actions calling for a ceasefire!
The sun came out for us on what was a very special day testing the tile layout for the Cairns Street façade of the Fourth Corner, a new building in Granby developed by @granby4streetsclt and designed by @assembleofficial
These are 3536 of the 8804 hand-glazed tiles that will be installed in the first use of the super
low-carbon devitrified ceramic tiles developed with @matter_at.hand
It was an opportunity to see them at the scale they’ll be used - it’s difficult to visualise this when you’re looking at individual tiles or small batches.
The colour palette draws on the neighbouring brickwork – on Cairns Street façade it’s a blend of terracotta shades and the Granby Street side will be light yellows.
We were joined by people from Cairns Street who laid the tiles with us - both magic and a great help as it was definitely a bigger undertaking than we’d anticipated!
It feels very special to develop the next material chapter of the Workshop for the Fourth Corner - honouring our origins, from Liverpool 8 to the world.
We love creating colourful tiles - it’s a core part of what we make but, some of the raw materials used to create bright colours can be extraordinarily damaging.
As part of the development of our new range of devitrified ceramic tiles, we set ourselves the challenge of creating vibrant colours with pigment recipes that avoid the most damaging
minerals like cobalt, cadmium and rare earths that are often relied upon in ceramics.
While no material is perfect, we focused on common metals like copper and chrome in search of bold blues and greens without cobalt. For reds and yellows, we explored various forms of iron in place of cadmium and praseodymium.
A fascinating process of testing and refining colour possibilities @matter_at.hand . We can’t wait to share more!
Devitrified ceramic tiles, on SEM cyanotypes that show the microscopic crystals that grow and reinforce the body.
The tiles use waste glass in multiple states, single fired at a very low temperature. The ‘body’ is devitrified ceramic - formed from the reactive crystallisation of waste glass. The ‘glaze’ is a combination of the waste glass with a super fluid frit that prevents it from crystallising (keeping it glassy). There is also a ‘grog’ in the body made of larger grains of waste glass, that helps with drying & shrinkage.
Waste glass plus a mix of reactive additives, mixed, extruded and cut into shape - then fired. In the heat, the waste glass softens, crystals grow and the mixture transforms into a super dense + durable ‘devitrified’ ceramic. Equivalent to porcelain stoneware - but using a lot less heat + energy.
But, having practically no clay to speak of makes the actual forming of tiles a lot more difficult. We couldn’t swap it into the normal production process at Granby Workshop and in the end we had to fully embrace the unruly way it behaves and redesign the process around it - borrowing ideas from many other worlds of no-clay forming - from egyptian faience to fondant icing :)
From household glass waste to ceramics. The dusty impure fraction of recycled glass ‘devitrifies’ into a ceramic material at 700ºC - 800ºC, using a lot less heat than conventional clay-based ceramics.
But it’s an unpredictable process - since at the same temperature the crystals grow in the glass, the body softens and slumps – resulting in floppy saggy tiles.
So - I tested a lot of different clays, fillers, wastes and reactive additives that we could use mixed within the glass waste – providing a skeleton to hold its shape, a scaffolding to guide crystal growth and a way of controlling the properties of the material.
1 Pressing test tiles from recycled glass
2 Test tile under the scanning electron microscope before firing
3 Lots of tests
4 Pure glass waste, devitrified
5 ‘controlled’ devitrification
6 Lots of tests
7 Lots of tests
The crystals that grow in glass. Each little impurity in glass can act as a seed for crystals to grow when heated. As the glass slowly softens, these crystal ‘flaws’ fan out and can create a network that reinforces the glass, transforming it into a form of ceramic.
The 18th C French scientist Reaumur was convinced the secret of porcelain lay in heat-treating glass objects like this – packing bottles in sand and reheating them over several days until they emerged frosty white - creating a material known as Reaumur’s porcelain and one of the earliest intentionally devitrified or glass-ceramics. The same crystal phases that Reaumur noticed (known as devitrite or reaumurite) have also been found in glass objects altered by volcanos and fires.
Reaumur’s porcelain never really took off because the long heating meant it was prone to sagging – but 200 years later glass-ceramics have developed into a whole field of high-performance materials, with super engineered compositions for everything from phone screens to dental crowns.
1 Crystals growing in reheated mixed glass waste, scanning electron microscope
2 Processing mixed glass waste and reheating to crystallise
Glass can in theory be recycled endlessly. The perfect closed loop for a spaceman economy. Nothing added or taken away apart from the intense heat and cooling that drag it back and forth between solid and liquid.
But what about the dirt that gets in?
Bits of metal, rock, ceramics, debris, grime, dust – imperfections and the reality of waste collection - all create discontinuities. Small structures trapped in glass’s otherwise perfectly structureless matrix.
These unwanted intrusions in turn cause crystals to grow - ‘devitrification’, turning glass to not-glass-anymore and a big problem for glassmakers.
So, of the 1.5 million tonnes of glass that gets recycled every year in the UK, about a third - 500,000 tonnes - is too impure, or in pieces too small, to be effectively sorted, cleaned and turned back into new glass again.
