Mixing the Mortar

I was down at the dry store early this morning to see a batch of the mortar being mixed for use in the continuing task of stabilising the stone walls in the north range.  The store is a quarter of a mile from the site, and I was there to meet....

....Iain MacPhail, one of the workmen whom John-Paul had described as being very good at this task.  Iain - pictured here earlier in the year -  is a local man, from a crofting family in the small township of Achnaha in the centre of the peninsula.  Sadly, Iain wasn't there - he'd had to go off to see the dentist at short notice - so John-Paul stood in for him.

Everything is extremely efficiently organised for the task, one which, in so many ways, is just like cooking.  There's equipment, in this case a pan mixer, 1, there are the ingredients - 2 is whin stone and, in the sealed bucket, lime putty, 3 is hydraulic lime in a bag, 4 is the Durham beach sand, and 5 is a bucket of water - and then there's....

....the recipe, neatly pinned up on the wall with simple, step-by-step stages.  At present, because there are only three men working on the pointing, they're making a half load which lasts them all day.  In summer, they'd be making a mix every couple of hours as that's the working time they have in warm temperatures, but at this time of year, with the temperature lower and the air damp, they have up to two days working time on a load.

First to go in was the lime putty, which very much resembled cream cheese, followed by the whin stone.

The pan mixer had these blended very quickly, the mix looking very much like a cake with currants.

The other ingredients followed quickly, care being taken at all times to make sure the mix never became too dry.  It all looked incredibly easy, but I have a nasty suspicion that this was only the case because J-P has done this a few times before.

A lot of care was taken towards the end, as the last of the sand was added and then just enough water to get the perfect consistency.  A quick test is to take some of the mix out on a trowel, and then hold the trowel upside down: if it sticks, it's right.

Here, chef John-Paul is seen beginning the process of removing the mortar from the mixer.  It's put into plastic buckets, and these are then sealed until they're ready to be used.

This last picture shows the mortar loaded onto the little, all-purpose dumper truck to be taken over to the castle.

Winter Morning

A winter morning, looking down the Sound of Mull from the castle.

Who Built Mingary Castle?

Before you turn away - no, I'm not reopening the argument about whether it was the MacDonalds or the MacDougals who built the castle.  The question I'm asking is a little more down-to-earth, because the real builders were, of course, the workmen who, some time around 1300AD, spent at least three years, probably in some pretty hideous conditions and almost certainly in some terrible weather, constructing it.

There are two basic possibilities.  One is that Mingary was a local product, with a local design responding to local requirements, and built by local workmen using local techniques which had developed over a long period.  Ross Cameron of Addyman Archaeology, who came all the way down to Kilchoan last week to give us a thought-provoking talk on the dating of West Coast castles, subscribes to this view - and his arguments are very cogent.

The other possibility is that it was designed by someone who was a specialist castle builder, who travelled round building castles, such as Castle Tioram, above, albeit taking into account local design requirements, but used techniques he had largely learned elsewhere.  He may have brought with him some specialist workmen, though he probably used local men to do the heavy work.  Then, of course, there's a full spectrum between these two possibilities.

I confess I liked Ross' argument, that the castles of the west coast show little affinity for castles elsewhere in Scotland, and certainly no design connections to Norman-English castles; and that the Highland Scots had plenty of previous experience in building large stone structures.  I liked Ross' argument until people began to talk about the mortar used at Mingary.

I was fortunate enough to spend some time recently with Francis Shaw, the Mingary Preservation & Restoration Trust's architect from Shaw & Jagger Architects, while he talked about the mortar.  It is very unusual, and finding it at Mingary shines a new light on who built the castle.  Francis has also written about it, and this is what he has to say:

"The mortar is similar to 'Roman Concrete' requiring both the use of hot lime and hydrated lime reacting with a pozzolan - in Mingary's case, whinstone. The mortar's structural integrity is ensured by its rapid curing, making it possible that Mingary was built in two, three or four years.  This is significantly less than the timescale I first believed, of circa seven years.

