One among my best skilled fears is {that a} piece I’ve labored on—weeks, months, or years later—immediately begins to interrupt down, discolor, or collapse due to one thing I did. I’ve genuinely woken up within the evening enthusiastic about a remedy I did on an object years in the past and nervous that one way or the other some unseen side of that remedy is now doing one thing sudden and terrible.
At school we discovered about a number of examples of issues carried out to furnishings (typically the issues touted on-line as fast ideas) that brought on harm both instantly or slowly over time (screws in joints, inappropriate glues, oil revivers, and many others). As a restorer, I typically curse earlier repairers who’ve made my job now even more durable than it must be.
However we shouldn’t focus on this stuff to make folks really feel unhealthy; finding out them may help us be taught what to keep away from and the right way to make tough selections after we don’t essentially know all of the dangers.
So within the spirit of that, let’s discuss in regards to the Oseberg Sleds, 1200-year-old Viking items which have disintegrated internally and was, primarily, wooden mud held within the form of sleds solely by their varnish.
The Oseberg Viking Ship
Final yr, on the Museum of the Viking Age in Oslo as a part of the ICCROM Course in Wooden Conservation Expertise, I used to be in a position to get a detailed have a look at these extraordinarily fragile picket objects. The Oseberg Viking Ship itself is beautiful in how largely full it’s and the way seaworthy it feels for a chunk dated to round 820 AD. The Oseberg Sleds are distinctive and ornately carved. They have been uncovered round 1905 together with the ship on a farm close to Tønsberg, Norway.
Whereas the ship is in unimaginable situation, the sleds have been described as “not likely wooden anymore and [with a] power similar to that of crispbread.”1 Once we have been allowed to get in the identical room as them, we have been urged to be very cautious as a result of any heavy step or vibration may trigger harm, and I keep in mind being very nervous that they may simply crumble earlier than my eyes.
So how did this occur? By a preservation remedy carried out on them over 100 years in the past, sulphuric acid has been slowly disintegrating the timber from the within.
I spoke with conservator Susan Braovac, who has labored with and researched these objects for years, to grasp higher what occurred to them, why this remedy was carried out, and what the selections are we make now that might probably have the identical dangers.
Historical past of the Oseberg Sleds
It’s believed that again within the ninth century the ship and its contents have been ceremoniously buried as a part of a funerary custom for a girl of notably excessive standing. The our bodies of two older ladies have been discovered aboard the ship amongst what was presumably a set of their possessions, though actual particulars are unknown. The mound they have been buried in contained a large amount of clay, which primarily prevented air from attending to the ship, preserving it from each drying out and from being too eaten by fungi. The ship, the our bodies, and all the opposite objects aboard have been protected against daylight, bodily harm, and decay for hundreds of years on this situation. The picket objects, nevertheless, sat fully soaked for a very long time, and whereas oxygen and fungi couldn’t get at them, some micro organism have been in a position to slowly assault the timber.
The result’s similar to that of any shipwreck dredged from beneath the ocean. Pulling a ship out of the ocean signifies that it immediately has to face the environment, and plenty of picket objects which are pulled out of the ocean or floor after such a very long time can generally dry a lot too shortly, inflicting them to fully deteriorate.
Not solely do you will have the traditional dangers of wooden drying too shortly (checking, splits, and many others.), however as a result of the lignin and cellulose chains that the wooden is created from have been deteriorated by bacterial infestation over time, the shear act of liquid water leaving a hole cell may cause sufficient capillary or vacuum strain to fully collapse that cell. Susan informed me to think about sucking the air out of a straw, or maybe an empty water bottle, and watching it compress.
She confirmed us a time lapse of a chunk of archaeological waterlogged timber left to dry. The place you may anticipate possibly 5% to 10% shrinkage in regular timber drying, this piece appeared prefer it shrank by 60% tangentially. It was like watching a sponge in a vacuum press.
Some timbers (e.g., oak) which are extra immune to bacterial degradation nonetheless keep sufficient stability as to if this drying course of, however for others it’s an actual problem to protect them with out critical deformation.
Treating the archaeological waterlogged timbers
The ship physique itself wasn’t as deteriorated by the burial setting, and it was in a position to be dried slowly within the air with little or no consequence.
