copper sheathing - weathering

Oh, boy.  This is a complex, interesting, and somewhat controversial topic.

To begin with, we need to note that not all the sheathing metal applied to sailing ships' bottoms was in fact copper.  Copper was the first metal that came into widespread use for that purpose.  In the middle of the nineteenth century, though, copper ("red metal") started getting replaced by "yellow metal."  This apparently took several forms, which probably varied a bit in color.  "Muntz metal," introduced in 1830 (my source is George Campbell's excellent book, China Tea Clippers), was 50% copper, 50% zinc; in 1846 Muntz changed the formula to 60% copper, 40% zinc.  Mr. Campbell says tin was somtimes added to the mix.  Lloyd's Registers of the nineteenth century included notations on the sheathing of ships, and used abbreviations for "yellow metal," "copper," and "brass."  (Brass, according to the dictionary I have in front of me, is typically 67% copper, 33% zinc.)

So what did it look like?  Some modelers think - and they have some pretty impressive photographic evidence to back them up - that the manufacturing process introduced a considerable variation in color before the metal was put on the ship.  In nineteenth-century photos of metal-sheathed ships on the launching ways, the individual plates do indeed look different - some much lighter than others.  Some modelers replicate that effect by heating their copper sheets with a torch before cutting them into individual plates.  I personally don't care for the result that technique produces; it makes the bottom of the ship look like a patchwork quilt.  I also have a suspicion that lighting conditions had a lot to do with the color variations that show up in those old photos.

Anyway, when pure, bare, untreated copper is exposed to the atmosphere it starts to oxidize.  Within a few months it acquires a fairly smooth, even patina that's a remarkably bright, medium green in color.  (An historic house in the town where I live got a new, replacement copper roof about a year ago.  It's already turned green.)  Brass, when exposed to the atmosphere, turns black eventually, passing through various shades of greenish brown in the process.  The proportion of the various elements in the metal affects the weathering process; so does any sort of surface treatment the metal received during the manufacturing process. 

Michel's barrel is most interesting.  I don't recall having seen a piece of copper that's weathered in precisely that way.  I wonder if it went through some sort of chemical treatment at the factory, or if perhaps there's some additional element besides copper in it. 

What did the bottom of a copper- (or yellow-metal-, or brass-) sheathed ship look like after it had spent some time in salt water?  I honestly don't know - and I'm not convinced anybody else does.  Part of the theory of metal sheathing was that the ship's movement through the water would constantly erode the surface of the metal, so fresh metal would be exposed to the water all the time.  I don't swallow that entirely.  We know that various forms of marine growth managed to hang onto the surface of the metal.  (There are some well-known stories about warships being handicapped in sea fights because their copper was "foul.")  I can recall seeing only one ship with a genuine metal-sheathed bottom that had been sitting in salt water for a prolonged period:  the Charles W. Morgan.  I'm not sure what kind of metal is on her bottom these days; it probably isn't exactly the same stuff that was used in the nineteenth century.  At any rate, as I remember them, the plates have turned a mixture of dark brown and green, in quite a variety of shades.  (The other metal-sheathed ships I've seen either have been drydocked - like the Cutty Sark and the Victory - or have had their plates painted - like the Constitution and Constellation.  The latter came out of her latest restoration with her bottom painted bright green.) 

The color probably varied depending on whether the ship was at sea or had been anchored for a lengthy period - and certainly would start to change rapidly if the ship were taken out of the water.  In theory, I suppose, we ought to figure out just what we're trying to represent on a model.  Do we want to show what it would look like at sea - with the surrounding water removed?  Or have we lifted it out of the water, so the air can have its effect on the metal?  In any case, given the nature and quantity of stuff that probably was stuck to the ship's bottom in real life, I'm not at all sure a literally accurate representation of it would be something I'd want in my living room.

