Smart conservation

As another productive and fun day of cleaning the cog with dear colleagues from the Estonian Maritime Museum draws towards the evening bit, it’s a good moment to reflect a bit this adventure of ours called conservation of the Tallinn cog.

Yes, this is the very well-preserved early 14th century wreck of a cog-ship, that legendary carrier of the Hanseatic merchants, about which we’ve been raving about in this blog since the start of the year (please go back to the older posting to learn about the whole thing). And yes, our bit is to plan and manage conservation of this absolutely amazing find unearthed in 2015 on dry land amidst building construction work in Tallinn’s Kadriog Park. How to preserve such a unique and complex artefact of some 18 meters of length, which is set to be put on display in the Old Town premises of the Estonian Maritime Museum in late 2019? That’s the question we were posed with, us being not only the FOG guys, founders of the company For Our Generation, but also specialists in conservation of shipwrecks, which in turn is the very reason we ever got the gig and ended up establishing FOG.

The thing I want to reflect now is our bold decision of not introducing any stabilization agents to the wood material. (For many a reader, this might drift too much towards the fine art of conservation, but please bear with me…) I mean, we, as somebody with rare training and good experience in dealing with such difficult finds, were asked to do the conservation plan, and we ended up not to suggesting the standard stabilization method of shipwrecks we conservators normally do to shipwreck-wood! I’m referring to impregnating wood with Polyethylene Glykol (PEG) or some other stabilization agent, the function of which would be to give physical support to wood cells weakened due to decomposition in waterlogged conditions. This is what’s been done to the Vasa in Stockholm, the Bremen Cog in Bremerhaven and numerous smaller marine archaeological finds worldwide, with great results.

How come we decided not to do it but let it air-dry very slowly? Of course, I must add now that it’s really not like we’re doing NOTHING, as there’s a whole lot of other conservation actions, such as extensive cleaning (very laborious!) and strengthening the fragile whole with new pegs (very difficult!), we must deal with before the wreck can be put on display, but let’s stick for now with the stabilization bit. Is it stable? Will it be stable? How did we know to start with that no extra stabilization chemicals were needed? I mean it was a bit of a bold choice not to spray it with something, as was done with the Vasa, or take it apart and impregnate separate pieces thoroughly, and I must confess that we’ve deliberated about this a lot and occasionally I have nightmares of one day taking the ferry to Tallinn and meeting the wreck in ruins because of our decision of not using extra chemicals.

Well, so far so good, everything looks good now. Yes, there are cracks, but they’re the kind you really cannot avoid, this being natural wood, which still reacts to humidity as any wood would, and yes the upper planks show fantastically the effect of too fast drying, most likely already upon excavation back in 2015. But all in all, the whole thing is drying nicely, just as we predicted.

Our prediction was based first of all on the very good condition of the oak-wood, which was verified of course by our close examination of the wreck but also by material-analysis data. Therefore, based on our experience with marine archaeological wood, we predicted that the wreck will withstand controlled slow drying without dramatic dimensional changes. Another cornerstone of our decision-making was the dryish state of the wreck at the start of our involvement. The cog wasn’t waterlogged. Hadn’t been for a good while, as she was initially excavated from a terrestrial site and had already spent a couple of years in a tent after the excavation. Because of this, we ruled out the PEG-method so often used with shipwreck wood, which would have required returning the wood to waterlogged state. This would have resulted in damages, we thought, not to mention how laborious and slow it would have been to immerse the whole thing or take it apart… Not possible in the given time-frame, nor wise, as less was enough in our opinion.

Conservation is not about fancy treatments done with special chemicals after very scientific analyses. It’s about understanding the object at hand and doing only what’s needed to preserve the tangible thing while enhancing the intangible. By the latter, I refer to the wealth of significances historical objects possess. Why are we preserving this and how are we telling its stories?

Another thing of great importance conservation-wise is our very attitude. We’re treating the cog as a ship she once was and still is, not as some abstract construction of materials, meaning for instance that when fastening the planks in place we use caulking material and wooden pegs traditionally used in shipbuilding (please look closely the pictures in this posting!). We try to understand the ship rather than rely on scientific analyses or synthetic materials often preferred in conservation of museum objects.

Sometimes very drastic and incredibly slow conservation processes are needed. I have nothing against advanced scientific analyses and methods, which truly help a lot (we’ve utilised them here as well!), but I think here we have a fine example of the ideals of conservation: minimum intervention.

Eero Ehanti