HOTMIX! Nybrent Hyllestadkalk leskes og testes som restaureringsmørtel på Stavanger domkirke

George Murphy er spesialist på restaureringsmuring. Her tester han mørtel laget fra nybrent Hyllestadkalk på Stavanger domkirke i oktober 2017. Foto: Per Storemyr

George Murphy er spesialist på restaureringsmuring. Her tester han mørtel laget fra nybrent Hyllestadkalk på Stavanger domkirke i oktober 2017. Foto: Per Storemyr

Endelig i gang med hotmix! Med lesking og testing av nybrent Hyllestadkalk til bruk i mørtel for restaurering. Som mange vil huske, brant Norsk Kvernsteinsenter lokal marmor i en nybygd «middelalderovn» i Hyllestad sist juni, et prosjekt støttet av Riksantikvaren. Planen er å leske og teste brentkalken på flere restaureringsprosjekter i Norge, bl.a. på Selja klosterruiner og Stavanger domkirke. Siden jeg regelmessig jobber sammen med kollegaer i Stavanger, har vi nå gjort flere tester på domkirken med George Murphy og Bjørn Idland, som er restaureringsmurere ved Arkeologisk Museum (UiS). Det er ikke lett å leske kalk som er brent på tradisjonell måte. For det vil alltid være halvbrente og ubrente biter i slik kalk. Akkurat som i middelalderen. Vi lesket kalken på tre ulike måter, og det var liten tvil: tradisjonell hotmix ga det foreløpig beste resultatet! Continue reading

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Was Nidaros Cathedral built from stone extracted in a large underground Medieval quarry?

A carved-out, medieval soapstone block still attached to the bedrock. From excavations in the Bakkaunet quarry by Trondheim and Nidaros Cathedral, 2004. Photo by Per Storemyr

A carved-out, medieval soapstone block still attached to the bedrock. From excavations in the Bakkaunet quarry by Trondheim and Nidaros Cathedral, 2004. Photo by Per Storemyr

Ancient underground building stone quarries are rather common. They are known since at least the Old Kingdom in Egypt, some 6 500 years ago, when fine limestone was quarried underground close to Cairo (Tura) in order to provide casing stones to the Giza pyramids. But underground quarries are, interestingly, quite rare in the European Middle Ages. Apparently, there was no need to start difficult, large-scale underground operations to build churches, monasteries and cathedrals until the Late Middle Ages, when, for example, the underground limestone quarries in Paris and Caen in France started to become developed toward the gigantic network of tunnels and galleries we know today. Thus, it is remarkable that a large underground quarry may have been opened around AD 1200 in Trondheim, Norway, in order to provide soapstone for Nidaros Cathedral, the northernmost of Europe’s great medieval cathedrals. Why? Continue reading

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New open-access book: Soapstone in the North. Quarries, Products and People. 7000 BC – AD 1700

Several authors on excursion to the Hana soapstone quarry by Bergen during a book seminar in 2015. Photo by Per Storemyr

Several authors on excursion to the Hana soapstone quarry by Bergen during a book seminar in 2015. Photo by Per Storemyr

Together with lead editor, professor Gitte Hansen at the University of Bergen, I have co-edited a brand new book: On the archaeology, geoarchaeology and craft of quarrying and use of soapstone in the North Atlantic region. Without Gitte, this adventure would never have ended! The book contains 17 papers by soapstone enthusiasts and sums up a research revival that has been ongoing for the last 20 years. Norway is a main focus, where soapstone has been used from the Mesolithic until today, but the book also contains papers on Greenland and the North Atlantic Isles by Danish and British colleagues. It gives brand new insights into many aspects of soapstone, especially on sourcing artefacts by combined geochemical and archaeological methods. Continue reading

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“Nidaros: The Portland Cement Cathedral” (Baker Memorial Lecture)

The newly restored choir at Nidaros Cathedral in the 1880s (left) and 1994 (right), before the last restoration early 2000s. All the white calcite crusts are a result of leaching of calcium hydroxide from Portland Cement used in the 1880s. Photos by the Nidaros Restoration Workshop and Per Storemyr.

The medieval choir at Nidaros Cathedral just after reconstruction in the 1880s (left) and 1994 (right), before the last restoration in the early 2000s. All the white calcite crusts are a result of leaching of calcium hydroxide from Portland Cement used in the 1880s, and particularly during a restoration by 1920. Photos by the Nidaros Restoration Workshop and Per Storemyr.

This week I attended the international conference “Rediscovering Traditional Mortars” in Trondheim. The conference was hosted by the Nidaros Cathedral Workshop and it was part of the annual conferences organised by the British Building Limes Forum and its Nordic counterpart.

I was lucky to be invited to deliver two lectures, one on the experimental lime burning in Hyllestad earlier this year, and the Baker Memorial Lecture during the gala dinner. A very great honour to keep this traditional lecture for more than 230 delegates! I concentrated the lecture on the use of Portland Cement during the restoration of Nidaros Cathedral from 1869 on. Read on to get a glimpse of all the problems it has caused! Continue reading

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Forvitring av kleberstein på middelalderkirker – to videoer

Hvorfor forvitrer kleberstein? Foredrag om den gotiske vestportalen på Utstein kloster i 2017. Screenshot AM-UiS

Hvorfor forvitrer kleberstein? Foredrag om den gotiske vestportalen på Utstein kloster i 2017. Screenshot AM-UiS

Tidligere i år holdt jeg to foredrag om forvitring av kleberstein sett i lys av bygnings- og restaureringshistorie. Det dreide seg om portaler fra norsk middelalder og foredragene ble holdt på «Portalseminaret» i regi av «Domkirken 2025»; miljøet som nå restaurerer Stavanger domkirke og som jeg også er en liten del av. Alle foredragene fra seminaret (og mange andre interessante saker om restaureringen) er nå lagt ut på YouTube.