Two of my models, pictures of which Michel was generous enough to post on his website ( www.hmsvictoryscalemodels.be/johntilleygallery.htm ) , show different approaches to the problem.  The Bounty (which is known to have been coppered - though the designers of the Revell kit didn't know it) is plated with .001" copper sheets, applied to the plastic hull with contact cement.  (It's now stuck quite firmly for about 28 years.)  I painted it with Poly S acrylic hobby paint (no longer available, but PolyScale is close) in lots of shades of green, brown, and grey, applied "dry-brush" fashion in vertical strokes. I was trying to make the hull look as though it had spent considerable time in saltwater.  If I were aiming for that effect on a plastic kit with a good representation of copper sheathing molded in, I'd probably paint it the same way.  I wouldn't use copper paint; my personal opinion is that the metallic sheen would be gone from the surface after a short period. 

The Phantom is based on the (no-longer-available) resin-hulled kit from Model Shipways.  It came with a spool of (allegedly) copper foil tape with a pressure-sensitive adhesive on the back. It was twice as wide as it should have been, but after I cut it in half it worked quite nicely.  I think the material is the same stuff used in stained glass windows.  I don't know what's actually in it, but I suspect it is in fact copper that's been subjected to some sort of treatment that wards off the effects of oxidation.  (Stained glass window makers don't want their copper to turn green.)  I decided to see what would happen if I just applied it to the model and left it.  So far (three or four years later), so good.  It's gotten noticeably darker, but still looks metallic and shiny.  I figure that's about what a freshly-coppered bottom would look like.

I'm afraid this ridiculously long post hasn't shed a great deal of light on the subject.  The bottom line, I think, is that the treatment of a "copper" bottom leaves plenty of room for interpretation, guesswork, and personal taste - the sort of thing that makes this such an interesting and enjoyable hobby.

 Four months ago, I submerged a piece of copper pipe in a bath of sea salt and water, to see what would happen. The piece is now  the typical color of copper pipe that has been around for a few years, a flat red-brown, with just a touch of light green here and there. Floquil "tuscan red" looks like a good match. I was expecting something a little less plain. The piece was submerged, so it was not exposed to air, and did not truly oxidize. I would suspect that copper sheathing on a hull would take on the red-brown color, except where it was routinely exposed to the air ( rolling and pitching ), close to the waterline, here, the light green oxide would probably be pronounced. In any event, I plan to use the Tuscan Red, and drybrush the light green at the waterline, when I paint the hull of Surprise. I might drybrush some copper in places where the plating may have been able to come in contact with anything that would abrade the dull finish off, most likely around the bow, or possibly where a small boat might have rubbed the plating as it were lowered, or hoisted back on board.

I think that's as good an approach as any.  As I said earlier, I'm not convinced that anybody really knows what color the bottom of a real copper-sheathed ship of the nineteenth-century was.  I suspect there was some difference in chemical structure between what those folks called "copper" and what goes into modern plumbing components - but I don't know what the difference might have been.  The motion of the ship through the water may indeed have had some effect on the coloration of the metal - but I don't know exactly what.  The presence or absence of various kinds of marine growth must have had a big effect on the color - and the type of marine growth would vary according to the regions to which the ship traveled.  And whatever color it was after three months in the water, it probably was some other color a year after that.  I'm not going to argue strenuously with any shade of green, brown, or dark, dull red.

Thank you, gentlemen,

another problem when weathering is the scale, we often see the same weathering effect applied all along the hull, with large brush marks, giving a "not to scale" look.  We work here in small scales, and there must be (if we decide to do it) tiny spots of dark brown/black/green, plate by plate.  But, I think, verdigris would appear as irregular, thin stripes, along the waterline and in the holes.

BTW, Sumpter, I could read somewhere, a process to accelerate the process of oxidation : dip during one day or two the copper plates in a solution of vinegar saturated with salt. I can try to find the proportions, if you are interested in it.

Michel

 

I think I remember one old modeling tome (I don't recall which one) that recommended wrapping the freshly-coppered bottom of the model in a cloth soaked in a solution of salt and ammonia, and leaving it alone for several days.  I've never tried that, for several reasons - one of them having to do with domestic tranquility.

I agree completely with Michel's point.  One of the best ways to wreck the "scale effect" of a ship model is to make the "weathering" out of scale.  That goes for all other forms of weathering, as well as the "copper" sheathing.

