Painting and priming

[bordercollie]

Hi
Whilst realising that they are several ways of doing anything, I am a bit confused as to what primer I should use. Would it be right to use car grey primer on plastic and etch primer on etched brass? Does the primer allow any tarnishing on the brass to be painted over?
Regards

[bordercollie]

Hi
Since starting thread I have realised that this topic has been covered in the past.
I would still like to know if priming over brass tarnishing would work and that painting would no be compromised in any way
Regards

[Daddyman]

In one of the modelling magazines 10-15 years ago, someone's preparation of the brass body of an 0-gauge J94 for painting was to deliberately tarnish the model as much as possible, though I can't remember what preparation he used. Obviously, we have no idea how long the topcoat lasted, or how smooth the finish was. It's certainly not something the professionals advocate - Ian Rathbone in his book insists on a shiny surface before priming, and goes through his process for achieving that. I thought the model I sent him was very clean, but he said it was the dirtiest he'd ever seen (I never did get that prize), including tarnishing, and set about cleaning it himself.

You could ask on this active thread on Western Thunder - at least 3 professional painters are contributing at the moment, but I know from the pics they post of models prior to painting that they're immaculately clean:
https://www.westernthunder.co.uk/thread ... ost-272824

Alternatively, try it on some scrap - one half tarnished, one not. But that raises a question: why do you want to hang on to the tarnishing? By the time you'd set up the experiment you could have cleaned the tarnish off.

[jon price]

Surely the point of an etch primer is that it etches (ie tarnishes) the surface of the metal, so polishing the surface to a state where it won't take paint, then using an etch primer is simply going round in circles. Dipping the brass in an etching fluid (ie a mild acid) followed by a coat of the right colour primer would achieve the same result with more speed and less labour. Where you do need to clean up is any excess solder.

[Enigma]

Where you do need to clean up is any excess solder.

And flux deposits - which is not always that easy. I've used metal blacking as a surface coat on brass which seems to work better than the plain surface. I've had paint peal away with masking tape before now (Tamiya tape) if I've not used a good etch primer.