However for the sleds, and plenty of different picket objects discovered, there was a real danger that letting them dry would result in their destruction. So both it’s a must to shove them again in water (extra on that later), or it’s a must to do one thing else to them to take away the water in a manner that doesn’t trigger vacuum-like mobile collapse, and/or substitute the water with some stable materials that may assist maintain it in place.
The oldsters who excavated these sleds knew there have been dangers, they usually spent a while exploring choices for the right way to deal with them. Susan defined how they spoke to plenty of different professionals within the discipline, and even traveled right down to Denmark to be taught extra of how folks have been dealing with this problem. The reply was an alum remedy first revealed in 1861.
Alums are water-soluble aluminum salts. Like every salt, they dissolve in water, after which when the water evaporates, they’re left behind of their crystalline kind. So the idea is (crudely) that when you soak the waterlogged timber in a shower of alum answer, the alum will penetrate the wooden, displacing water. Then if you take away all of the remaining water, the alum salts will probably be left behind within the gaps to structurally assist the wooden and stop it from collapsing.
The remedy was used considerably generally in Europe and different locations by way of the mid-1900s when newer therapies have been being developed, and it began to turn into obvious that one thing wasn’t proper. Lots of the alum-treated items, it appeared, have been turning to mud, or in any other case turning into extra fragile over time.
What went fallacious
What I need to emphasize right here (and Susan was additionally very clear about this) is that this remedy wasn’t half-assed. This wasn’t some “Properly, let’s simply give this a try to see what occurs” strategy. This was finest follow on the time. Some items had been handled with alum many years previous to the Oseberg excavation, they usually have been nonetheless wanting fairly good in 1905 by many accounts.
It’s solely with latest evaluation, and the work of Susan and others, that we even perceive now what went fallacious. Thanks largely to her and her colleagues’ efforts, we do have an excellent concept for that: In an effort to assist the alum dissolve fully and penetrate the wooden as deeply and fully as potential (though evaluation exhibits the remedy didn’t fully penetrate the timber), it was heated to 194°F (90°C). You understand how I stated that alum is an aluminum salt? Properly, the non-aluminum elements are sulphates, and when the alum is heated and utilized to the wooden, the salt breaks down in such a manner that creates sulphuric acid.
The would-be preservationists have been unknowingly filling the timber with a mix of aluminum, alum salt, and sulphuric acid. The remedy appeared prefer it labored completely, however over time that sulphuric acid was slowly destroying the timber inside, chewing by way of the very materials that wooden is manufactured from and turning it to mud.2
After the alum remedy, the objects have been coated with linseed oil and a varnish that Susan didn’t know the precise particulars of. A long time later they have been coated with a contemporary materials, and now these floor coatings are the one purpose the sleds are nonetheless formed like sleds in any respect (with assist from trendy helps).
Skilled confidence and danger
It will be really easy to only assume, “These of us have been idiots and didn’t know what they have been doing, however we do now.” That, nevertheless, can be unfair. Whereas the science on the time wasn’t what it’s now, the practitioners themselves did about pretty much as good a job as you may need been in a position to do. They frolicked pondering and discussing. They researched the choices and spoke with different professionals. They reviewed objects that had been handled with totally different strategies to see what had labored. Susan and I agreed that that they had principally carried out the perfect factor based mostly on what was recognized and what their purpose was. This was, by all understanding on the time, a wonderfully good remedy for these objects.
This implies a risk whereby I might undergo comparable lengths to decide on an excellent remedy, solely to have folks 50 years from now discover out that that remedy has brought on unexpected issues. As I be taught extra in regards to the methods issues can go fallacious, I’ve discovered my confidence in my work lower. “Who’s to say?” is never a reassuring assertion when shoppers ask in regards to the longevity of your work.
If the Dunning-Kruger impact, it’s in the end a illustration of this: That confidence spikes early, after which decreases shortly with data.
You’ll have skilled an identical scenario yourselves. I believe Ben Strano stated it nicely on Store Discuss Dwell, once they had Randy Wilkinson on speaking about wooden identification. The extra he discovered in regards to the anatomy of various woods, the extra he realized which you can’t actually be as assured about what a wooden is as some folks appear to be. Be cautious of the people who find themselves actually assured on that Fb group that the wooden you will have is northeastern Mexican hibiscus or no matter.