Michel, craft stores sell some solutions for aging copper. It's worth looking at if you're using real copper. I got some copper in a roll from a craft store that's used for metal punching. It's thin, very soft and forms easily.

 The earliest penny in the collection my father passed on to me, is a 1909. It is the same color as the copper fitting I had soaked. Now that I think of it, the only places I have seen the "Green effect" is copper exposed to the "elements", sun, rain, air. 

   The subject of weathering also gets a lot of kicking around on most of the model railroad forums. The point of "scale weathering" is well taken. To really know how to weather something, you almost have to see it ! Rain, weathers, Sun weathers, Wind weathers, accumulation of dust, and dirt weathers, Chemicals in the air, and dirt weather. Where has your "thing- to- be- weathered" been ? what has it done ? what was it exposed to ? What, where, when, how, with what, under what circumstances, how long, and how much, and how did it get there, and when it hit, how far did it run? Did it cover completely?, or collect in pools? Is it only on vertical surfaces?, or only on horizontal surfaces? AArrrrrrrrgghhhh.

  Methinks, 'tis time, and a prudent venture at that, to lay up close in the lee of a great headl'nd, and if for nought else,but to rest a bit, and take a deep breath afore settin' to it again,... back into the teeth of the gale. If he who would pun, would pick a pocket, then pick a pocket I will....in the turn of this encounter, I'll have to yield the "weather" gage. (or is that "weathered" gage}

I've seen pennies that have turned brown, green, and almost pure black.  I don't think the penny is made of pure copper (though it may have been in 1909).  And I'm not at all convinced that the stuff nailed to the bottoms of ships was pure copper either. 

This topic could go on forever.  I think we've covered the most important aspects of it.  The point is not that there's one "right" way to do it, but that it leaves considerable room for personal interpretation and taste.  Let's build models.

Keep in mind that a ship with well weathered copper would also likely be somewhat baracle encrusted, with missing copper plates here and there, and likely show a separate streak of weathering near water line (termed "between wind and water") different from parts that ate permanently immersed.

BTW, the first commonly used sheathing matal was not copper.  It was lead.  Some ships has lead sheathing as early as 17th century.

 

 

 

 

Barnacles, seaweed, and lots of other stuff - none of which I'm particularly interested in reproducing to scale - undoubtedly stuck to the surface of the sheathing.  Like I said earlier, a really accurate reproduction of a sailing ship's bottom would not be the sort of thing most people would want to display in their living rooms.

Mr. Lavery, in the relevant chapter of the Conway's History of the Ship volume, notes that lead sheathing was tried quite seriously by the British navy in the 1670s.  He comments that "at one point it looked likely to become standard.  However this took no account of electrolytic action, and several shiops were pput in serious danger because thir rudder ironwork decayed."

When weathering, I would take a look at the green oxidization happening below the waterline.  There is a lot going on down there because of the movement, and friction of the water.  I have seen a copper hull that was oxidized below the waterline.  But I do agree with the scale thing.  You must take the weathering plate by plate at times in order to get the right effect.

I must say I would find it very difficult to weather plate by plate on a model such as the Heller 1:100 Victory.

In my view it's an exercise for the artistic eye and quick strokes built up layer over dry layer using both wash and dry brush techniques.

On this model scale the aim should be to view  the overall effect from say two feet, but I recognise that the smaller scale you work with the more difficult it becomes.

In some ways the colour combination is less important than achieving an overall pleasing corroded look. The trick is not to have clearly defined brush strokes, and an understated approach is better than overdoing it.

Whenever I start on a new project  I use a 'hulk'  to test the effect I'm after before committing to the actual project.

As usual, I agree with George.  I don't suggest that the "plate by plate" approach is necessary or even appropriate.  My understanding of Michel's point (with which I also agree) is simply that the weathering needs to be applied with due regard for the model's scale.  Huge, wide strokes of paint, stretching over ten or fifteen scale feet, will kill the scale effect.  If the weathering is done carefully, and with due regard for the scale, the changes of color and visual texture won't stretch over more than a couple of scale feet; I don't think there's any need to paint each plate individually.