Painting Large Plastic Nose Cones

[karlbaum]

The large plastic nose cones are made of polyethelyne and paint doesnt adhere well to it. I have even tried plastic primer. In the end the paint sometimes chips off after a flight. How do you keep the paint on your nosecone?

[troj]

First off, scrub it thoroughly in hot, soapy water -- dish soap will work fine. You need to get rid of the mold release.

After you do that, don't touch it with bare hands -- the oil from your skin inhibits adhesion.

Then, apply a plastic prep product according to the directions on the can.

Light sanding wont' hurt; do that before you scrub it.

-Kevin

[Pem Tech]

Actually both methods mentioned above, when used together, work quite well.
Here is what I do....
Scrub the little bugger with dish soap and water. Dry, then sand with 60 to 80 grit sand paper so you end up with a very rough surface on the cone. The lands and grooves really promote adhesion of the paint. Then prime and sand till you can't stands it no more.

[o1d_dude]

+1 to what the Retromaniac said.

The coarse grit sandpaper is critical as you want the primer to have some "fur" to adhere to. Oops...Sentence ended with a preposition....my bad.

[sodmeister]

Wash with alcohol
Wash with soap (dish)
Rinse with alcohol

NEVER...sand before washing anything ,you will just dig the release agent deeper into the plastic.

Sand (as others said)with a non-stearated sandpaprer (these have chemicals that lubricate the grit) 180 is a good start.

Prime with a good automotive primer (these are usually lacquer based or similar and bite better into the plastic)

Sand again with 220 -320 and wash down again with alcohol (after cured)

Re prime if needed

Then paint.

Works for me ,never really have had a chip problem to speak of.

Styrene plastic........well that`s a walk in the park.

Just my thought on the subject.

Paul

[James Duffy]

The large plastic nose cones are made of polyethelyne and paint doesnt adhere well to it. I have even tried plastic primer. In the end the paint sometimes chips off after a flight. How do you keep the paint on your nosecone?

I'll echo the comments made by everyone else in this thread, and add a couple of additional thoughts. In preparing for this past summer's World Spacemodeling Championships, those of us flying Bumper WAC models in scale altitude started with a V-2 airframe blowmolded from PET plastic. We found a Duplikolor product made specifically for this application:

http://www.duplicolor.com/products/adhesionPromoter/

The molding shop I worked with also suggested that paint and glue adhesion for PET could be significantly enhanced by flame-treating the part. I plan on trying that in the very near future; the process is said to be a simple as passing a handheld propane torch (set to the coolest possible temperature) over the part rapidly. A similar process is used to treat PET parts in the automotive industry, where it is called "corona treatment."

http://en.wikipedia.org/wiki/Corona_treatment

Another comment in this thread stated that styrene parts were much easier to paint, and I could not agree more enthusiastically. I had styrene test parts pulled from our molds just for grins, and while they were far too heavy for our scale altitude models, the parts were a breeze to paint.

Here's a photo of Tony and I with our models after static judging was complete:

http://www.rocketrylive.com/WSMC-201...e/IMG_9871.JPG

Here's a shot that shows the level of detail the blowmold process can produce:

http://tinyurl.com/2832g24

James
_______________________
James Duffy
jduffy@mac.com
www.rocket.aero

[sodmeister]

WOW ! Never seen such detail on a NC.

Good info ,thanks


Paul

[James Duffy]

WOW ! Never seen such detail on a NC.

That's not just the nose cone. I designed the blow mold to create the entire V-2 airframe. Injection molded bits are added for the warhead and exhaust nozzle, but the majority of the forward cone, all of the cylindrical section, and the aft cone are a single blow-molded component. Fins are injection molded parts as are an assortment of detail parts. Here's another detail shot, this time featuring the fins:

http://www.rocketrylive.com/WSMC-201...r%20detail.JPG

Hmm, maybe folks would want to buy one?

Perhaps, just perhaps.

Stay tuned...

James
___________________
James Duffy
jduffy@mac.com
www.rocket.aero

[sodmeister]

Yes i see now James ,very impressive !

And YES.....I think people want to buy one


Paul

[powderburner]

Hmm, maybe folks would want to buy one?

Please keep us posted on what sort of price you would be asking, schedule, etc.

Or start a separate thread where we can sign up on a waiting list---

[powderburner]

Someone just posted some good info recently here on TRF about this exact thing. They were recommending a special-purpose primer for this, I'll dig a little to try to find that thread.

Edit: Maybe this info will be helpful? Check out:
http://www.rocketryforum.com/showthread.php?t=14969
Lots of info on plastics, primers, and paints throughout that thread

[JDcluster]

You could try to use bumper primer / paint?

I just wash it, hit it with a propane torch, then sand it with 180-220 grit ( no finer) & finally prime then paint.




JD