I do assume so much today in regards to the dissonance between having to pay attention to (and anxious about) all of the methods issues can go fallacious, the actions I would take that might make issues worse, after which needing nonetheless to maneuver ahead as finest I can. My consumer wants me to seek out them an answer, and I can’t simply inform them to attend till we have now higher solutions.
Until, possibly, I can.
The carving in a water tank
It seems that though preservationists put a number of work into the choice, they weren’t fully impressed in 1905 with the alum remedy. There was concern about how the main points of a number of the finer carvings have been being misplaced. And so, with six notably ornately carved items of timber, they really determined to only stick them again in some water till a greater answer could possibly be discovered.
Susan informed me about this one carved animal head pillar that was saved in a tank of water for roughly 50 years, surviving two world wars, and we each admired the decision-making concerned.
They accepted that they didn’t have the expertise on the time to do the piece justice, and they also put it in an aquarium and monitored it rigorously for many years.
Finally, on account of strain from Nazi occupation, in addition to the event of freeze-drying expertise, conservator and chemist Annemor Rosenqist and Brorson Cristenson developed a brand new option to deal with the item and keep its element. (You’ll be able to see the ultimate outcome and the element maintained within the cowl picture for this publish.) I’ll go away the specifics of this remedy for an additional time, however Susan and I have been each fascinated and impressed by these decisions: each the boldness to resolve to place the piece in a tank of water till some unknown future remedy, and the boldness to take away it and try a brand new remedy when the time got here.
I believe for me there’s a worry of suggesting that maybe we don’t have the capability now to do what’s finest—that we’ll be seen as unprofessional or incompetent. It’s nice to see an instance the place that call was made with confidence and proved to be the precise one.
Whether or not you do nothing or one thing, nevertheless, it’s nonetheless a choice.
The workmanship of danger
I take consolation in David Pye’s description of craft as a workmanship of danger. That handcrafted work, by its very nature, entails not partaking with pre-set machines that may produce repeated outcomes (theoretically), however accepting the danger of a practiced hand. Taking a carving chisel or a brush of varnish to a ready picket floor comes with the potential that you simply may slip and make an error.
If potential, we are able to follow. If you wish to play Beethoven in your piano, you begin by practising your scales after which by practising the piece. You’ll be able to put together your self till the repetition is so constant that the danger of failure is low. As a lot as you follow, nevertheless, finally it’s a must to carry out, and on the day of your efficiency, a part of what makes it unimaginable is figuring out how potential it nonetheless is for errors to be made.
Restoration and conservation have this danger as nicely (nevertheless, only a few crowds are exhilarated by it). An individual seemingly solely has one or two rocking chairs at most that used to belong to their grandparents and that maintain with them precious private recollections. The issues these particular chairs face are sometimes distinctive to them, and the sentimentality is irreplaceable.
There are solely three roughly 1200-year-old Norwegian Viking sleds on this planet that I’m conscious of. Our capability to follow therapies on them and hope for the perfect may be very low.
Susan was very grateful that testing will be carried out on a number of the much less vital archaeological timber items as a way to be taught extra about what occurred and what will be carried out. Nonetheless, when the time comes, she stated there are nonetheless a number of unknowns. She recalled being amongst a staff of knowledgeable conservators and chemists, and none of them—regardless of their finest testing and assessments—could possibly be sure about what precisely would occur in the event that they tried various things.
Making decisions
The data of what can go fallacious can (and doubtless ought to) destroy some confidence, particularly overconfidence. I reckon we ought to be not less than considerably cautious of inflicting hurt or reckless harm, and that’s not simply my power nervousness talking. However determining the right way to regain confidence in shifting ahead is the subsequent step after that, I believe. How lengthy do I spend worrying about what I don’t know that I don’t know?
Dunning-Kruger could outline the insecurity that’s skilled as soon as we be taught extra a few discipline like woodworking, however there’s a step after that that entails constructing the boldness to maintain shifting ahead after we know that we don’t know all the things.
