Working with Brass Car Sides

[thomasjmdavis]

Tom D:  No, I don't bake the paint on the core kit, and wouldn't recommend trying it.  I paint the sides separately, bake them according to Scalecoat's recommendations, then glue them to the core.

All of my roads (BN etc) have the roof and ends a solid color, so matching the side stripes is easy - no match needed.  Just spray the core a solid color, and, if using Scalecoat, wait a week for it to dry.  For the BN black and GN "BSB" dark gray, I don't use Scalecoat, so those dry a lot quicker.

@nkalanaga- I apologize for being too cryptic in my remark, I have read enough of your comments here to know that you would not bake plastic parts. But I have known 2 people who (years ago) damaged models by baking them- one a composite model and the other a brass model that, as it turned out, had some plastic parts. 

I seem to be digging myself a hole here on this thread- I think I will get back to working on a couple of these and not talk so much.

[nickelplate759]

A different question - forming the skirts.
I've had unsatisfactory results from my attempts, and ruined a few sides, but I don't like the idea of leaving them flat. 

I like the idea of the bending jig Roberto Martari designed, but making one is beyond my skills. 

What works for you?

[nkalanaga]

Tom D:  Most of the articles I read, years ago, recommended baking Scalecoat at about 200F, which shouldn't be hot enough to damage styrene (see below).  If so, one COULD bake the finished car, carefully, but since the paint sticks very well to plastic, I've never tried it.  So, I took your comment as a warning to those who wanted to try it, just the way you intended it.  No apologies needed!

Another reason I bake them flat is that it's easier to letter the sides before they're glued to the core, and they have to be baked before lettering.

When I was building mine, I waited until we baked biscuits, or something, then turned the oven to its lowest setting, waited for it to cool off, and stuck the parts in.  I have no idea what the actual temperature was.

From Google:
"Thermoplastic materials become fully liquid at their melting point (210-249 degrees Celsius in the case of Polystyrene), but they begin to flow at their glass transition point (100 degress Celsius for PS)." 

So, 200F should be safe, but 212F might cause problems.  If you have an accurate thermometer, styrene CAN be baked.

[peteski]

Tom D:  Most of the articles I read, years ago, recommended baking Scalecoat at about 200F, which shouldn't be hot enough to damage styrene (see below).  If so, one COULD bake the finished car, carefully, but since the paint sticks very well to plastic, I've never tried it.  So, I took your comment as a warning to those who wanted to try it, just the way you intended it.  No apologies needed!

I wouldn't never put styrene nowhere near 200 deg. F.

Melting point is not the same as the temperature when the styrene softens up.  I've seen unassembled plastic model kits (in their original boxes) all warped after sitting in a hot attic for few years. And attic temperature doesn't get near 200 deg. F.  More like 130 or 150 on hot summer days.  I dry my painted plastic kits in a dehydrator which doesn't go above 120 degrees F.  I consider that safe.

[robert3985]

I wouldn't never put styrene nowhere near 200 deg. F.

Melting point is not the same as the temperature when the styrene softens up.  I've seen unassembled plastic model kits (in their original boxes) all warped after sitting in a hot attic for few years. And attic temperature doesn't get near 200 deg. F.  More like 130 or 150 on hot summer days.  I dry my painted plastic kits in a dehydrator which doesn't go above 120 degrees F.  I consider that safe.

+1

I've seen Micro Trains cars warp badly sitting in a hot car on a sunny day. I think the dehydrator is a great idea, and I'm considering getting one (or making one) just for the purpose of accelerating paint drying time for plastic models.

That said, I have cured plastic cars in my toaster with a precision thermometer in plain sight so I could remove the model quickly if the temp went over 135 deg F, because my little toaster oven doesn't have precision temperature control and the temperature sometimes fluctuates by 10 to 15 degrees at a low level. 15 degrees above 135 degrees can cause a plastic model to warp, sag or deform, especially if the model has thin portions, such as a passenger car or bridge (don't ask me how I know this!).

Nowadays, I just get patient, and paint plastic models with enamel over several days, letting them cure at room temperature between coats.

Cheerio!
Bob Gilmore

[hegstad1]

I use a hair dryer on plastic.  Works great and doesn't take as long as you'd think.

[nkalanaga]

Peteski:  You're probably right, even if styrene is supposed to be stable up to 212F/100C.  Even though it hasn't reached "flow" temperatures, it could still soften enough to relieve molding stresses, which is probably what caused the warping.

As I said, I've never tried to bake plastic, of any kind, to cure paint.  Scalecoat and Floquil stick very well to plastic, to the point of being almost impossible to remove, and acrylics probably shouldn't be baked at all.