How to paint plastic?

I'm working on my first model and I'm trying to paint it, but I'm not getting very good results.
I'm starting with an Atlas 706 station model. Actually, I'm starting
with one that I botched earlier but I'm using it for practice. In one of my books I saw it painted yellow with olive trim, which I thought looked nice, so I'm trying to paint mine that color scheme. I went to my local hobby store, selected "Depot Buff" and "Depot Olive" as colors that looked closest to what I saw and had appropriate names, and tried them out.
I'm finding that the Polly Scale paints are watery and don't have very good coverage, at least the way I'm doing it. Should I be preparing the plastic before painting on it? Most of the articles I've read about painting plastic models just gloss over preparation.
What about afterward? One book I have recommended spraying the structure with Dullcote after the structure is finished, but not to get it on any of the glazing. How is that accomplished?
Soon I will start a new Atlas 706 incorporating lessons I've learned from the old one. Maybe this time I'll be able to put that *%@*!* telephone booth together without breaking it. :-)
Robert
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Robert, You should wash the plastic with warm soapy water and let it air dry. Then don't touch the areas you want to paint with bare hands. The reason is that there are mold releasing agents on the plastic and oils on your fingers. As to the paints, are you stirring them enough. I usually put a BB or a small nut in each bottle to act as an agitator when I shake the bottle.
Are you using a brush or an airbrush?
If the bottom is open, as most are, you can add the windows after you dull coat it. Otherwise, paint decal and dullcoat the parts then add windows and then assemble it.

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Frank Rosenbaum wrote:

That might be my problem. I'll try washing the pieces of my new model and see if it improves the way they take paint.

I think I'm stirring them enough. At least, I'm giving them a good shake and then stirring them with a stick, and everything looks uniform.

I'm using a regular brush. I've never airbrushed before and I don't want to introduce too many new concepts at once.

This particular model has window frames that the glazing attaches to, and then the window frame goes into the wall. I don't know how well glazing the window after the frame has been put into the wall would go.
Given that I'm painting most of the visible structure anyway, I think I'll forego the dullcote for now.
Robert
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Robert wrote: [...]

Yes, you must wash the mold-release agent off the plastic parts. I do this before assembly, but if you have assembled the model, just squoosh a dollop of plain, unscented dishwashing liquid in the sink, add warm water, and slosh the model around in it. If the water beads up, use a soft brush to help remove the release agent.
That usually works, Sometimes, it's useful to give the parts/model a _light_ overspray of red or grey automotive primer. This provides "tooth" for the paint.
Then you can apply washes or full strength paint, as desired.
Note that light colours, espcially yellows, do not cover very well, Apply two or more light coats rather than one heavy coat to get the best coverage.

Well, you do all the painting before applying the glazing. :-) O'wise, use blue or green painter's masking tape to cover the glazing.
If you use flat paints, you won't need Dullcote. It actually has very limited usefulness in my experience. I've occasionally used it to provide a uniformly flat coat after decalling and weatherng a car, but that's about all it's good for.

Tip 1: gently file all mating edges to get rid of flash, and test fit parts before gluing.
Tip 2: do as much painting as possible while small parts are still on the sprue. After removing from the sprue, file or sand off paint where it's not wanted. Touch up after assembly as needed.
Tip 3: emery boards sold for polishing nails are excellent tools for filing/sanding parts to size.
HTH
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Wolf Kirchmeir wrote:

I think I read somewhere a recommendation to spray dullcote over the whole structure after it is assembled, to blend the colors together. I don't think I'm nimble enough to glaze the windows after the rest of the structure has been assembled. I think I'll skip the dullcote this time around. :-)

I have a set of metal files I was using to remove flash, but it turned out to be too much for one of the phone booth pieces, which broke.
Robert
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One thing that I have noticed with many models, is that even when they have been "road weathered" they still have a slight shine or gleen to them, & I understand this is a result of dull cote bein used.
Wash the parts in light warm soapy water as others have said. Allow to thoroughly dry. At this point use a spray can of grey primer on the model, cover the glaze areas with "Micromask" this just peels off later. & then go with flat acrylics.
Another method, is to try using a scratch brush on the surface first. I have used this to take the shine off several models, especially brake vans. By itself it leaves a realistic dull colour to the model & only a light covering of paint is required if its a weathered model. DO NOT use a scratch brush if you want a model that is to look pristine
As you have found, files are at times not very forgiving, if filing a smal item, mask it up to the edges with tape to give it some strength, or use the edge of fine craft knife. Here in OZ we can them in a blue plastic pack with three different sized handles & about 20 spare blades for $2.00. Try the dolloar shops, the same product in hobby shops often cost over 4 time th price
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Wolf Kirchmeir wrote:

I just washed a couple of my sprues with Ivory dish soap, using a toothbrush to work each piece and rinsing them off as thoroughly as I could.
Is there a way I can tell I got the mold-release agent off? The plastic looks and feels the same to me, and I don't want to start painting only to find I didn't do a good enough job cleaning the plastic.
Thanks,
Robert
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Robert wrote:

