Sealing copper plates that have been patinad

[DaveBaxt]

I am considering creating a patinad look to copper plates and have seen excellent results using miracle grow( plant ferilizer) and red wine vineger. However once the required patina look is achieved what is available to seal this to prevent further corrosion or change in colour which will not react with the patina. I have seen available coatings such as Everbrite or Simple coat  but don,t think these are available in the uk. So what is? otherwise perhaps shellac or polyurathane can be used but unsure if I want anything with a gloss or semi gloss finish.I came across this product . Unsure as it is very expensive. https://www.goldleafsupplies.co.uk/metal-effects-permacoat-extreme-473ml-4318/

Another but cheaper https://www.amazon.co.uk/Rustins-5890135-HHW-Metal-Laquer-125/dp/B004ZK4F3O/ref=sr_1_3?crid=3G2OMDBVVVRU3&keywords=copper%2BPatina%2Bsealer&qid=1688634024&sprefix=copper%2Bpatina%2Bsealer%2Caps%2C102&sr=8-3&th=1

What do you guys think?

      Thank you best regards Dave

Edited July 6, 2023 by DaveBaxt

[wefalck]

Personally, I would not coat it, as this changes the surface appearance and takes away from the patinaed metal appearance. Also, a surface treatment might deepen/darken the colour, as it will fill the pores and directs incoming light deeper into the patina (similar to an optical fibre), so that less light is reflected.

 

Apart from that, I think museums use micro-crystalline wax. I would not know any product name, but you can google for its availability in the UK.

 

Normally, metal surfaces were sealed against (further) oxidation by zapon varnish, but the surface would be glossy, something you probably don't want this case.

 

Applying satin or matt acrylic varnish could be another option. Once dry the varnish is inert and should not interfere with the patina. Not sure how well it might stand handling.

 

In any case, I would test the effect first on a scrap piece of copper.

 

[rwiederrich]

These techniques are good for copper plated hulls....but Muntz covered hulls oxidized very differently and actually tuned a metallic brown.  No green patina.

 

Note this on Cutty Sark.  

[rlwhitt]

4 hours ago, DaveBaxt said:

I am considering creating a patinad look to copper plates and have seen excellent results using miracle grow( plant ferilizer) and red wine vineger. However once the required patina look is achieved what is available to seal this to prevent further corrosion or change in colour which will not react with the patina. I have seen available coatings such as Everbrite or Simple coat  but don,t think these are available in the uk. So what is? otherwise perhaps shellac or polyurathane can be used but unsure if I want anything with a gloss or semi gloss finish.I came across this product . Unsure as it is very expensive. https://www.goldleafsupplies.co.uk/metal-effects-permacoat-extreme-473ml-4318/

Another but cheaper https://www.amazon.co.uk/Rustins-5890135-HHW-Metal-Laquer-125/dp/B004ZK4F3O/ref=sr_1_3?crid=3G2OMDBVVVRU3&keywords=copper%2BPatina%2Bsealer&qid=1688634024&sprefix=copper%2Bpatina%2Bsealer%2Caps%2C102&sr=8-3&th=1

What do you guys think?

      Thank you best regards Dave

 

Hi Dave,

 

As I'm about to need to think about this in my current project, I'm intrigued by your mention of Miracle Grow and vinegar.  Do you have the specifics of the receipe handy?

 

Thanks!

[DaveBaxt]

here is the Link where David has posted his mixture and the results of using miracle grow and red wine vinegar. 

 

[GrandpaPhil]

Copper plating will patina on its own, even under sealant.

 

I sealed my last coppering with Delta Ceramcoat sealer.

 

It worked really well for me.

 

The copper got a really nice patina within a couple of years by just aging naturally.

Edited July 11, 2023 by GrandpaPhil

[Jaager]

I would guess that it would be a tedious process,  but to reduce the chemical acceleration back to ambient rate , would not a neutralization step be needed?

A treatment with a dilute sodium bicarbonate solution and a couple of rinses with distilled water?

 

 

 

[Bob Cleek]

In my experience, once a yellow metal develops a patina, i.e. oxidizes, the oxidation on the exterior, i.e. the patina, becomes a sealer itself and further oxidation apparently ceases or at least slows way down. In other words, the patina is the sealer. There's no need to seal the patina at all. Now, perhaps some of the chemists and metalurgists in this forum can explain this phenomenon, or expose it as pure bunk, but I've handled a lot of patinated copper and bronze over the years and if it's a patina you want, the best was to get one and keep it is to just leave the piece alone. Surely exposure to salt air, for example, can accelerate the oxidation and keeping it indoors will avoid the green verdigris affect, yielding a "brown penny" look instead, but it all oxidizes the same. Nobody's painted a clear sealer on the Statue of Liberty as far as I know and she's doing just fine.

 

Brass horn players will probably disagree with me, but I wouldn't advise lacquering or otherwise coating polished yellow metal at all. For one thing, bare brass or bronze, lightly polished regularly, will take on a beautiful character owing to those few areas which aren't accessible to the polishing cloth. Hinges, screw slots, and deep corners all develop their own contrasting character to yield a "well used and well cared for" look. The "perfect" bright lacquered finishes that are often applied by manufacturers quickly degrade to a blotchy visual horror because of microscopic scratches and other porosity occurring in the coatings applied. I expect most mariners are familiar with a shiny brass clock or barometer case that after a few years looks like it has "the pox." Because of the coating, it is near impossible to polish these spots away. There's nothing for it but to strip off the coating entirely. This is also often an extremely difficult and time consuming process. Some lacquers wipe off easily with a liberal application of lacquer remover, but others cling to the surface like it was life itself.

