lotus



previous page: 6.5 Rocketry: Are there any good tips when making my own nose cones?
  
page up: Model Rockets FAQ
  
next page: 6.7 Rocketry: Is it possible to get a high gloss, durable finish on a model rocket?

6.6 Rocketry: Getting Paint to Stick to LOC and Aerotech Nose Cones




Description

This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.

6.6 Rocketry: Getting Paint to Stick to LOC and Aerotech Nose Cones

From: kwolfe@interramp.com (Ken Wolfe)
VERY VERY important......WASH THE PLASTIC FIRST!
I had this problem until I started to wash the plastic before even
assembling anything. This solved most of the problems I was having.

From: Roger.Wilfong@umich.edu (Roger Wilfong)
I have had success painting nose cones from both companies using Krylon
and Walmart paints. The technique I use is to wash the nose cone with
a Brillo pad followed by a thorough rinse. Fill the mold parting mark
with auto body putty and sand it smooth. I next use a coat of primer
(I've used Krylon's grey sandable, Walmart's grey and Black Baron - the
Black Baron was the best, but also the most expensive and took the
longest to cure). This is followed by a light sanding and another
coat of primer, followed by sanding. After the primer cures (a week, if
I'm in the mood to paint, a year if I'm not), paint it with some paint
that's compatible with the primer.

This technique works fine on the LOC nose cones, the only problem I've
had with the Aerotech nose cones is that the very tip tends to get
chipped off.

I have a LOC PNC-3.00 that has lawn darted into hard ground twice. The
original paint is scratched, but it shows no signs of flaking off.

From: smith@mrcnext.cso.uiuc.edu (Greg Smith)
I rough up the surface of plastic nose cones with 60 grit paper, then
use my basic epoxy painting regimen as I've described earlier. After
the first coat of primer, the surface is *really* fuzzy; the paint
reinforces and thickens all the little plastic strands that are raised
by the sandpaper, and the surface feels like rough concrete. But a
little sanding knocks off most of it, and after the third primer coat or
so, the surface is as smooth as anything else on the model.

The only time I've ever damaged the finish on one of these nose cones
happened when a model fell off the workbench and onto the concrete floor
in my basement, which chipped the tip of the cone a bit. Normal flying
(including one or two landings on concrete) hasn't affected them at all.

From: jsvrc@rc.rit.edu (J A Stephen Viggiano)
As I have said repeatedely, the most effective way to paint on these
plastics is to introduce carboxyl groups at their surfaces. This will
give the paints something onto which they can grab.

A carboxyl group, also known as a fatty acid group, consists of a
carbon atom, to which an atom of oxygen is doubly bonded, and also
a hydroxyl group is bonded. In order to convert the end of a polymer
chain into a carboxyl group, you need to provide oxygen and some
energy. The oxygen may, of course, come from the atmosphere.

In the packaging industry, when polypropylene and polyethylene must be
printed, they are given either a "corona discharge treatment," in which
the surface is passed beneath a high-potential device called a coratron,
or a "flame treatment," in which a gas flame is allowed to impinge
on the surface for an instant. For historic reasons, the second treatment
may be referred to as a "corona treatment," even though no corona
discharge is involved.

I've used the gas flame from my kitchen range with excellent results.
Don't overdo it, for obvious reasons. Only an instantaneous contact
with the flame is needed.

Since using this treatment, I have had virtually no problems with paint
flaking from my polypropylene nose cones.

From: preddym@ucs.orst.edu (M Preddy)
I've had good luck with Rustoleum primer on LOC nosecones. Krylon
sticks to it fine.

From: kaplowro@hccompare.com (Bob Kaplow)
Consider covering nose cones with econo-kote.

 

Continue to:















TOP
previous page: 6.5 Rocketry: Are there any good tips when making my own nose cones?
  
page up: Model Rockets FAQ
  
next page: 6.7 Rocketry: Is it possible to get a high gloss, durable finish on a model rocket?