Painting Wings

Preparation

With the wings off to fit the tanks and tidy up all those small details and the decision was made to paint the underside of both in Duck Egg Green. The first task was to remove the fibreglass tops and mask up the wheel well, tips and other items requiring protection.

The wing was moved under a 6 x 3-meter gazebo, with the sides closed the wing, next, a thorough check as made and all those overclocked tasks were resolved and finally, the whole service was cleaned using water/detergent and 3M Ultra Fine sanding Pads and dried with paper towels. Both undersides were wiped using lint-free towels with wax and grease remover and wiped with the same then finally with a tack cloth.

Four [4] small blowers were mounted onto a work table to help extract fumes and overspray, it was decided to use smaller blowers as if a large set of fans were used it would mean lots of air coming in creating the need for filters.

An Apolo 5 stage turbine sprayer was selected for a number of reasons,

The first one being as I am 100% dependent on solar and thus have limited power for a large compressor. Another reason was they produce very little overspray due to the low pressures used and they warm the air helping to dry it for spraying. A  full-face mask was purchased to spray all the 2K products along with a mask/filter for the undercoats and base.

Personal Up Skilling

The internet is a good source of information but it has to be filtered, listed below were two key pieces of information that helped me make a decision to pull the trigger. Many hours were spent looking and absorbing as much information but end the end its spraying that is the final judge of all the effort.

2k paints are thinner than water, the first coat is a 'dust coat' - it means just that, dust the paint on, do not attempt to cover the whole surface with paint with the gun. Since the paint is so thin, it will spread and evenly cover the surface. For the second coat, lay it on a tiny bit thicker. It is difficult to see how thick you're putting it on though. You'll find after the dust coat has had a few minutes to settle on the panel, it will form a solid colour and the dust effect will go away. This will now give you more surface area to cover with the second coat, hence needing more paint.

[The comment above was extracted from a painting forum and proved to be of great value]

Jake LeStrada "No Fool Zone"  was a personal mine of information on using an HVLP and was the final link to give me the courage to pull the trigger.

Painting

Concept Paints 103 etch primer was thinned 1:1 using approved thinners, strained into the paint pot and after test applications on paper was ready to apply to the wing. A light coat was applied. Next,, the whole area was scuffed with a 3M Ultra Fine Sanding Pads using water with detergent, this didn't remove the paint from the rivets like 600 grit would have thought it was used in some areas. Once done the final feel was smooth so the next step was to proceed with applying base colour.

No high build primer was applied to save weight - my gamble.

Once ready the Duck Egg Green basecoat was mixed 1: 1 using thinners supplied, strained into the paint pot and after test applications onto paper the first coat was applied. Though it looked OK there was a lot of orange peel and this was traced to operator error, to fix this, it was sanded over an afternoon.

With the next application, the thinners were increased slightly and the fan width narrowed from wide open. The gun was held at an angle of about 30 - 35 degrees to the wing surface with the rear fan nearly parallel tracking the spray line and the top side blending the previous pass. resulting in a smooth glossy even finish.

Note: Doing it again I would spray lengthwise on the wing to reduce overspray

This is an entirely different task as the paint required a catalyst and is mixed in a 2:1 ratio and it is potentially dangerous. For all paint 2K operations, the builder wore a full mask with external air supply supplied by a separate compressor, this is only required for the 2K.

At locations, where covers are to be installed are masked before painting to create a clear indicator to anyone that something is missing when final assembly is complete.

Finally, 2k Satin Clear was prepared in the same way and two light coats applied.

Comment
Painting, at last, painting at last.........!! 

The front leading edge of this aircraft was riveted using countersunk pop rivets as discussed with the factory in the early days, since that time the factory has gone all dome for a number of reasons but mainly from the experience gained from multiple airframes. My efforts we a mixed success with the primary issue being dimpling in place with a hand tool, doing this again I would have dome riveted along the rib line and countersunk rivets along the stringers to remove the visual intensity that creates.

The next task will be to have the signwriter to detail the underside of the wing to reinforce that military-style theme of the project along with the roundels and will be covered in a separate blog.