So this ‘98% glass’, a material still with enormous capacity, is not remelted but used as a low value filler in pipe bedding and construction aggregates or as a grit for cleaning.
1 Reheated glass
2 Mixed glass from household recycling
3 Partially devitrified mixed glass
4 + 5 The processing of UK mixed glass waste
Pig, cow and lamb carcasses, after the fat has been separated, pulverised, dried and crushed 🤢 Since the spread of mad cow disease 30+ years ago, it’s mainly incinerated - 230,000 tonnes were burned in 5 UK power stations, leaving more than 60,000 tonnes of meat and bone meal bottom ash.
It’s been about 200 years since bone ash was first used for bone china, but long before that it was used by humans to make pigments, to make glass white, to purify gold and silver, in medicines and as a nutrient for crops.
Straight from the power station, it has a kind of sandy consistency, but once its milled it breaks down into microscopic rod, plate and pill-like particles that have a big surface area and when mixed with a bit of water give a super smooth, sticky texture – almost like an animal clay.
It’s kind of amazing that a material so raw and disturbing can transform into something with the apparent purity and brightness of something like bone china (pic 3). But – since phosphates like bone ash are so scarce, the most important use of it is to return to the land as a fertiliser.
1. Ground meat and bone meal bottom ash under SEM
2. How the material arrives from the power station
3. Tests of a bone china-like material combining the mbmba with recycled glass and other waste streams
4. A fracture surface under the SEM
Millions upon millions of black bin bags of household rubbish, burnt, to reduce landfill and generate electricity, leaving behind this dusty grey gravel known as incinerator bottom ash.
The contents of one bin bag to the next are completely different, but when viewed from afar, at the scale of a city or region, it all evens out. About 30% paper & card, 25% food waste, 20% plastic (and still increasing), and all the other stuff - metals, wood, textiles, glass, appliances, batteries, coins, things cleared out or accidentally chucked.
All those individual decisions about what to keep and what to discard, condensed and recorded in energy and 2.7 million tonnes of ash per year. It is, for sure, one of the major new mineral deposits of our age. It’s mainly buried beneath our roads: new geological strata that trace our travel routes.
It’s a mix of ‘parent’ materials that survived incineration, like broken plates or bottle caps, alongside new ‘child’ materials that occurred in the volcano-like conditions of waste incineration – reactions that create salts, compounds, glasses and gas.
The first image is a pixel-by-pixel scan of its chemical composition at a microscopic scale, where each element is represented by a different colour. It contains 35 different elements - nearly a third of the periodic table in less than 0.2g of powder.
This waste of the waste contains traces of elements dug up all over the world - copper, zinc, lead, nickel, antimony, europium, zirconium, strontium…
For ceramics – it could be used, but salts in it and the amount of calcium carbonate means it’s not without its drawbacks, and there are plenty of better materials out there.
As a way of getting rid of our rubbish – it’s kind of terrifying. It’s better than straight landfill in a lot of ways – good that some energy is generated - but who knows what long-term effects burying more and more of this under our roads will have on our soil and our water. Those heavy metals and contaminants are no longer confined to registered sites but are being spread out everywhere.
Straw bottom ash: a Bizzaro material. Jet black, bubbly foam glass, created in power stations. A by-product of burning straw to generate electricity.
Its composition depends on the soil, on fertiliser, on the weather and on our diet. In the UK, we like wheat - which leaves straw rich in silica and potassium. This is a recipe for a sticky, molten mass when it’s burned (potassium acting as a flux to melt the silica).
This gloopy lava-like liquid traps unburnt carbon (black) and the gases released from burning (bubbly), before supercooling and solidifying into an accidental glass - 55,000 tonnes per year of it.
Under the electron microscope, you can see its glassy, conchoidal nature. X-Ray Diffraction shows only tiny traces of crystalline phases. It’s a glass, made in a fire that you could reheat, reform and blow.
For ceramics - it’s basically already a frit for glazes, could be sintered or used as a body flux to reduce firing temperatures. For other fields it can be ground up as a pozzolan ala roman concrete or used as is since all the bubbles mean it’s a pretty good insulator and lightweight aggregate.
But, it’s just crazy to be burning all this straw for electricity – releasing all the CO2 absorbed by the plant that could otherwise be stored – and losing all of that useful material. The 887,884 tonnes of straw burned in the UK (Ofgem, 2021) is enough for more than 120,000 fully insulated straw bale homes to be built each year, if we did that instead.
1 + 2. Straw bottom ash, from UK power stations in Cambridgeshire & Lincolnshire.
3. Fracture surfaces of individual grains under the scanning electron microscope (about 10 µm across)
4. Reheating + processing ash.
5. A straw bottom ash tile, made by pressing powdered straw bottom and sintering to 750ºC
6 + 7 . Reheating the ash to 1100ºC (the trapped black carbon bubbles off as it re-melts) leaving quite a clear glass.
