I was also making a bronze lintel. I had to take a silicon mould for the iron lintel so it was an opportunity to make one in bronze as well.
The process was much the same, but it needed to be made in two pieces because of the limit on the crucible size in the foundry. The mould was taken from the original wax and then a clever ruse with carpeting provided for the thickness of the metal. The photo shows taking the mould from the wax which has just been used for the iron lintel mould.
Eden (op cit) undertook the pour at SSW and welded the two parts together. I came in to fettle, chase and sand blast it. It is now at home in my studio awaiting final texturing and patina.
I spent several days fettling and chasing the iron lintel and cutting off bits that weren’t required. Eden (Senior Tech SSW) assisted with this process – giving advice and moving the piece around for me. He also finalised an ingenious scheme for affixing the piece at its final location.
The lintel just fitted into my van and with further ingenious thinking from Eden it was stowed in a manner that I would be able to get it out by myself (or at least with one other)
I took it over to Stoer and we unloaded it. Unfortunately the weather was changing so the noble lintel moving team called off moving it to the broch that day, but they got together later to carry it in. My heart-felt thanks to them.
We now await a decision on the final location so the lintel can be installed at the broch site where it belongs,
The day dawned bright and by lunchtime the mould was finally finished; Eden had mended the furnace and the ‘bull ladle’ was also fixed; the fork lift was in place to take the weight of the ladle; Michael had cracked the scrap iron (thanks Michael) and weighed the bags of coke and iron. Eden must have laid the bed of coke in the furnace when I was working on the mould indoors; the air blowers and gas tanks were in place. It was decided by the tech team to go ahead with the pour.
The furnace was lit and the air blower turned on to force the temperature up to melting point; the gas blower was turned on to the ‘bull ladle’ to heat it up ready to receive the molten iron when the furnace was tapped.
The photo above shows Michael adding a charge of coke and scrap iron to the top of the furnace. As the iron scrap heats it becomes molten and drops to the bottom of the furnace. When enough iron for the pour (over 65kg) is molten at the bottom of the furnace the bung is broken so the iron can run into the ‘ladle/crucible’.
The weight of the iron is taken by the fork lift and Michael and George manoeuvred the bull ladle into position and tipped it to pour the molten iron into the mould. There was a delay when the fork lift wouldn’t start and an alternative lifting device was tried before reverting to the fork lift.
Towards the end of the pour the bull ladle got caught in some way and the pour was aborted. The mould was showing metal through the air vents, so the general view was that the pour could be complete. The team have reviewed the equipment and made safety alterations since.
The metal needed to cool before I could peek inside, so I left it for the weekend. On Monday I removed the mould pieces to reveal an iron lintel, yeah
Thanks to Scottish Sculpture Workshop tech team and George Beasley.
The silicon mould and plaster mother mould that I took on the headland at Clachtoll made it safely to the Scottish Sculpture Workshop for the next stages.
Firstly I re-constructed the plaster mould so that I had one complete cradle for the silicon. Then I pinned the silicon into the plaster support mould and coated the inside of the mould with wax. I stippled the first layer on to capture the detail and and subsequent layers were brushed on to build up a firm mould a centimetre or so thick (thicker at the top edge) I then built the wax up as far as possible to remove undercuts on the inside.
I removed the wax wax from the silicon ready to start taking the resin-bonded sand mould.
I built a temporary box and used petrobond sand to build up the base to the wax. I did not do a good job on this, so had to make extra mould pieces at the penultimate stage (note to self to do better next time).
The resin-bonded sanded is mixed and rammed into the box around the wax, taking care to avoid undercutting.
When the top part of the bonded sand mould was complete the whole box was turned and the ‘rescue pieces’ added. The base of the mould could then be made.
This makes a particularly uninspiring photo (above), but it over took a week to get there.
The mould came apart as planned and was built up into the base and the top parts. I cleaned the joins: Michael (SSW’s assistant technician) helped with the core wash; I found the bars to hold it closed and Eden (SSW technician) working with George Beasley drilled the pour holes and air vents; the piece was moved outside; the cracks were glued; the pour cups glued on; the clamp bars put on and it was ready to pour.
Unfortunately I only have video footage of this stage so I can’t show it. The next post will show the pour.
2019’s open studios has been and gone. The weather was lovely and lots of people visited; and several people bought pieces or commissioned new work.
Commissions included a charm bracelet as a gift for a niece in Canada, which included a dolphin from the Firth of Forth; and a neck piece using an piece of carved peat that was a brooch from my childhood. I’ll show progress on this piece in a later post.
A sea water patinated bowl went to a new home as did a sea drift necklace.
It’s always good to show people my work and studio and I particularly like new commissions.
Finally I got a weather window to start work on the second piece of my residency.
We got a tent erected near to the broch, in the lee of the stones from the rockfall in the broch that the restoration project removed in season one. It was surprisingly easy to heave the stone lintel into the tent on Day 1 and surprisingly uncomfortable working in and out the tent. A lot of climbing in and out bent double and kneeling on uneven rocks was involved over the week. Some days were sunny and some grey and cold, nearly all were windy, with the wind battering the tent onto you as you worked.
So the process was:- firstly brush the bits off, then a layer of oil, which with hindsight was a bad idea; followed by a thin mix of silicon to pick up the details – because of the low temperatures and maybe insufficient mixing of the catalyst this seemed determined to follow gravity onto the groundsheet. However there was no choice but to continue, this time with a silicon layer with thickener. By then it was time to call it an end to Day 2. Although there were plans to return that night it was Day 3 that was spent putting on the third and final silicon layer with thickener. There was now a mighty fine silicon mould, but no way of knowing whether layer 1 had worked out.
Day 4 was onto the plaster and jute mother mould. I had a long and supportive conversation with the super helpful guy from Special Plasters before starting out. The first layer again seemed determined to make a mould of the ground sheet, but then we discovered that it was going off in the plaster puddles and this mix was perfect for the jute layers. I was paranoid that I’d make a plaster mould that couldn’t be removed, or carried out over the beach cobbles, so I designed a 6 part mould. I made little clay walls for each section and we filled them with three layers of plaster soaked jute with support straps.
When I removed the clay wall on each piece I oiled the surface and designed a wedge to ease the separation of the sections. After the third section there was a mishap with the scales and we swapped for a different set. This seemed to hugely improve the consistency of the plaster from there on; and the job speeded up because there was no need to wait for the pools on the groundsheet to go off. The number of sections meant that the work went on into Day 5.
However the plaster mould came off in sections as planned. Then the moment of truth, would the silicon mould have laminated, would the first layer have been successful? It was an anti climax, but a very welcome one, when it just lifted off and there it was, the first phase of a long process successfully completed. Perseverance paid off and I came away with a silicon mould that nestles in a plaster mother-mould.