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Painting brass

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  • Member since
    August 2013
  • From: Richmond, VA
  • 1,890 posts
Painting brass
Posted by carl425 on Friday, May 2, 2014 1:47 PM

There is a brass locomotive on ebay that has caught my eye.  Problem is that although I've painted dozens of plastic models, I've never painted a piece of brass.  What is the relative degree of difficulty?  What do you clean brass with before priming?  What type of primer do you use?

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

  • Member since
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  • From: Sweden
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Posted by Graffen on Friday, May 2, 2014 1:56 PM

carl425

There is a brass locomotive on ebay that has caught my eye.  Problem is that although I've painted dozens of plastic models, I've never painted a piece of brass.  What is the relative degree of difficulty?  What do you clean brass with before priming?  What type of primer do you use?

 

I usually remove the factory applied clearcoat before painting. I use cellulose thinners, be sure it is ALL METAL!!!

I then paint with either Scalecoat paint or prime with etching primer for the auto industry.

I then bake the model at 145°F. Just be sure there are no plastic parts attached!

Easy peasy!

Swedish Custom painter and model maker. My Website:

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  • Member since
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  • From: Franconia, NH
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Posted by dstarr on Friday, May 2, 2014 2:20 PM

It's harder to get paint to stick to metal than to plastic.   You need to take the boiler off the mechanism to paint.   I don't like to take the mechanism apart, and I don't want to get paint in the motor, gears, rods, or couplers.  I usually brush paint any bits of bright brass gleaming in the darkness under the boiler.

Best possible surface prep is one secret to success.  You have to get every trace of grease (finger prints, gear lube), oil, and with brass, the soldering flux off and keep it off.  I started off by wiping down with solvent.  I needed to use MEK to cut the soldering flux.  Next I pickle the brass in a mild acid, supermarket vinegar works fine and is readily available.  The acid etches the surface of the metal and give some tooth for the primer to grip.  Follow the acid etch up with hot soapy water, and a hot water rinse.  Don't touch the brass with your bare hands after rinsing.  Dry thoroughly, over night at least. 

   First coat wants to be dark gray auto primer from a rattle can.  The auto primer is sold to mechanics who expect it to stick to somewhat greasy car parts.  It has the best stick-to-metal chemistry known to the industry.  There are other primers, but the rattle cans of auto primer are the best you can get.  Spray so the paint goes on just barely wet.  If the first coat fails to cover completely let it dry overnight and give it a second coat.  I didn't bake the primer, although many people do. 

  I quit here, the dark gray auto primer is dead flat, looks just like a steamer after a hard day on the road, a coat of coal soot everywhere.  It takes decals readily. 

 

  • Member since
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Posted by Southgate on Saturday, May 3, 2014 6:02 PM

What brand of primer are you using, David?  They vary greatly, and I've had some horrible results.  Do you have any pictures of your locos? I'd like to check 'em out. Dan

  • Member since
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Posted by mlehman on Saturday, May 3, 2014 8:21 PM

I built a PSC DL-535E kit about a year ago. Cleaned it up with mineral spirits, which helped get the rosin flux cleaned up. I washed it in TSP-substitute, then shot it before this pic with Rustoleum #2081 light gray wet sandable auto primer. Some sandable primers are pretty gritty, but this oen lays down fine just like non-sandable primers. Be sure you get that part #, as they also make the grittier stuff, too, and you don't want that.

Here's a pic of it primed and then finished.

Mike Lehman

Urbana, IL

  • Member since
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  • From: Central Absurdistan
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Posted by kbkchooch on Sunday, May 4, 2014 9:02 AM

Lots of good advice here, but allow a few thoughts based on my experience.

Ist in the cleaning department. 1st I give all the non-plastic parts a bath in either mineral spirits or laquer thinner to remove all the oils, then you can transfer all the parts to a white vinegar bath for light etching. From this point on, the parts are only handled with a gloved hand until the final sealcoat is applied.  Latex gloves are cheap insurance against a paint job ruined with a fingerprint.

Primer color selection is then done based on the top coat. Light primer for light engines, and dark primer for dark. This way if the topcoat sufferes a light scratch in service, it doesnt stick out like a sore thumb  Notice, I said light scratch. a hard scratch going to the brass is another animal.  Personally I try to stay away from rattle cans becuse of the general lack of control. Whenever possible, I prefer my airbrush. I've always hated rattle cans, even when I was doing bodywork on cars.

Also you can make paint holder jigs to support your models out of scrap 1x3 pieces. Use some scrap pieces of cork, cardboard or wrap tape around the wood to make a tight fit. Theis way boilers, tenders or complete diesel shells can be supported, rotated and moved without touching them. small parts can be held at the base with 2 sided tape. (see pic)

   

Take your time, make sure you have plenty of light, and you'lle be fine. 

Baking paint can be done, but I prefer to let it air harden 7-10 days (or until the paint smell goes away) before decaling and/or sealing.  Just in case I missed a plastic part and also to insure domestic tranquility Wink

Good luck! 

Karl

NCE über alles! Thumbs Up

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