Susan and I mentioned this query. In conservation, it’s good to assess the recognized dangers; it’s good to try to perceive what can go fallacious and what may not. Typically it seems like whereas there could also be many “fallacious” decisions, there are by no means “proper” decisions, solely “justifiable” ones.
When we have now these sorts of conversations collectively, sharing what has gone fallacious and what has gone nicely, we are able to discover higher options collectively.
It’s one of many causes there are specific codes of follow or skilled requirements elsewhere. Supplied these codes and requirements are developed in good religion with a variety of individuals, getting of us collectively to debate the right way to finest deal with these items and never make the identical errors once more, or not less than scale back them, will be considered one of our best instruments. Right here in Australia we have now the Burra Constitution, which offers steering on the right way to strategy issues and emphasizes the significance of session all through the method of working with any culturally vital place or piece.
Historic England has been partaking in the previous few years on session to design higher requirements for dealing with waterlogged timber particularly. That stated, it’s price noting that one commonplace strategy is just not essentially proper all over the place and for everybody.
One form of danger evaluation that Susan talked about was when her staff was deciding how and when to deal with the opposite broken artifacts of their collections. They needed to assess how for much longer each bit would final in the event that they did nothing. They needed to quantify how for much longer every merchandise had—what number of extra years it could realistically survive.
If the item’s timeline was quick—if the danger of doing nothing meant virtually sure destruction—then even when they weren’t one hundred pc assured with the remedy, they have been extra seemingly to present it a attempt. Even with these matrices and requirements to face behind, the ultimate resolution and follow-through aren’t assured.
At Studio Conservation, the place I work now, we regularly joke that the time we spend standing round stroking our chins and having a chat in regards to the object we have to work on is a few of our most essential work. Ideally, we’d like to essentially perceive what’s vital in regards to the piece and what issues and dangers are concerned within the job. Checks may have to be carried out, each to be taught extra about what we’re engaged on and what affect remedy may need. For instance, simply cleansing one thing can imply we unintentionally wash away one thing essential if we aren’t cautious (a historic dye, a maker’s signature, an imbedded stain the place somebody’s grandmother’s hand had rested on the arm of a chair, and many others). Quite a lot of cleansing options could also be examined in small portions to ensure they received’t unintentionally take away greater than we would like them to. In the end, we need to be sure that the alternatives we make are proper for the item, in addition to the folks for whom the item is critical.
When somebody asks me, “How would you take care of this?” typically my reply is one thing akin to “I don’t know but.” We will solely hope that our shoppers perceive this isn’t incompetence however care.
The place they’re now
The Oseberg Sleds have only in the near past been moved. A new wing of the Museum of the Viking Age has been constructed, and most of the ships, in addition to a number of artifacts together with the sleds, are shifting with them.
The sleds themselves will seemingly be moved within the coming spring. Once we have been there, the sleds had already been moved into a short lived room to guard them. A particular monitor had been constructed, they usually have been being moved alongside it at a tempo of inches a day due to how fragile they’ve turn into.
Giant metal beam stillages had been constructed across the numerous Viking ships themselves in order that they could possibly be hoisted on overhead cranes into their new positions within the enlargement of the museum. Though the staff has been calculating out and engineering a design that ought to flex one thing like lower than 8mm throughout its complete size (the trouble to review and perceive the structural deformation of the ships is an entire dialogue to itself), what finally ends up taking place will solely be revealed as soon as the issues themselves are moved in actual life.
You’ll be able to watch a time lapse video of the Oseberg Ship being moved right here.
If you happen to get the prospect to go to this museum in Norway when it reopens, I extremely suggest it. Go try these sleds if they’re on show, and know that whereas they may look static of their present scenario, an excessive amount of thought, care, and disaster have gone into what they’re in the present day.
1Braovac, S., McQueen, C.M.A., Sahlstedt, M. et al. Navigating conservation methods: linking materials analysis on alum-treated wooden from the Oseberg assortment to conservation selections. Herit Sci 6, 77 (2018). https://doi.org/10.1186/s40494-018-0241-y.
2Braovac and Kutzke. The Presence of Sulfuric Acid in Alum-Conserved Wooden – Origin and Penalties. Journal of Cultural Materials 13S (2012).
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