varnish coat for copper plates

[georgeband]

I am building a 1/64 schooner (HMS Whiting, 1805) and have used the Amati copper plates. Plating is now nearly finished and is described on my build log. 

I don't want to restart the discussions about what the copper should look like; my personal choice is to start with bright copper and let it slowly tarnish over the years. The Amati plates have a restrained nail pattern which I like. The model will be in a cabinet when she is completed. 

 

I want to give the plates a coat of some varnish for two purposes:

1. Protect the copper from my fingers while I continue to work on her. I have worn cotton gloves during the coppering and they do impede the modelling a little, so I prefer to have bare fingers for the upper works. There are a few fingerprints already forming on the copper which I will clean off before varnishing. The varnish should prevent more from appearing. 
2. Slow down the tarnishing process. I know that I cannot stop it easily and I have thought about filling the display cabinet with nitrogen (no oxygen) but that is taking things a bit too far. I am prepared to accept the inevitable colour change. 

 

I know from experience that copper pipes do not like water based paints (emulsions or gloss) and quickly go green. I have given some copper pipe a coat of matt acrylic varnish to see how it reacts over the next few weeks. I don't have a polyurethane varnish to hand but will probably try that too. 

 

Does anyone have words of advice about a suitable varnish?

 

George

[BenD]

I believe I have some knowledge to share on this. The test piece bellow is still stable and has no change in a appearance after many years. It was water based polyurethane, the dark spots were the same but with some brown paint added to the mix. However I ended up taking the coating off of my HMS Snake with 100% Isopropyl alcohol. I didn't like the look of it in the end. The first coats made the tiles look pink so I added a few layers with brown... I still did not like it.  

 

The tiles will be protected from moisture and other environmental grime as long as the varnish sticks to the metal.

[Jaager]

You could try applying a coat or two of shellac now to protect against finger prints and when the model is complete, use EtOH to remove it and let our atmosphere get at it.

[vaddoc]

I applied Renaissance wax to polished brass fittings. Many years later, they are still as bright! This wax is also completely invisible and very hard. I vaguely remember reading somewhere that this is what museum use to keep metals from tarnishing.

[georgeband]

Thank you all for your comments. 

I have followed up on the Renaissance wax, Vaddoc, and it is the preferred museum finish for metals, so it should be good enough for a model. I have ordered a tub and will also try it on a replica sea-service pistol that I have. 

Thanks again,

 

George

 

 

[wefalck]

I think you have two contradictory requirements there: either you (properly) varnish the copper and it will stay bright for many years, or you don't varnish and it will tarnish to a dull reddish-brown, if not touched.

 

The traditional varnish for metal objects (silver, brass, copper, etc.), including those handled, is what is called zapon-varnish: http://cameo.mfa.org/wiki/Zapon_lacquer. 

 

I have model parts varnished more than three decades ago with it and they are still as bright as on the first day.

[georgeband]

Thanks for your suggestion, Wefalck. Zapon is new to me and a quick Google search suggests that there are few suppliers. I will try the Renaissance wax first and see how easily that goes on. 

 

I have a second question on the same theme: how to prepare the copper plates before varnishing or waxing? My thoughts are to degrease with meths applied with cotton buds or a cloth, and use a fibreglass brush to remove residues from the cyanoacrylate glue where it has dried on the surface. Any advice on this aspect?

 

George

[wefalck]

Yes, don't use the fibre-glass brush, it will badly scratch the copper. The plating can be polished using 0000 grade steel-wool.

 

Acetone is a better degreasant than alcohol and also removes CA glue - but use it sparingly, as acetone penetrating the joints could loosen the bond between the hull and the copper.

 

Also do not use CA to stick the copper to the hull - CA is brittle and the bond can break, when there is a temperature change. Perhaps not now, but in a few years time. It is better to use a contact cement.

 

Not sure, what Renaissance Wax really is, but if it is a wax, it may be very difficult to remove, if you are not happy with the result.

 

 

[Jaager]

4 hours ago, wefalck said:

Not sure, what Renaissance Wax really is

It is a very fine and very hard wax mixed in an organic solvent - it is a bit thicker than Vaseline - the solvent evaporates fairly quickly -  but would be no fun atoll to try to remove

[georgeband]

A can of Renaissance wax was delivered today and the instructions say that the wax is easily removed with white spirit, so a mistake can be rectified without too much trouble. (Or no worse than removing a varnish; I did that recently for a whole hardwood floor.) I also now have some grade 0000 wire wool and will set up some experiments to look at scratching (wire wool vs. fibreglass brush) and resistance to salty air which we have in our garden (weather dependent). The experiments will be on copper pipe and not the copper plates I have fitted to Whiting and I will present the results when I have them. 

 

Thanks all for your advice. 

 

George

[georgeband]

I have compared the surfaces cleaned with grade 0000 wire wool with those from a fibreglass brush. With naked eye I cannot see the scratches but the fibreglass surface has a duller appearance. The good news is that applying wire wool after the fibreglass brush returns the surface to the same lustre. This might be because the finer cut from the wire wool removes the deeper scratches from the fibreglass, or because the wire wool burnishes the copper and 'squeezes' the scratches, or a combination of both. This gives me the option to use the wire wool first, find where there is CA glue dried on the surface, cut back the CA with the fibreglass brush and then blend it all together with the wire wool. 

 

The Renaissance wax goes on easily and I have applied three coats. I might yet apply some more if I feel pessimistic. 

 

Two photos below are before cleaning and after waxing

 

 

George

[wefalck]

I think your strategy for cleaning up the coppering and the interpretation of what happens during the burnishing with the steel-wool is correct. I observed the same.

 

[rwiederrich]

I too wanted to prevent the shiny unprotected copper plates from tarnishing unduly...especially with fingerprints...yuk.

But also my time period did not use *copper* plates, but Muntz metal plates...which were more brassy and *Yellow*, then copper.

 

So to protect them and to make them more tarnished as was muntz when it oxidizes.  I protected and recolored the metal to mimic oxidized muntz.

 

Here are some pics of what I did when I *coppered* my 1/96 Glory of the Seas.  I used metalic paint to lightly cover the plates.

 

 

 

Rob

[georgeband]

Rob,

 

Your photos of Glory of the Seas are not visible at the moment. Some mistake with downloading? 

 

George