To see the pinholes, start with a light coat of primer. They show right up.
Next, the boot cowl, engine cowl, nose bowl, doors and windows, and the windshield frame pieces must be painted.
Fiberglass pieces like the nose bowl present a special challenge. They
always come with a bunch of tiny little pin holes that are sometimes a challenge
to fill. These pin holes are hard to photograph but if you look close, you
can see them here on the nose bowl:
To see the pinholes, start with a light coat of primer. They show right
up.
These cannot be filled with just primer. The primer tends to just bridge
across the hole and when you sand it, the holes show again. You must
have a way to fill the pinholes. My solution was glazing putty found
at any auto parts store or auto paint supply store. The glazing putty
must be pressed in firmly with a rubber squeegee to fill the pinholes
completely:
This stuff dries in about 10 minutes and can be sanded. Block sand
the piece with some dry 180 grit sandpaper. Here is what it looks like
after sanding:
As you can see, the putty has filled the pinholes.
Another coat of primer revealed just a few more pinholes which were filled with some more glazing putty. The nose bowl was then primed with a filler/primer and after drying, it was wet sanded smooth with some 360 sandpaper.
I have a very low-tech set up for priming all of the pieces. The airplane
was pushed outside to prevent overspray from getting on it and the pieces
were all hung from wires in the shop:
The pieces were scuffed with some scotchbrite pads and wiped down thoroughly
with Naptha using one towel to wipe it on and a dry towel to wipe it off.
For these pieces, I didn't use the typical acid etch/alodine treatment
like I did for the critical pieces like the wing spars.
These pieces were primed with a couple of good coats of EP420 Epoxy Primer and allowed to dry for 1 week.
As previously discussed, I chose Poly Tone for the fabric portions of the airplane fuselage. I have now decided to also use the Poly-Tone for the doors, boot cowl and engine cowl on the Fuselage. My decision to stick with the Poly Tone for the aluminum on the fuselage, is based on my discussions with several people. As the Poly-Tone on the fabric fades a bit over the years, it will take on a different look than enamel used on the doors and cowl.. In several years, I would have an airplane that looks like a patch-work quilt.
Since the wings do not come in direct contact with the same color of fabric on the fuselage, I'll go with the Poly Fiber Enamel with hardener on the wings for durability.
I have heard a lot of horror stories that the Poly Tone does not stick well to metal parts. However, the Poly Fiber experts have outlined a technique (see the manual) for improving your chances of success and I have heard from a few people that have tried it, that works well and has held up over time.
Here is the process for using Poly Tone on aluminum:
1. Prepare and prime the aluminum as usual with White 2 part Epoxy Primer
(EP420 with catalyst).
2. Let the primer cure for at least a week.
3. Now for the tricky part. Prepare two paint guns; One paint gun with some White 2 part Epoxy Primer (EP420 with catalyst) and one paint gun with some White Poly Tone.
4. Go over the primed parts with some fine scotchbrite pads and then wipe them down with Poly Fiber's Paint Surface Cleaner (C-2210)
5. Using the paint gun with the Epoxy Primer, spray on one good medium coat of the primer.
6. Quickly switch over to the paint gun with the Poly Tone and while the primer is still tacky, spray on one full coat of the white Poly Tone.
7. Let this cure for another 7 days.
What happens is the Poly Tone interacts with the Epoxy Primer and adheres to the aluminum real well. After it cures for a week, you can spray on more coats of the Poly Tone as per the instructions in the book and they will interact with the Poly Tone in the Epoxy.
Back to painting the fuselage:
Once I had the single coat of Poly Tone/Epoxy Primer as outlined above and
it had cured for one week, I went ahead and assembled the doors, boot cowl
and engine cowling on the fuselage. I then masked off the top half
(from the top of the upper white stripe) and put two more good cross coats
of the Poly Tone White on the doors, boot cowl and engine
cowl:
That was allowed to dry for a day and a half and then the stripes and bottom
half were masked off in readiness for the Red Poly Tone. Careful attention
was paid to making sure the stripes matched up perfectly with the existing
stripes on the fabric part of the
fuselage:
Of course the cargo doors were masked for striping as
well:
Everything not masked off will now be sprayed with Pontiac Red Poly Tone.
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