Boiler Paint Question- Sorry

I appreciate paint has been discussed to death but I’m struggling to find a definitive answer from the searches I’ve done.

I’d like to spray paint the boiler of my DR Mercer Type1 Traction Engine in British Racing green or similar dark green colour. I’ve searched engine paints in this colour as obviously I don’t want the paint bubbling up when the steam engine gets hot and the one that keeps popping up is E-Tech engine paint. The problem is it says it’s not suitable for non ferrous metals including brass. My traction engine has a brass boiler. I’ve also looked into how to prepare and spray brass and it says to use an etch primer. All the high temperature paints say they can be painted with no primer. I’m concerned that if I use an etch primer it will react when the boiler gets hot and if I don’t use an etch primer on brass any high temperature paint won’t bond to the brass.

My question is 2 fold. What spray can anyone recommend and what is the correct way to prepare a brass boiler for spraying. I’d rather spray it than brush paint because I don’t want brush marks in the final finish. I’d also rather an aerosol spray because I currently don’t have an airbrush or spray gun. Although this could be a good excuse to buy one.

Thanks,

David

It would not have a brass boiler so I presume you mean brass cladding on the copper boiler. If so, I would use etch primer and quality spray enamel. I used Humbrol on a Gauge 1 gas fired loco and while heat has changed the colour somewhat, it is still perfectly sound looks good. The builders I know don’t bother with high temperature paint. I did use HT black on a 5” gauge steel smokebox and I did use etch primer first.

Thanks Simon. Ok that’s great. I’m a complete novice when it comes to steam and model engineering. This engine belonged to my late father in law and I’m on a steep learning curve with this. If it’s just cladding around the boiler and therefore won’t get so hot then that gives me more options if I’m not limited to VHT type paints. As you’ve said, I’ll look at enamel sprays.

The Mercer is a “pot boiler” type of boiler, and certainly mine is made from brass.
I insulated it and clad it with thin shim steel - which is then straightforward to paint. Also made a huge difference to the steaming - as the flame is under one end and the boiler stick out is exposed to the ambient air.

For what it’s worth mine was primed with Craftmaster etch primer, then top coats were enamel iirc.
That was quite a while ago, when John at Minsteam was still working with Phil at Craftmaster.

John doesn’t do technology, but I’m sure Sarah will respond to an email asking what they currently use.

Dave

Thanks Dave, out of interest what did you use as insulation? I’ve got some material that’s used as breather cloth for bagging up composite repairs here (nicknamed Father Christmas beard). It’s heat resistant and I’m wondering if that would be sufficient as an insulator. I’ve also got an old roll of steel shim in a tin in the garage. I’m trying not to over complicate this little project though.
I’ve been in touch with John and Sarah at Minsteam previously for some odd parts for this engine and they were very helpful. I’ll try getting in touch with them again and ask them what they use for painting these engines.

David

From memory I bought some thin ceramic lagging from Reeves or one of the other normal suppliers. It’s about 2mm thick. I used the supplied boiler bands, but I think I had to use slightly longer bolts to join them.
I only clad the sticking out part - the bit in the “firebox” is left as is and so I don’t think the cladding needs to be super heatproof - at 15psi the steam temp is not much above boiling water, so by inference the boiler shell can’t be either. Prior to lagging I had just painted with etch primer and enamel, but trying to run it outside was dependent on it being a warm, still day.

I used bike pot black engine paint for the firebox area, with dark green on the driving position/ tender - just a masked line straight down from where the levers attach.

Just looked and the enamel I used was Plasti-kote projekt paint fast dry enamel. Came from Wilkos for 1.99 something like 10 or 15 years ago!

Dave