Building and painting/etching brass/nickel silver locomotive chassis

[Rustony]

Happy new year all.

 

I'm currently starting to assemble my first etched brass/nickel silver locomotive kit (CSP Avonside 0-6-0), and I'm not sure about the best way to go about assembling the chassis.

 

From reading around, guidance seems to be that I should use a black acid etching primer (I was thinking of Birchwood Casey Brass Black), but this raises a couple of questions:

1. Generally people seem to suggest dunking the chassis into the fluid, but then this would also etch the brass axle bushings (which I assume should remain unpainted/etched). Can the chassis be etched and then have the bushings inserted after? I would assume that the etching will prevent soldering, so I guess I would need to use CA or something? Alternatively, can I brush on the etchant instead, just being careful to avoid the bushings?
2. How black will the result be? The finished locomotive frames will be black, so will I be able to leave it as-is, or will it still need a coat of paint?
3. There is a white metal component on the frames - is it fine to use the same etchant on this, or should it be added after?
4. Would this be suitable for priming the entire brass body too (the majority of the body will be a battleship-grey colour)?

 

Any input would be greatly appreciated.

[John Tomlinson]

Birchwood Casey Brass Black (or indeed any other of their Blacks), isn't an etching primer, it's a blackening fluid. By that I mean it chemically reacts to the brass to make it "Black". I've put "Black" in inverted commas as the final result won't be black as such, but a greyish brown. The other thing with the Blackening fluids is that they don't work properly unless the surface is really clean, so beforehand don rubber gloves and scrub with kitchen cleaner, and don't touch the surface with your fingers until you are finished. You can apply the fluid with a cotton bud, and keep going until everything has gone dark, or dunk the whole thing - I'd go for the former, as the latter may just make a mess everywhere.

 

Etching primer is something else entirely, being a form of paint that covers the thing being painted as well as chemically etching itself into the surfcae to provide a primer layer for subsequent coates. It is invariably best applied either through a spray can or even better an airbrush (clean without delay afterwards). In common with Blackening fluid it is essentail the surface you are painting is absolutely clean and grease free, so gloves and cleaner and don't touch until fininshed!

 

Etching primer will work on both white metal and brass, so is probably your best bet for the whole job. You'll want to add topcoats afterwards to get a proper job. Personally I use Blackening fluid for litte bits of detail applied to models, and find that for something small that won't be handled I can get away with this plus a dab of paint. I certainly wouldn't do a whole model this way.

 

John.

[ianLMS]

For my brass locos i use Humbrol masking liquid applied with a cocktail stick to protect the inside of the bearings and other areas i dont want painting, then apply a coat of Halfords aerosol etching primer. Then a coat of matt black. The main point it to ensure the brass is super clean before painting. 

 

Blackening fluids isnt permanent and is easily removed.

[Nile]

It's a method used by DLT , see here:

 

[Steamport Southport]

Halfords grey primer and then a coat of Halfords black or enamel black is the usual way. Better still is a primer of your choice sprayed through an airbrush.

 

The only time I've ever used chemicals to "blacken" anything was a few parts such as coupling chains and buffers when I modelled in O Gauge. That was using Carrs Metal Black (quite noxious stuff).

 

For cleaning try Cif (used to be Jif). Just the cream stuff and rinse off thoroughly. It's about £1 in your local supermarket or bargain shop.

 

 

Jason

[Lee-H]

Having tried several chemicals and abrasive materials I found the cheapest, easiest and quickest approach to etching brass is Mr Muscle Max Gel Unblocker. It takes only 5 minutes to etch the surface. Rinse under cold water, dry thoroughly then apply a suitable primer. I use Tamiya Fine Surface Primer and it bonds itself to the brass perfectly. You can then apply your chosen top coat.