Does brass require any special prep prior to painting or "take" one type of paint (e.g., water- or oil-based) better than another? I've never used brass before and am expecting delivery of Tomar's Hayes bumpers soon. If yes on either or both counts, details appreciated.
Thanks.
Kerry
brass does tend to hold -better- with two added steps ...
first is an etch or pickle to slightly roughen the surface, even just a few minutes in warm ordinary vinegar, and
secondly, it does hold a little better with an enamel or oil based paint
Paint has trouble sticking to metal. You need to give the paint all the help you can. The metal needs to be free of oil and grease, mold parting compound, any and all sorts of crud, and finger prints. Hot water and soap, scrub with an old toothbrush, followed with a good rinse, followed with a total dry. Overnight. Once washed, don't handle it with your bare hands, that adds fingerprints.
Then you want to etch the metal by soaking it in acid. I use supermarket vinegar. Soak for maybe an hour. The etch gives some tooth to the surface for the paint to latch on to. Wash and rinse thoroughly to get the acid off, lest it do bad things to the paint.
Make your first coat a primer coat. Krylon and Rustoleum make "auto primer" in rattlecans, three colors, dark gray, light gray, and red. The auto primers have the best stick-to-metal chemistry known to man. They dry dead flat and make a fine surface for any top coat you may please, solvent based or water based. Use dark gray under dark colors, light gray under light colors and red under red. The red makes an excellent box car red. The dark gray is a fine steam engine color.
David Starr www.newsnorthwoods.blogspot.com
wvg_ca brass does tend to hold -better- with two added steps ... first is an etch or pickle to slightly roughen the surface, even just a few minutes in warm ordinary vinegar, and secondly, it does hold a little better with an enamel or oil based paint
dstarr Paint has trouble sticking to metal. You need to give the paint all the help you can. The metal needs to be free of oil and grease, mold parting compound, any and all sorts of crud, and finger prints. Hot water and soap, scrub with an old toothbrush, followed with a good rinse, followed with a total dry. Overnight. Once washed, don't handle it with your bare hands, that adds fingerprints. Then you want to etch the metal by soaking it in acid. I use supermarket vinegar. Soak for maybe an hour. The etch gives some tooth to the surface for the paint to latch on to. Wash and rinse thoroughly to get the acid off, lest it do bad things to the paint. Make your first coat a primer coat. Krylon and Rustoleum make "auto primer" in rattlecans, three colors, dark gray, light gray, and red. The auto primers have the best stick-to-metal chemistry known to man. They dry dead flat and make a fine surface for any top coat you may please, solvent based or water based. Use dark gray under dark colors, light gray under light colors and red under red. The red makes an excellent box car red. The dark gray is a fine steam engine color.
When I paint brass, first step is a complete tear down, as insulated wheels and the motor/wires need to set aside. Then the vinagar bath for the various parts, followed by a trip thru the dishwasher. Once dry(usually the next day or so), I air brush them with my chosen paint In my case, I use Badger's Modelflex acrylic as it bothers my asthma the least. Clean up is a snap with no nasty chemicals or thinners, Just water to thin and Isopropal Alcohol (rubbing alcohol) to flush my brush out. Been painting brass for many years this way with great results. Once the model is painted, it goes in my oven for 60min at 175'F to cure the paint. Once cooled back down, you can remask and spray the next color. Any light colors, like white, red, yellow ect. Need a light grey primer to look thier best. Pictured below is a Suydam/Orion Models Pacific Electric 1360 Combine. I used the sand roof color as both the roof color and a base primer for the red body. Pic is taken in my oven right before I took the model out to cool. I will let the body air cure for a few more days before I decal and seal them with Testors Glosscote, or Dullcote depending on the finish I desire. Mike the Aspie
Here is another Suydam/Orion Models PE car, this time a Long Beach Twelve I painted last year.
Silly NT's, I have Asperger's Syndrome
If the brass piece is covered with old paint or is oxidized, I use a hobby blaster to make it shine again, using soda as the blasting material. For steam locos, I will also dissassemble the boiler to bake the primer on for about 20 minutes. Other components can be primed by hand - dilluted shellac works well for that. I agree, acrylics work fine, as long at you use the proper primer, such as a good quality auto primer. Here is one of my favorite locos that received the above treatment:
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Simon
If you will solder these up (never had any Tomar's so not sure if or not) then you first need to clean things up from any flux used. I used rosin-core solder plus additional rosin flux as needed when building my PSC DL-535E kits of the "big" WP&Y diesels. Got 91% alcohol (or denatured alcohol) enough to cover the entire assembled model and any related pieces and let it sit, then scrub it with a toothbrush and rinse well.
Generally, you don't want to use acid flux around model railroad applications, but there may be other that can be used besides rosin flux that you find acceptable. In any case, follow the directions for cleaning it up because something other than alcohol may be needed.
Nice and shiny is where things end up, with the bare second model sitting next to the painted first-built.
It was ugly before, looked like someone smeared it with someyhing to vandalize it if it was 1:1. It was just the result of the rosin getting all over things with the various reheats of building a model. I tried to find a pic of it all nasty, but guess I didn't want such embrassing pics out there so didn't save any. This is all about general cleaning up after significant soldering work, either building or modifying a brass model.
After that is a good time to give it some "tooth" with vinegar or other etchant and take the rest of whichever path in paint prep you choose.
Mike Lehman
Urbana, IL