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Color of bottom plates on the Cutty Sark

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  • Member since
    March 2003
  • From: Illinois
Posted by wjbwjb29 on Monday, August 3, 2009 9:14 AM

I didnt look at the other pics. That is very funny though.

 

Bill

On the Bench:   Trumperter Tsesarevich on deck Glencoe USS Oregon

  • Member since
    January 2006
Posted by EPinniger on Sunday, August 2, 2009 2:16 PM

Looking at the model on the link you posted, it looks to me that the "plates" are actually made of pale varnished wood, not metal. This sort of thing is very common with ready-built "decorative" models like this, which are really intended more as ornaments than scale models (though it doesn't stop dealers from advertising them as such) 

The model has quite a few other "issues", not the least of which is that it has 12 cannons on the main deck! Evidently the maker misinterpreted the scuppers on the bulwarks as gun ports. (The real ship actually does have a cannon, but only one - a brass 4-pounder signal gun on the poop deck)

  • Member since
    March 2003
  • From: Illinois
Posted by wjbwjb29 on Sunday, August 2, 2009 12:49 PM

I found the link to that model of Cutty Sark with the Brass looking plates.

http://www.giftsnautical.com/product.aspx?intprodid=1467

On the Bench:   Trumperter Tsesarevich on deck Glencoe USS Oregon

  • Member since
    March 2003
  • From: Illinois
Posted by wjbwjb29 on Sunday, August 2, 2009 12:40 PM

Thanks for all the great info on Muntz metal. I just bought some copper enamel which I was planing to add some gold to to see if I could Brass it up a bit. The other day I was at a web site that had a Cutty Sark model for sale and the plates were very brass looking. That is what started this thread.

 

Bill

On the Bench:   Trumperter Tsesarevich on deck Glencoe USS Oregon

  • Member since
    January 2006
Posted by EPinniger on Sunday, August 2, 2009 9:26 AM
An alloy of 60% copper and 40% zinc would definitely have a very brassy, rather than copper, appearance when new. (The term "brass" more or less applies to any yellow-coloured copper alloy where zinc is the main alloying metal. If the copper is alloyed with tin, it's bronze, though many bronzes have a brassy-yellow colour, including the bronze used for some ship propellers). So, if you're building a pristine and unweathered model of Cutty Sark "as built" then a brass colour would probably be more appropriate for the hull bottom plates.
I don't know if any paint manufacturers produce a convincing "brass" colour - most yellow metallics are more gold in appearance. Games Workshop (UK) produce an acrylic paint named "Brazen Brass" which is a very close match for the phosphor-bronze commonly used for ship propellers, but it's probably too coppery in tone for Muntz metal. Possibly a mixture of copper and gold metallic paint might give the right effect.

Regarding the hull plates remaining shiny when in water - I suspect there's some truth in this. The erosive effect of salt water inhibits build-up of oxidation - I've dug up old coins and copper boat nails on the beach which have a bright copper appearance, though they lose their shine quite quickly when exposed to air. The appearance is more of a dull matt pink than bright polished copper. Around the waterline of the hull, where the plating is often exposed to air, there would presumably be greenish corrosion.
Another factor which might affect the appearance of the hull plates is that when copper alloys such as brass are in a corrosive environment, the more reactive alloying metals such as zinc are leached out of the surface, giving the metal a more coppery appearance than it normally would.
  • Member since
    January 2005
  • From: Tampa, Florida, USA
Posted by steves on Sunday, August 2, 2009 7:41 AM

For what it's worth there are some color photos of the hull posted here:

http://smmlonline.com/reference/walkabouts/cutty_sark/cutty_sark.html

These photos were taken some years prior to the current restoration and probably show the "Alumbro" jtilley refers to. Obviously, there are all sorts of pitfalls in trying to determine actual colors from photographs on the internet, etc.

