Spray Painting different materials - Novice level

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ChrisGreaves
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Spray Painting different materials - Novice level

Post by ChrisGreaves »

Forum?
Once winter comes I shall be back on the funicular; in the meantime, the wind turbine, so not modelling railways, but playing with aerosol cans of paint. "Getting ready to get back to the model railway", I might say.
20210920_113647.jpg
Yesterday afternoon I spray-painted (a can, remember) the plastic nose cone and the metal collar of a two-foot wind turbine, experimenting before tackling the turbine body and the three vanes.

The white plastic nose cone looks good at the tip, but the bulk of it is speckled, or patchy perhaps. It looks as if the paint went on OK, but then contracted, as do clay pans as the lake bed dries up. But what do I know?
The painted (enameled?) metal collar looks good on the main part, but the narrow part has the same appearance as the bulk of the nose cone. But what do I know, again.

Of course I have now run out of small discreet pieces on which to experiment, but I am optimistic that experienced spray painters here will be able to suggest something that I might be doing wrong.
(1) Holding the button down for too long (too thick a coat)
(2) Trying to cover in one coat/session rather than two or three
(3) Wrong kind of paint (i.e. don’t just grab any old can from the shelf at the hardware store)
(4) Need different paint types for white plastic versus painted metal
(5) Holding the can too close to the parts
And so on.

Why am I painting the wind turbine green? Because I don’t want to have an aeroplane-brilliant white object sitting atop my shed; I’d rather it blended into the trees in the background.

Thank you for any anticipated tips or suggestions
Chris Greaves
Bigmet
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Re: Spray Painting different materials - Novice level

Post by Bigmet »

Coverage appears best on surfaces that are 'topside' on both pieces in the photograph, the nearer vertical locations have poorer coverage.

If the paint is adhering well, why worry? Other than such as snow and sky, nature rarely produces large monochrome areas; variegation will appear more natural, and everything on the moving parts of the turbine will be a blur when spinning...
ChrisGreaves
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Re: Spray Painting different materials - Novice level

Post by ChrisGreaves »

Bigmet wrote:If the paint is adhering well, why worry? Other than such as snow and sky, nature rarely produces large monochrome areas; variegation will appear more natural, and everything on the moving parts of the turbine will be a blur when spinning...
BigMet, thank you for this perspective. Indeed, when things are moving the "dotty" painting won't show, and most of the time folks will be walking/driving along the street, some fifty feet away.
Now I think about it, a larger-scale "blotchy" effect would not have hurt; something along the lines of the wavy patterns on battle-ships to break up the stark horizontal lines.
Thanks again
Chris
abenn
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Re: Spray Painting different materials - Novice level

Post by abenn »

Maybe a bit late now, but here's my take on it in case someone else has the same problem.

Whenever I paint any kind of plastic, including glass and carbon fibre, I prime it first with Halfords plastic primer. In my experience this provides a good key for enamels (e.g. Humbrol), water-based acrylics, and Halfords own car paints. It's probably good for others, but that's all I have experience of.

Note that some solvent-based paints can react with some plastics and make them crazed and/or brittle.
ChrisGreaves
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Re: Spray Painting different materials - Novice level

Post by ChrisGreaves »

abenn wrote:Maybe a bit late now, but here's my take on it in case someone else has the same problem....
Abenn, thanks for this. All data is grist to this brain (grin!), and a delay is not a big deal. Every bit of material for modelling has to be ordered in where I live, and the order has to be preceded by enquiry, discussion etc.
Thanks again.
Chris
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Bufferstop
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Re: Spray Painting different materials - Novice level

Post by Bufferstop »

I've been using grey acrylic primer from Hobbycraft. Preparation for plastics, metal and other impermeable surfaces is a scrub in a litre of hot water with a dishwashing tablet dissolved in it. Then I spray from the rattle can, avoiding getting close enough to appear wet. It's ready for spray painting after 30 to 40 minutes. For priming the rattle can seems best, I save the airbrush for the more detail work.
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