Spray paint

[Gilson78]

Does climate affect painting rockets. I was spray painting a mach buster and it
was cold and damp and it dried in horrable clumps.

[MODROCKET]

>Does climate affect painting rockets. I was spray painting a mach buster and
>it
>was cold and damp and it dried in horrable clumps.
>

Yes! Humidity is the painter's and rocketeer's enemy. My experience has shown
that the lower the humidity the better. If I can get 30 -50% humidity in South
Louisiana I go for my can of krylon, because it doesn't get any better than
this.

Practically, humidity effects the gloss of the paint finish. High humidity and
temperature makes the finish cloudy and dull no matter how many coats you put
on.

My advice is that it is best to wait for the right day and get the paint job
that you really will like. I just set my primed rocket aside and go start
another one! It is a good exuse to go buy another rocket!

Everything that I have said relates to outdoor painting which is all I do. You
can go the paint booth route or someother indoor operation and have more
control over the humidity and temperature variables.

Good Luck
Joe A.

[Mark Simpson]

Using a solvent-borne paint in a humid environment isn't good. As the solvent
evaporates, it cools the rocket and allows water droplets to condense on the tube,
just like moisture condenses on the outside of a glass of cold liquid on a hot day.
. Since most solvent-borne paints aren't miscible in water, it creates a problem
with the paint film. At best, you wind up with a dull finish, at worst, the paint
film cracks, spiderwebs and isn't adherent. That's why auto companies pay hundreds
of million of dollars for sophisticated humidity/temperature-controlled painting
booths and paint curing ovens.

Mark Simpson
NAR 71503 Level II

[Rocket9005]

And if the temp is too low the paint takes for ever to dry, and you get lots of
runs in the finish.

[Jay Goemmer]

In article <20001229204710...@ng-cm1.aol.com>,
modr...@aol.com (MODROCKET) wrote:

> > Does climate affect painting rockets. I was spray painting a mach
> > buster and it was cold and damp and it dried in horrable clumps.
> >
>
> Yes! Humidity is the painter's and rocketeer's enemy. My experience
> has shown that the lower the humidity the better. If I can get 30 -
> 50% humidity in South Louisiana I go for my can of krylon, because
> it doesn't get any better than this.
>
> Practically, humidity effects the gloss of the paint finish. High
> humidity and temperature makes the finish cloudy and dull no matter
> how many coats you put on.

Hmmm... An unexpected advantage of living in a high desert climate
like Southern Idaho. Humidity is relatively low most of the time.

I could try to get specific percentages, but our station's
weatherman just moved out of town.

Cheers,

--Jay Goemmer
"Centuri Guy"
Twin Falls, ID

http://www.kmvt.com/newsstaff.htm

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[Larry W. Hardin]

High humidity can lead to trapping water droplets in the paint which will give
a dull milky looking finish. Sometimes you can spray another coat in really
dry conditions and get rid of the trapped water.

Temperature can affect the droplet size that comes from a spray can or
airbrush. The paint thickens up at low temperature and splatters. Running
warm water over the can helps to thin the paint and increase the pressure
which gives a better result.

[Mark Simpson]

Larry,
High humidity doesn't lead to "trapping water droplets", it leads to the creation of
water droplets on the surface as the solvent evaporation cools the painted surface.
Just like rubbing alcohol cools your skin as it evaporates, volatile paint solvents
can cool a rocket appreciably, causing the rocket surface to cool to below the local
atmospheric dew point and voila, you have a wet surface that is incompatible with the
solvent-borne paint that you just sprayed.
Most rattle cans warn about painting in cold temperatures for just the reason that
you stated, it's viscosity increases and it becomes more difficult to atomize.

Mark Simpson
NAR 71503 Level II