 

Steve Sobieralski, Tampa Bay Ship Model Society

  • Member since
    May 2003
  • From: Greenville, NC
Posted by jtilley on Saturday, August 1, 2009 8:02 PM

In another thread recently ( /forums/1158233/ShowPost.aspx ), I made reference to a most interesting and valuable article, "The Restoration of the Cutty Sark," by Frank G.G. Carr.  Appended to the article in the reprint version that I have are several comments from experts whom Mr. Carr consulted during the last major restoration project, back in the early sixties.  One of those commentators was a metallurgist, Professor A.G. Dowson, M.A., Ph.D.  His comment regarding the bottom sheathing:  "Mr. Carr asked me a few years ago to go and look at the copper bottom of the Cutty Sark, which had then been installed at Greenwich for some time, because it was as he put it in meallurgical layman's language, 'rotting.'  Indeed it was; it was very very rotten.  It is not strictly a copper bottom, it is of Muntz metal, 60 per cent copper and 40 per cent zinc - what we call an alpha-beta brass.  This is cheaper than copper (because zinc is cheaper than copper) but for this purpose, not so good, as can be seen from the subsequent history....

"Replacement of the rotten plates has been done in a material called 'Alumbro' an aluminium-bearing brass which does not contain the high zinc content which led to the failure of the original material, and which precludes any sort of preventive measures."

From George Campbell's China Tea Clippers, pp. 222-224:  "The copper sheets [in the early days of metal-sheathed bottoms] were originally nearly pure copper which eroded away quickly even though it kept a good clean bottom, the marine growth being shed along with the eroding copper.  This was an expensive process and efforts were made to reduce the rate of erosion, or exfoliation, by adding other metals.  Muntz introduced a mixture of 50 parts copper to 50 parts zinc in 1830, and by 1846 had changed it to 60 of copper and 40 of zinc, which was the well known Muntz metal in use up to modern times, sometimes with a proportion of tin added.  Lloyd's Registers of the period describe ships' bottoms as being yellow metalled, coppered or brass bottomed, all these being slight variations...."

There seems to be minor disagreement here over just why Muntz metal replaced copper as the preferred sheathing metal, but modern historians are, I think, pretty generally agreed that it happened well before the construction of the Cutty Sark.  (Another good source on the subject is William Crothers' The American Clipper Ship.)

The American Heritage Dictionary defines "brass" as "a yellowish alloy of copper and zinc, sometimes including small amounts of other metals, but usually 67 percent copper and 33 percent zinc."  Sounds to me like brass and Muntz metal were mighty close to being the same thing.

Just what the stuff looked like after it had been on the ship for a while is an interesting question that modelers have been arguing about for years.  My recollection of the few visits I've actually made to her (in 1978, 1987, 1991, 1992, and 1997) is that the sheathing metal was a mottled, uneven mixture of dark greens and browns - but I was looking at the "Alumbro."  Some authors claim that sheathing metal was normally bright and shiny unless the ship was taken out of the water.  (I'm not sure I buy that one, but I can't disprove it.)  There is, to my knowledge, one photo of the Cutty Sark during her active years that shows the sheathing fairly clearly.  It's an 1872 shot, taken when she was in drydock shortly after losing her rudder at sea.  The sheathing metal appears quite noticeably lighter than the black paint above the waterline.

I don't think I've ever seen a model sheathed with brass sheet, but the truth of the matter seems to be that, in representing the sheathing in its original state, a brass color would be more accurate than copper.  Modelers have used all sorts of techniques to replicate the greenish and brownish colors that (they think) the sheathing acquired later.

I'm not sure that helps much in practical terms, but it's about the best I can offer.  The bottom line is that this is a phase of ship modeling where there's considerable room for personal opinion and taste.  Good luck.

 

 

Youth, talent, hard work, and enthusiasm are no match for old age and treachery.

  • Member since
    June 2009
  • From: Joplin, Mo
Posted by figure freak on Saturday, August 1, 2009 4:06 PM
the bottom of the cutty sark was plated in copper
  • Member since
    March 2003
  • From: Illinois
Color of bottom plates on the Cutty Sark
Posted by wjbwjb29 on Saturday, August 1, 2009 11:40 AM

Hello;

Does anyone know what the color of Muntz metal is. Is it more of a brass color rather than copper color.

 

Bill

On the Bench:   Trumperter Tsesarevich on deck Glencoe USS Oregon

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