"This building technology is generally believed to have been 'lost' after the fall of the Roman Empire, being rediscovered with the discovery and translation of Vitruvius (around 1414AD).  The evidence from Mingary's mortar (around 1300AD) makes it clear that this was not the case. The mortar used in contempory buildings in England does not appear from evidence to use the reactive quality of the two limes in conjunction with the catalyst properties of pozzolan.

"My views are speculative but I believe this construction methodology was either imported into Scotland in the late twelfth or thirteenth century from the Middle East, possibly during the collapse of the Kingdom of Jerusalem between 1265 and 1291, or the only other hypothesis is that construction methods had survived in the Highlands from the time of the Roman occupation."

Francis' ideas suggest that someone who had, perhaps, worked on castles for the crusaders in Palestine, such as Krak des Chevaliers, above, and learned there the use of Roman concrete, later returned to Scotland and was involved in building Mingary.  I would love to know whether any other contemporary castles, particularly along the west coast, have the same mortar.  If they do, then the idea of an itinerant, ex-crusader master castle builder becomes more likely.

Photo of Castle Tioram courtesy Dave Wilkie on Wikimedia Commons, link here.

Photo of Krak des Chevaliers courtesy Wikipedia, here.

Many thanks to Ross Cameron and Francis Shaw.

A Turning Point

Winter has arrived.  Last night the wind swung into the north and brought in frequent hail showers.  By this morning, the wind had dropped but light flurries of snow were drifting out of a grey sky.  But, with the snow comes excellent news from builder John-Paul Ashley of Ashley Thompson.  While his men are still working on cleaning and stabilising the stonework on both the north range and the battlements, his stonemason has started pointing in the main range.

Pointing, for those who are as ignorant as I, is pushing mortar in between the stones to replace the mortar that's been eroded away through the ages.  This is a turning point for Mingary Castle because it signals that the process of rebuilding this great monument has begun.

Great care has been taken to keep as many of the individual blocks of stone in their original position as possible, but many of them are very precarious.  A good example is this huge stone lintel which stands over one of the fireplaces in the north range.  It was okay at the nearer end, but at the far end it was teetering on a few pieces of rock.  It's now stable.

This wall, part of the central gable, is another example of an original wall that's been saved, and been stabilised following pointing.

In the same way as there are hundreds of different cake mixes, the mortar mix J-P's men are using has a 'recipe'.  It consists of:

1 part hydraulic lime
1 part lime putty
        - for anyone who wants to read about the basics of different sorts of lime, click here.
7 parts Durham beach sand
2 parts whin stone.

Mortar takes time to 'go off' - harden - and it's helped if the atmosphere is warm and dry, so all the windows in the north range have been fitted with polycarbonate sheets, the sort of thing that's used on conservatory roofs.  In addition, two pot-belly stoves will be at work in the near future.

It was cold for the men working in the building this morning.  I joked with them that, shortly, it'll be as warm as a sauna.  They weren't convinced.

The Castle in its Landscape

These pictures, taken last weekend from Beinn na h-Urchrach to the east of Mingary Castle, give an impression of the landscape in which it stands. Much of the western end of the Ardnamurchan peninsula is wild, open moorland covered in coarse grass and heather, which supports sheep and red deer.  The few areas of better land tend to lie in pockets along the coasts.  The valley in the foreground here, that of the Allt Choire Mhuilinn, is an exception, and we have plenty of evidence that it has been occupied since at least Neolithic times.

The stripes that run down the hillsides are evidence of relatively recent workings, the rig and furrow system used by the local people for years until the Riddell family set about 'improving' the Estate in the early 19th century.  The clachans' stone walls, like the one that weaves across the land at lower right in the picture, were replaced by the higher, more substantial walls of the sheep farmers, one of which can be seen just to the right of the castle.

