Tanning Jantje’s linen sail the traditional way – Hermann Ostermann explains

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Tanning Jantje's sail with cutch

Tanning Jantje's sail with cutch Tanning Jantje's sail with cutch

Paying the tanning mixture into Jantje’s sail; the sail before tanning; heating the tanning mixture. Click on the images for a larger photo

In weblogging, one good thing often leads to another. Earlier posts about the restoration of a steilsteven tjalk named Jantje explained that she still had an old sail in good condition when she was acquired and that expert Hermann Osterman had tanned the sail using the old methods – and naturally a number of readers asked for more information.

I’m delighted that Hermann has kindly sent us the photos above, and the description that follows. In fact, I’m pretty sure various tanning methods have been used over the centuries and these days I gather the favoured product is standard wood preserving stains such as Cuprinol – but Hermann used the traditional cutch – in this case tannin-laden extracts from the South American quebracho tree (see definition 1, definition 2).

Here’s what Hermann has to say:

‘The tanning of a traditional sail cannot be performed in a boatshed: you need a flat, clean cement floor, or better, short-cut grass, and also a copper of about 80 litres capacity with a fire chest. In the days of fishing under sail nearly every fishing community had a tan house or a such like arrangement.

‘I have written a detailed account on the common methods, recipes and materials used for preserving nets and sails that appeared in  the journal Maritime South West, which is published by the South West Maritime History Society. The journal for 2009 is available at a cost of £12, plus postage from society member David Clement, who can be emailed at dclement1@toucansurf.com.

‘Jantje’s sail had been stored with other equipment in her hold for many years, and I must say it represented a rare opportunity to tan the sail, which was an example of the old craftsmanship. Indeed, one should seriously consider whether it is right to tan an old sail, for it should only be done if it is in such good condition that it will be possible bend it on for sailing once again, and if you have reason to expect it will benefit from the treatment as well as taking on the traditional colour of a tanned sail.

‘In fact, Jantje’s sail had been made from linen cloth in the 1920s or ’30s had been left untreated and had become greyish colour, in overall it was good enough for further use as a sail.

Based on my own experience of sail tanning, I chose a solution consisting of about 1.5kg of quebracho powder to 10 litres of water, which was simmered for a little over two hours to extract the tannins (that’s the minimum; longer is even better). The temperature should be maintained at just up over 70degC; it is important not to overheat the liquor. Some 10g of soda is added after two hours.

Before treating the sail, I wetted it with water. This has to be rainwater, or water from a well, river or sea-water. The whole procedure, with wetting and dressing the other side of the sail took at last about 8 hours.

Usually one cannot expect to achieve a good deep colour from a first tanning treatment – the colour seen in old sails is the result of repeated dressings, but Jantje’s sail took on a particularly good rich shade.

‘Before tanning a sail it’s important to test the process on small patches of canvas, and to record the steps, quantities and timings of the procedure, and to choose the tanning mixture and treatment in line with local traditions.

‘Nowadays cutch is supplied in square, round, and irregular pieces, which may be pale red, pale brown, or nearly black, and often having a sweetish after-taste, and is also available as a highly soluble dyeing powder. The quebracho powder (trade mark Unitan) I used for Jantje’s sail, is extracted from the hardwood of the South American trees of the same name and is available in a range of different readily mixed colours.

‘Some alternatives for making cutch include oak and birchbark extracts, natural ochre powder and certain fatty liquors used in the leather industry.

‘Hermann Ostermann’

Thanks very much Hermann – that’s tremendous!

Tanning Jantje's sail with cutch

Tanhouse at the Fisheriesmuseum of Oostduinkerke

Tanhouse in the Fisheriesmuseum of Oostduinkerke

Tanhouse in the Fisheriesmuseum of Oostduinkerke


Tjalk Jantje is back on the water and will soon have a new cotton rig

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tjalk, dutch barge, sailing boat, holland, nordhorn, jantje

tjalk, dutch barge, sailing boat, holland, nordhorn, jantje tjalk, dutch barge, sailing boat, holland, nordhorn, jantje

tjalk, dutch barge, sailing boat, holland, nordhorn, jantje

Tjalk Jantje now, before she was restored, the celebration, and her sail arranged for tanning – and the pot used in tanning

In Nordhorn in Germany near the border with Holland, poor Hans-Christian Rieck has broken his foot working on his organisation’s tjalk named Jantje. Having broken my own ankle last year he has my heartfelt sympathy, and I can only hope his recovery is rather better than mine has been.

A small consolation is that he’s at last had time to tell us about the boat. Here’s what he has to say about Jantje:

Jantje is one of the Dutch Tjalks, in this case of a subtype called Steilsteven – it’s equivalent in England would be the Thames barge.

‘She was built in 1923 at Delftzijl on the Dutch side of the River Ems estuary and worked the Frisian Lakes until the 1960s, when she was laid up, being to small and to slow to be competitive. Sadly neglected, she spent 30 or so years on a mooring at Makkum on the Ijsselmmer.

‘Fortunately, some businessmen of our town Nordhorn came upon the idea to aquire a historic ship as a reminder of the glorious maritime past of our city, and when the treasurer of our association and myself were asked to find a suitable craft, we found Jantje.

‘She was bought, sandblasted, sprayed and then fitted out with an advanced system of ballast tanks to enable her to enter the city, as in recent times our city fathers have built bridges with very limited headroom over our canals and rivers.

‘The ship now floats at a jetty by the old town port and will frequently leave her mooring for special maritime events in our area.

‘I’ve added some photos of the renewed boat’s christening – the guy with the crutches is me by the way!

‘We have tanned Jantje’s sails the traditional way with the help of Hermann Ostermann, whom you may have heard of, one of the last guys to knows how to tan a cotton sail the proper way. We hope to have the traditional rig ready by next spring, so we can have a test sail on Lake Vechte at the next canal festival.’

Many thanks Hans-Christian! I look forward to hearing more in the not too distant future.

Traditional steel Dutch dinghy and Forest & Stream skiff compared

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pam w skiff

pram w skiff halftotal Pram dingi w Cadeau and Seneca BILD0318

Dutch dinghy and steel-built Forest & Stream skiff

Over in Holland, Hans-Christian Rieck has taken these photos of a traditional steel-built Dutch dinghy of a type often used as tenders to steel-built barges and other craft. They’re strikingly curvaceous little boats, given that they’re made from plates of sheet steel, particularly when compared with the steel-built Forest & Stream skiff seen in the background.

The F&S skiff is being smoothed with filler prior to being painted and having its woodwork fitted. I will be fascinated to hear how this boat works – and I trust it does work well in steel, as it will presumably have a theoretical life time of 80 years or more. I’m pretty sure it will be fine, by the way – it’s clearly greatly scaled up from the 12ft ply dink I drew some ten years ago no, and that will no doubt compensate for the extra weight of the hull. I’d like to take a trip to see it once she’s in the water if that’s ok please Hans-Christian!

Hans-Christian’s workshop trains youngsters in the metalworking skills, and the steel dinghy belongs to the Graf Ship Association – it is destined to be cleaned and refinished.

Here are some earlier images of the F&S skiff, and of a ship, the Jantje ready to be transported to Nordhorn after being sandblasted and sprayed.

skiff starboard2 Skiff total forward buoyancy2