Try a dab of paint on the sprue. If it sticks, good. If it beads up, not so good.
The mold release agent isn't visible. You might notice its absence by feel, but you might not. Styrene plastic for models is filled with additives that make it softer, which also tends to make it slippery to the touch.
HTH
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Okay. I was a bit concerned when I didn't seem to be seeing anything washing off of the plastic, but I painted one of the sprues last night and it looks okay. It's a little uneven and it will need another coat, but it's looking much better than my previous attempts.
My concern at this point is that some of the paint got into places I will need to apply plastic cement to. I think there is still enough exposed plastic to give a good hold, but I may need an extremely fine tool capable of scraping off paint without harming the plastic underneath. Maybe the file on my nail clippers will work.
Thanks for all your help!
Robert
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You can scrape the paint off the areas to be joined with an Xacto knife, or other type of blade. Just scrape gently and the paint will come off.

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Robert wrote:

Look for a set of "needle files" at Canadian Tire (if you're lucky to live up here), or Home Depot, Radio Shack, etc.
HTH
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On Mon, 12 Dec 2005 17:00:19 -0800, Robert wrote:

Note that if you "feel" it, you're replacing the mold release stuff with oil from your skin. Not a good idea.
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Robert wrote:

As others have pointed out, surface preparation is key. Hot soapy water is required to get finger prints and mold parting compound off the plastic parts. For real cleaning power use a laundry detergent like Tide. The laundry (washing machine) detergents contain a good deal of tri sodium phospate (TSP) which is a good grease cutter, and in strong solution can even remove water based paint. The dishwashing liquids lack the TSP but are often strong enough. Rinse well in clean water to prevent detergent residues from spoiling the paint coat. Then you usually need to prime the surface. Paint doesn't "cover" all that well. For instance, if the underlying plastic is green, a coat of red modelers paint won't "cover" the green in one coat, perhaps not in two. Unless the plastic is close to the finish color, you want to prime the surface with "auto primer". These are spray cans available from your local auto parts store, that come in red, dark gray, and light gray. Use red primer under red, light gray under light colors like yellow, and dark gray under dark colors like blue. The primers stick well, cover like crazy, and are dead flat and offer good "tooth" for the finish coats. Gray is a neutral color which is easier for the finish coats to "cover". After priming, you can paint with either a brush or a spray can. The brush marks will level out if you lay down enough paint to wet the surface and don't go back and add a second coat before the first one is dry. Spray cans don't leave brush marks, and with practice you can lay down a uniform coat that doesn't run. Most spray cans are gloss paint, for model railroad work we usually want a flat finish. I have only found flat black, flat white, and flat olive drab (aka Pullman green) and the auto primers (red, light and dark gray) for flat spray paint colors. For brush painting, check out the craft stores which often carry a nice flat water base paint in a wide range of colors. Big John Dalton swore by the craft store paint. He claimed it cost less, covered better, and come in all sorts of colors. I have a jar of flat craft store white that covered handrails well. If you use a gloss spray can color, you can flatten the glossy surface with Dull Cote. Dull Cote is a clear finish with enough talcum powder in it to make it flat. It is also essential to blend in decals. One coat of Dull Cote blends the decals into the paint and makes them look realy good. Without Dull Cote, you can see the sheen of the decal backing. If no decals, and a flat finish, like say red auto primer, you don't need Dull Cote at all. Incidently, the red auto primer is a good brick red and a good boxcar red, just as it comes out of the spray can. Auto parts stores often carry "touch up" paint to match every paint ever used by Detroit, which gives you quite a bit of latitude in color choice. All of them are gloss, but the Dull Cote will flatten them out nicely. One other caveat with the use of Dull Cote. Dull Cote "marries" into chalk weathering. If you weather the structure with chalk, Dull cote will make the chalk just disappear. In practice, this means I can use chalk to weather structures that don't geet handled all that much, but I cannot use chalk on rolling stock, cause handling the car rubs it off, and Dull Coteing the car makes it go away.
David Starr
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I've been painting plastic model buildings and aircraft for yonks and have never washed any of the plastic bits. Enamel and acrylic paints used, brush applied, no troubles with paint not adhering or rubbing off. Regards, Bill.

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On Thu, 15 Dec 2005 19:24:49 +1100, "William Pearce"

    Quick, buy a lottery ticket as you are the luckiest person I have ever met. I have had problems with about 10% or plastic models before I started washing them. Since washing zero problems. EVERY plastic molder uses some form of mold release, some more than others but even a small amount can cause trouble.. Sooner or later everyone's luck runs out.
                                cat
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cat spake thus:

Dunno about that; I've also never washed any plastic I've painted, and have never had problems with paint adhesion.
Seconding an emotion expressed above in this thread, I like to paint with a flat solvent-based primer (spray can, Floquil or similar) paint, then use acrylics (water-based) over the primer, either brushed or sprayed. Acrylic paint doesn't stick very well to raw plastic.
I don't think you need to worry so much about painting. Experiment on some scrap, then just go for it.
--
God willing, the many crimes of the Bush Administration
will eventually be printed in a nice leatherbound,
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