This relatively fertile valley runs some four kilometres inland and is at least two at its widest - this picture is a continuation to the right of the one above.  For a castle such as Mingary to exist, it needed a reliable source of food to support both the MacIain laird who held it as his seat from the early 14th century, and the many retainers who depended on him.  While the other West Ardnamurchan clachans - the small, communally-run settlements occupied by MacIain clan members - would have contributed to this, one can see that the the castle might have been heavily dependent on this rich valley, which was occupied by three clachans, Mingary, Choire Mhuilinn and Skinid.

This map, held by Ardnamurchan Estate, shows the area covered by the photographs.  It was drawn by mapmaker William Bald in 1806, shortly before the improvements began.  The fields of the three clachans are coloured - red for Mingary, yellow for Skinid, and blue for Choire Mhuilinn.  Bald was a meticulous mapmaker, and the size, in acres, of every field was marked, as were the houses occupied by the clanspeople.  His map is, therefore, a record of a way of life that had almost ceased to exist fifty years later, by which time most of the people had either left Ardnamurchan, many to go overseas to places like Canada, the US, Australia and New Zealand, or had been moved to the new crofting townships.

Under the Weather

This picture was taken on Sunday, from Beinn na h-Urchrach, a ridge to the east of the castle.  It was a stunning Highland early-winter day, with light southeasterly breezes, wall-to-wall sunshine, and air so clear one felt one could reach out and touch the distant hills - that's the island of Coll, thirty-five kilometres away, lying along the horizon.

Since Monday, with the start of the working week, the wind has gone round into the west, freshened and brought in some stormy weather.  So this morning, when I went down to the castle to catch up with progress, the men were working in a stiff force four which gusted, in some vicious hail showers, to force five or six.

To add to builder John-Paul Ashley's woes, the dumper has broken down.  In normal circumstances, it probably wouldn't take long to get a piece of machinery like this fixed, but we're miles from anywhere, down a single-track road, so access to parts and servicing is a real problem.

As can be seen from this picture, these westerlies bring in as many sunny intervals as they do showers.  Scaffolder John Forsyth is back on site.  While he has more work to do in the courtyard, he's started by putting up scaffolding in a number of places so the the workmen can reach all the castle walls.  Yesterday he completed the scaffolding against the north range's western chimney - on the right in this picture - the only one of three which was still standing when the job started.  It will be stabilised and repointed as soon as possible.

Some of the men, including Johnny O'Neil, pictured here, are continuing the slow job of clearing the loose mortar from the exterior stonework, where they're exposed to the full force of the weather. To survive a working day in these conditions, it's essential to be appropriately dressed.

As I was leaving, the men were taking a well-deserved morning break in the portkabin, and what impressed me was the cheerful atmosphere as they sat around the table drinking their tea.

The Window Problem

Formal application for a change of use of Mingary Castle, from a ruin to a dwelling house, has been with Highland Council, the local authority, for some weeks.  The Council visited the site on Tuesday and carried out a tour of inspection.  A decision is imminent.

Meanwhile, discussions continue between the Trust's architect, Francis Shaw of Shaw and Jagger, and Historic Scotland.  Francis was kind enough to give me some of his valuable time on Tuesday to describe the complexity of some of the decisions that have to be made before work can progress.  For a start, agreement had to be reached on the date that the restoration will reflect, and this will be the last time the castle was in use, some time in the 1770/80s.  The last known refurbishment of the north range (shown in the photo below, before work began) took place some around 1700, and there is no indication that any major works were carried out between then and 1770/80, so the designs need to reflect the styles of the years around 1700.

Once this was established, the form of a huge range of features has to be agreed - and a good example of the problems faced is the windows in the north range.

The windows today are gaping holes.  There are no surviving pictures to show what they were like and, to complicate matters, the design of windows was changing very quickly in the late 17th and early 18th centuries.  Prior to 1696, because the technology didn't exist to make large panes of glass, the norm was for many, small windows.  In that year, the government brought in a window tax based on the number of windows in a building, in three bands: 0-10, 10-20, and more than 20 - the north tange would have been in the middle band.  While a window tax wasn't applied in Scotland until 1748, Scotland's position in the forefront of Classical design, and the changing technology which allowed bigger sheets of glass to be formed, would have influenced the decisions made at Mingary.