 

Every lamp, barometer, ship's clock and other brass or bronze item I own is, or eventually will be, stripped of their factory clear coatings and reduced to their natural bare state and then lovingly (but perhaps too infrequently) hand polished. The satisfaction of polishing a nice piece of brass to a mirror gloss is hard to beat.

 

The moral of the story being that if you coat patina, that coating isn't likely to be accomplishing anything in the short term and probably will cause a whole lot of work for your or some subsequent owner in the years to come.

 

If it's a weathered copper bottom you are seeking, you may also wish to consider applying scale-thickness paper "plates" and painting these with an airbrush and standard model weathering products rather than trying to achieve that look on a model hull with real copper plates. Most of the commercially available "real copper" plates produced for ship modeling are eggregiously out of scale in the first place. Patina itself has its own scale as well. Study your model's bottom and determine what a weathered coppered bottom of your model's scale actually looks like when viewed from scale model viewing distances. When it comes to depicting coppered bottoms, subtlety is the name of the game.

 

 

See: 

 

[Roger Pellett]

Not a metallurgist but an experienced industrial metal fabricator.

 

The mechanism is oxidation caused by exposure to oxygen ions (air, water, etc).  Corrosion resistant materials “work” by forming an oxide film bonded to the substrate that isolates it from the corrosive source.

 

Metal fabricators take advantage of this property to finish surfaces.  For example, specifications for stainless steel nuclear service piping often require that the pipe be “pickled and passivated.”  This is a two step operation.  The pipe is first cleaned in  tank of hydrofluoric acid.  This is followed by passivation in Nitric acid.  The dull grey color of stainless steel is this corrosion film.  Unfortunately, when this film is damaged accelerated corrosion exists between the protected and unprotected surfaces.

 

I am less familiar with copper and brass alloys but suspect that they form similar  protective corrosion films.

 

Roger

[Bob Cleek]

5 hours ago, Roger Pellett said:

I am less familiar with copper and brass alloys but suspect that they form similar  protective corrosion films.

 Thanks, Roger! That's always been my layman's understanding of it as well.

[DaveBaxt]

Sorry I have not replied to this sooner. But a thank you to all people who  have particicipated in this discussion and also something which I would like to carry out a few experiments of my own to see what looks best from a distance. I have already done some test of just painting with an airbrush a mixture of weathered copper ( brown) and verdegris which I think was quite pleasing. However I am still not totally convinced this is the best way forward. Another thing which I am unsure is whether or not to seal the wood prior to gluing any  copper tape or plates and have considered using shellac but wonder if this is necessary .

Edited July 12, 2023 by DaveBaxt

[Snug Harbor Johnny]

  Looking at two photos of actual metal plated hulls (as seen from a few yards away ... which might represent someone taking a relatively 'close' look at a model), the appearance is quite smooth.  Seriously, the outlines of the individual plates are barely perceptible - and the tiny nails are all but invisible.  Sure, if one can get right next to a plated ship in dry dock - close enough to reach out and touch the plates - you can see and feel the overlaps and nail heads ... but for a model, one would have to go through 'Wonka Vision' and be shrunk down to HO scale to get that close.

 

  A miniaturized person examining a model plated with individual copper plates would remark how thick the plates are and how large the divots (representing nails) are.  On actual ships the copper (or Muntz metal) is, what, 0.032" ?  At 1:96 you'd need 0.00033" (that's 1/3 of a thousandth - less than the thickness of a human hair ! ) material to be in scale - and 1/8" nail heads would shrink to only 1.3 thousandth of an inch - about 1.7 times an average hair thickness.  (I'm not going to convert to millimeters.)

 

  Of course, there are many scale compromises that often are made in many scales - meaning that dead eyes, blocks and belaying pins often are are a bit 'out of scale' (sometimes more than a bit), so I suppose that plates and copper tape are no exception.  'Seems that on a solid-hull model (or a completely 'filled' plank-on-frame below the waterline, one could merely use a fine stylus (with a straight edge as a guide to follow very fine layout lines) to scribe rows of plating and then add vertical division.  An X-Acto knife would also work.  Spray painting a brownish base coat followed by green overtones would be perfectly acceptable for the bottom of a hull - which is not where most observers are looking. 

[Bob Cleek]

It's always been my impression that the current practice of coppering model ship hulls was the result of nothing more than some European kit manufacturers taking the opportunity to throw a little bit of copper foil into their boxes so they could advertise "Real copper included!" and add substantially to the "number of parts included" by counting each copper plate.  

[Roger Pellett]

If you plan to use pressure sensitive adhesive copper foil tape I really think that you’re doing things the hard way to achieve questionable results:

Longevity-  All pressure sensitive adhesives are suspect

Scale- See Johnnie’s Post above

Nails-  At model making scales, best left off

Weathering- difficult to achieve scale effect

 

I would use acid free paper stiffened with shellac.  Cut it into plates and glue down with PVA glue.  You can then paint with airbrush to achieve wanted effect.

 

I agree with Bob that copper foil in model kits is just a marketing gimmick.

 

Roger

[Bob Cleek]

2 hours ago, Roger Pellett said:

I would use acid free paper stiffened with shellac.  Cut it into plates and glue down with PVA glue.  You can then paint with airbrush to achieve wanted effect.

In my experience, shellac alone is an entirely sufficient adhesive for gluing down paper "plating," and it dries much faster than PVA.