Tar

cliffordpope

cliffordpope

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Traditional boats, especially working ones, have "tarred" bottoms. What exactly is tar, and where would I get it? Is it that lovely thick bitumous paint sold in ironmongers, or the lumps of black pitch that roadmenders melt over gas rings, painted on with a long-handled brush while still boiling hot?
My boat has about 100 years of some black substance underwater, and I'd like to renew it in the traditional way.
 
Really .... everyone to their own, I guess! I imagine that a Victorian yachtsman would see the advantages of today's underwater primers and antifouling paints over the black varnish that they used, which wasn't particularly effective.
 
Tar was a by-product of the coal gas industry and was liberally used for all kinds of purposes including painting the outside of level crossing keepers cottages - no doubt would be banned nowadays by the EU. - SBO
 
Ah, the dear old Victorian yachtsman! Like the east coast salt of old, they return from history and taunt us for our sentimental ways. "I'd have loved satnav in my day", they say, "I can't believe you still use sextant!" The Victorian yachtsman would probably do away with sails altogether and buy a motor boat. The east coast fisherman would be saving up for a factory trawler to destroy the bottom of the sea with. Ignore these unpleasant fictional thugs of history! There would be no classic scene at all if we heeded their ghostly voices.
 
Thanks! Yes, I see your point, but I have read that once a boat has been tarred, it's impossible ever to paint it because the paint won't stick. The underwater planks are saturated with an oozy black substance. A certain amount will scrape off, but a blowlamp just brings up more to the surface.
 
There are three distinctly different substances which are referred to as "tar". One is Pine or Stockholm Tar, derived form distillation of pine timber or foliage. Another is bitumen, which is a fraction of crude oil. The third is Coal Tar, a residue left after coal was distilled to form Town Gas and coke. Because of their different origins, they are quite different in properties. Coal Tar is no longer available because natural gas has taken over from the local gasworks.
As a near approximation, you could try a road asphalting company to see if they will sell you a gallon or two of bituminous emulsion. This is used to "glue" asphalt to the underlying gravel of a roadbed. It is quite runny, and a very dark brown colour, almost black. You can paint it on with an old brush [I wouldn't use a new one with this stuff, 'cos you'll throw it away afterward] and wait for the emulsion to "crack". The water fraction will evaporate, leaving a thin film of bitumen. The natural solvent for this stuff is mineral turpentine [not to save the brush, but to get it off you and your clothes before 'er indoors sees them.]
Peter.
 
Many thanks, Peter. you have answered my next question too (What is Stockholm Tar?).
So basically something bituminousy would be the "modern" substitute for good old coal tar. I suspect that is, latterly at least, what the hull has had on it.
Years ago on the Broads I remember someone painting the underneath of his yacht with boiling "tar". He tipped large lumps of black substance (pitch?) into an oil drum and melted it, and then brushed it on quickly before it set again. He said it was the cheap traditional way before antifouling came in, and also had the advantage of sealing small cracks, especially those that had opened up during the winter season ashore.
But using something naturally liquid sounds easier.
 
I recall seeing a documentary on rebuilding/maintaining narrow boats. They were coated with pitch (hard and brittle) which was made plastic by the addition of some coal tar (always runny) when being melted. Perhaps enquirys of the narrow boat enthusiasts would yield info about equivalents or sources.
 
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