If the refurbishment took place between 1696 and about 1720, then it would have been carried out by the Campbells, who had received the castle from the Duke of Argyll.  They are likely to have put in cross casement windows - the sketch gives some idea of what they would have looked like - with leaded lights.

Had the work been done a little later, the then owner, Sir Archibald Murray of Stanhope, would probably have used sash windows with thick glazing bars, both upper and lower window being divided into perhaps 16 panes.

If these are the considerations when making decisions about the windows, there must be hundreds more about other design features in this building - and the other two buildings, which are not of the same age and had very different uses.  The example of the windows gives an insight into the difficulties faced when restoring an historic building like Mingary Castle.

Many thanks to Francis Shaw for his help.

A Cold and Wet Day's Work

You'd never know, from the smiles on the faces of builder Ashley-Thompson's workmen, that the weather on site today was wet, windy and chillingly cold.  Pictured are Iain MacPhail in the foreground and Johnny O'Neil in the yellow waterproof, and they're busy on the battlements of the north curtain wall.

This site works in all weathers.  At present the men are clearing out the roots of vegetation which, over the last two centuries, has forced its way deep into the exterior stonework.

The battlements here aren't part of the original castle but were added some time around 1700, so the mortar they used wasn't the magical stuff of four hundred years earlier that has held the place together so well.   Despite this, the battlements are in much better condition than was expected.

The methods used by the castle's builders are becoming visible.  The walls were constructed by facing them with blocks of good-quality stone, then infilling the gap between with smaller stones and rubble, held in a mortar mix.

In places, this mortar mix is still in good enough condition to be left and incorporated into the build.  Any rocks which are loose, whether it's the big rocks on the walls' facings or the rubbly ones inside, are taken away, cleaned, and will be put back when the rebuild starts.

Meanwhile, builder John-Paul Ashley continues to experiment to find the right mortar mix for the exterior castle walls.  He's had another go at repointing a wall, and the results do look very good - even in the pouring rain.

But there's a long way to go, and a lot of discussion, before a decision is made as to which mortar they'll use.  One option which is being actively considered is a hot mix mortar, which involves the use of quicklime, where a reaction with water produces a mortar which is hot and will set in any weather - and set very hard.  It's probably what the original builders used, it's ideal for the sort of conditions we have on the Mingary site, but, unless great care is taken, it can be dangerous stuff.

Many thanks to John-Paul for taking me over the site today.

Winter's Coming

We're now moving rapidly into winter.  The winters here are dominated by the prevailing southwesterlies which draw in mild, wet air from the North Atlantic.  October and November are characterised by squally showers, sometimes of hail, and bright sunny intervals, but recently it's been more of the showers than the sun, with a rainfall total for the last week in October of just under 70mm.

The first thing one notices when arriving at the castle after a break of a few days is that the working area in front of the building is neat and drained, not the soggy quagmire it could so easily have become.  This is largely due to the loads of rock which were spread across it, which allow the rainwater to percolate through.

The wind was a blustery force 5 when I climbed the scaffolding, but the walkways, although wet, aren't slippery, and the railings give one a sense of security.  Most of the scaffolding in the courtyard is complete, though the scaffolders are due to return in a week to complete the job.

While I was on the highest scaffolding the wind suddenly picked up, gusting towards gale force.  As a wall of sleet hit the structure the whole scaffolding framework reverberated and the boards underfoot hummed.  A retreat to the down-wind side of the castle brought some protection, but working in those conditions would have been impossible.

Last winter Ricky Clark, who lives in one of the nearby Mingary Cottages, recorded a gust of over a hundred miles an hour.  It'll be interesting to see how the structure survives in those conditions.