Paint
On this page I plan on documenting anything and everything that is related to painting the interior and exterior of the plane.
Cockpit
For the interior, I decided to keep things simple by using rattle cans instead of an HVLP gun. I ended up choosing Rustoleum Hammered light gray because it should hide flakes and scratches well. Another benefit of using somple rattle cans is that you can tough scrathces up with very little effort. It took about 4.5 cans to cover everything.
Exterior Paint
For the exterior primer and topcoat I chose Stewart Systems single part primer and waterbourne two part poly. Air will be provided by the Axis Citation 4 stage turbine and Accuspray 10G HVLP gun with 726 cap and 1.3mm tip. A local 9A builder was kind enough to lend me his turbine and gun setup. Without it I would have had to purchase a larger compressor as well as run 30 amp service out to my garage. I chose Stewart Systems because of its easy cleanup and non cancer causing fumes.
Paint Booth
The first step was to construct a paintbooth that could evacuate overspray and supply fresh clean air. I sectioned off half of my garage and lined it with 3 mil plastic and screwed small hooks into the ceiling that will later be used as hangars. Three cheap Home Depot supply fans supply air through three HVAC filters, while a single fan removes air. I adjusted the speeds of the fans so that the booth is only slightly pressurized. For about $80 bucks it works really well - Dexter would be proud.
Cleaning and Etch
A successful paint job begins with careful and meticulous prep work. The SS process is fairly simple in that it only requires their cleaner, etcher, clean water, terry towels, scotch bright pads, and a hose. First you clean the surface with their heavy duty cleaner and a terry towel. Next you rinse the surface, spray with etch, let sit for 5 minutes, scuff the surface with scotch bright or 320 grit, and rinse. I followed up with another clean rinse and terry towel scrub in an attempt to remove any aluminum particles that were left behind. Fiberglass parts are prepared the same way minus the etch. The clean and wet parts were then hung in the paint booth overnight to dry.
1.5mm Tip vs 1.3mm Tip
HVLP spray guns can be configured to spray different viscosity paints by simply swapping out the tip or the cap. The tip is the stainless steel part through which the paint sprays and the cap is a large aluminum part through which the air is directed and forced into various fan patterns. If your tip diameter is too large the paint will flow out faster than the air can atomize it. This becomes a real concern when your paint is thin or your air source is weak. I started with a 1.5mm tip and found the paint was not atomizing very well. The 1.3 helped, but a higher pressure air source would have been the ultimate solution.
Fiberglass Primer
Fiberglass parts are primed in a charcoal grey primer. This stuff was very easy to shoot and sanded easily.
Aluminum Primer
The aluminum primer was harder to shoot that the fiberglass primer because it wanted to run or form fisheyes if it was spayed too thick or in humid weather. I thinned both primers with 10-15% water and had good results towards the end. The primer was sanded with scotchbright or 320 open coat depending on how flat it dried.
Topcoat
The topcoat was not easy.
The trick is laying down a nice light tack coat before subsequent heavier coats. Too heavy too soon = fisheyes and runs. I thin to 10%+- 1%.
Lesson #1:
Dont get it on your skin! I got some paint on the back of my glove then accidentally scratched an itch on my neck. It felt like a moderate case of poison ivy for 8 days.
Lesson #2
Try all colors on a spare part first! I practiced with my primary base color smoke gray on scrap parts until I had decent results then decided to shoot lemon yellow on my elevators. Of course the finish looked great, but the color was terrible! Sand, prime, try again with new color scheme.
Lesson #3
Dont spray it on too thick! Round 2 on the elevators and I decide to lay the last coat on thick. They looked great, everything flowed out nicely with no runs, it was my best work. The next day I went out and found a flat dull texture. It was a mild case of solvent pop or blushing. Basically, the solvent couldnt find its way out of the paint before the top skinned over. What youre left with is a cloudy soft matte finish that must be stripped off.
Lesson #4
Dont spray when the dewpoint temp is within 10 degrees of OAT or when humidity is above 65%. The paint simply wont flash between coats causing runs, sags, pigment anomalies, etc. I screwed up my right flaps twice before I figured this out.
Lesson #5
Luck. One day I wasted 200 grams of topcoat because my $60 gram scale decided to jump from 39 grams of catalyst to 70 grams in half a second. I didnt know how much I mixed in so I scrapped the batch. Then, after remixing and shooting 3 nice coats, my gun did something I've never seen before. It started shooting strings and blobs of paint on the canopy skirt. Im thinking the pot life was reduced due to the elevated material temps - ill be sure to store the paint in my AC'd house from now on. More sanding...
In the end it turned out pretty nice. I decided to overlay some of the plans onto the skin to give it a CAD drawing look. It surely wont get lost in the crowd.
