When Sea Stallion puts to sea bound for Dublin in 2007 an impressing sight will stretch towards the sky; 112 square meters of sail in red and yellow stripes.
'We have no clue about how the Vikings dyed their sails then, but from descriptions in the sagas, from ships images on the Bayeux tapestry and in chalk paintings in churches we do know that the sails could have coloured stripes. Sea Stallion's sail shall be red and yellow. This has been the intention all the time but the sail had to be used for some years first to make the fabric's surface more absorbent,' tells boat builder Vibeke Bischoff from the Viking Ship Museum.
Coloured sails are pretty, but the colour is more than just aesthetics: ochre is a natural protection against rot and mildew.
Venecian tradition
'Sea Stallion has a big sail. Therefore it is important not to choose a method that makes the sail more stiff or heavier. Here in the North we have been tanning our sails for centuries, but this requires to lower the whole sail in the liquid. Another known Nordic method is to mix ochre with for instance fat, but this would make Sea Stallion's sail far too heavy and it usually works better with woollen sails,' explains Vibeke Bischoff.
Therefore she went to Venice where there is a long tradition of colouring sails with ochre. In Venice it has been the usual thing for a long time that every family painted its own pattern in the sail to be able to recognize the boat from a long distance.
'The method they use is to mix ochre with sea water and afterwards to smear the solution with a sponge on the sail. The salt in the sea water fixes the colour and when the sail is dry it is put into the sea and rinsed so the surplus colour can be washed out. This method is so simple that it would be really good if we could use it.'
Convincing test
Vibeke Bischoff took some samples of the same fabric as Sea Stallion's sail to Venice. 'I got help from Gilberto Penzo who works with ship reconstructions and who writes books about historic ships. The sails I got to see there were all coloured with red and yellow ochre and no colour came off them at all. The sails were made of cotton whereas Sea Stallion's sail is of linen. We do not know for sure whether that makes a difference. But we did a test with our sail fabric and the result was very convincing,' says Vibeke Bischoff and continues:
'The colours do not run into each other, because it is pure pigment in water. Pigment stays where it's put. It is only the water that runs further into the fabric. In other words it should be rather easy to control the stripes and it looks fantastic.'
Enough salt?
The sail fabric was brought back to Denmark where it will hang outside in rain and storm for the whole winter. There are more test in progress.
'I want to do four tests. One with sea water from the North Sea, from the Kattegat, from the Roskilde Fjord and one with a high concentration of sea salt corresponding to the salinity in the Mediterranean. Because I do not know whether the Danish sea water has enough salt. Neither do I know how we are supposed to get the sail into the sea and get it rinsed, and where we can do that, but we will find out,' says Vibeke Bischoff and concludes with a smile:
'I am convinced that the method from Venice is the right way to colour Sea Stallion's sail. But the best is perhaps to let the midship crew do the colouring cos if the work isn't done properly it is them the paint will drip onto!'