Kanskje kan mine to foredrag være til hjelp for folk som sliter med å forstå hvorfor kleberstein forvitrer. Veldig mye dreier seg om hva bygningene har vært utsatt for av forandringer og restaureringer gjennom tidene. Men noe av forvitringen kan også knyttes til steinkvalitet, tidligere luftforurensning og ikke minst vann! Rett og slett lekkasjer! Innholdet i foredragene er i stor grad basert på min gamle doktoravhandling The Stones of Nidaros fra 1997 og mange artikler om forvitringshistorie, bl.a. Weathering of soapstone in a historical perspective. SE VIDEOER!

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Experimental archaeology: Building a “classic”, intermittent limekiln and burning marble at Millstone Park, Hyllestad, Western Norway

The freshly built, classic limekiln at Hyllestad in operation, june 2017.

The freshly built, classic limekiln at Hyllestad. In operation, June 2017.

It took us about six months: Building a cylindrical, intermittent limekiln of the classic Roman/Medieval type with local materials only – stone rubble and clay. In June this year (2017), we built the firing chamber, filled the kiln with 2.5 tons of local marble and started burning. A week, night and day, with much of the local community involved! Here’s an extended photo story of the project – the first of its kind in Norway. Media was interested! A national radio story here, a local newspaper story here (in Norwegian).

The quicklime (burnt marble) will be tested at Selja medieval monastery and other restoration projects in Norway. Big thanks to all, 30-40 volunteers and paid people (see list at the end) and support from The ruin restoration programme of the Norwegian Directorate for Cultural Heritage, as well as Hyllestad Municipality! The project was carried out by The Norwegian Millstone Centre/The Museums in Sogn og Fjordane County. Continue reading

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Update after long absence – follow on facebook

Over the last six months I’ve been immersed in practical and scientific works and so I’ve been unable to write sensible blog posts on this website. I guess most bloggers experience something similar once in a while. If you want to get an idea of what I’ve been up to, please follow me on my personal facebook profile. There you can find brief news about e.g. building and running a “medieval” limekiln at Hyllestad in Western Norway, and various projects across Norway; from rock art in Finnmark county up north to stone conservation at Stavanger cathedral in the south.

Now I’m on a combined study tour and holiday in Ireland and Northern Ireland, focusing on geoparks and heritage, and having just visited Giants Causeway:

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Happy New Year from the most beautiful old quarry in Western Norway!

A medieval millstone quarry taken over by a creek in rainy Western Norway: At Hyllestad, the largest Viking Age and Medieval quarry landscape in Northern Europe. Photo by Per Storemyr

A medieval millstone quarry taken over by a creek in rainy Western Norway: At Hyllestad, within the largest Viking Age and Medieval quarry landscape in Northern Europe. Photo by Per Storemyr

With a picture, taken today, of a splendid little old quarry in Western Norway, I wish all my clients, partners, colleagues – and those who read my blog and website – a Happy New Year! Continue reading

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Geoarchaeology of the famous ancient amethyst mines in Wadi el-Hudi, Egypt: Desert heritage at risk

A fading raw amethyst from Wadi el-Hudi, Egypt. The purple variety of quartz. Photo by Per Storemyr

A fading raw amethyst from Wadi el-Hudi, Egypt. The purple variety of quartz. Photo by Per Storemyr

This fall I joined the Wadi el-Hudi expedition to the famous Middle Kingdom amethyst gemstone mines in the Eastern Desert south-east of Aswan. The expedition is led by Dr. Kate Liszka of California State University San Bernardino (US), and over the last few seasons it has excavated and documented the ancient mining settlements in very high detail. My task was to take a closer look at the geoarchaeology – to try and understand relationships between geology and mining. It is hugely important to document what is left, for the ancient mining area is now at high risk from looting, modern gold mining and stone quarrying. Continue reading

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Værnes: Norges mest komplette sandsteinskirke fra middelalderen

Sørportalen på Værnes kirke da pussen på kirken var hogd vekk på 1990-tallet. Her er det sandstein i murene! Og grønnskifer i portalen. Foto: Per Storemyr

Sørportalen på Værnes kirke da pussen var hogd vekk på 1990-tallet. Her er det sandstein i murene! Og klorittskifer i portalen… Foto: Per Storemyr

Den er dekorert med elementer av kleberstein og klorittskifer, men ellers er det sandstein så langt øyet kan se: Værnes er Norges mest komplette sandsteinskirke fra middelalderen! Den rager i størrelse og volum av brukt sandstein langt over middelalderbyggverk i tilsvarende stein i andre deler av landet! Her er et sammendrag av min artikkel til boken «Værnes kirke – en kulturskatt i stein og tre» som ble utgitt for et par uker siden (november 2016). Det er Grubleseminaret som står bak, med Morten Stige og Kjell Erik Pettersson som fantastiske redaktører av boken! Continue reading

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