Priming

Page 6-4 Step: States in part: Double check that all parts are properly deburred and prime the parts, if desired, in preparation for riveting.

Used my roller workbench to hold the parts prior to cleaning

It was decided before I even started the build that I was going to prime.  The debate is if you don't prime the plane will last 50 years, if you do prime it will last 150 years... I'm not sure how scientific that is, and I should note that I cruise around in a 40-year-old plane that has no internal priming and I have yet to fall out of the sky. So, needed or not it's something I'm going to do for peace of mind.

That gets to the how to in terms of products and process to use.  Can be as simple as a self-etching rattle can, or some 6-step process which includes numerous caustic chemicals to clean and etch with prior to priming.  I picked something in between that yield good results.  I started out using a Scotch Brite pad and a spray bottle filled with Prekote and following these directions, cleaned and etched up each part.   Using a hose, I rinsed off piece thoroughly to make sure all the sudsy Prekote was off and then set the pieces on my paint station rack to dry.  Skin being to large I just set it up right to dry.

Post paint

The primer I decided to use was a 2-part Epoxy primer called AKZO. People seem to have solid results with this so that was the deciding factor.  Now I haven't used a pneumatic spray gun since 9th grade so before spraying I watched a few videos, practiced with water and tried to hedge the chances of fouling something up.  My first mix I went with a 1:1 ratio of the AKZO base and curing catalyst.  Per recommendation let that sit in a cup for about 30 mins stirring every 10 or so.  I loaded the spray gun up and got to painting.  It was surprisingly a lot easier than anticipated.  Since I did a small batch of mix I got one side of the parts painted before running out.  It looked to be a bit 'thick' which was either technique or product... blaming the product I decided my next batch was going to be equal parts base, curing and some TR-19 thinner.  The next round of spraying seemed to look about the same color wise, maybe dried faster... not sure but since I have a gallon of it, will be using the TR-19 thinner moving forward.

After things dried a bit I gave each piece a quality assurance run through.  Having so many parts on the rack I missed several of the flange pieces and didn't coat as well as I would have liked.  Put blue tape on any parts I wanted to go back over and made a small 6-ounce batch of primer and went over all the areas.  Going to give a good 24 hours of curing time before I start putting the parts back together....  Okay I lied, I'm antsy and wanted to rivet something so while that second back of primer was resting, potting or whatever it's called I decided to rivet the rudder stops to one of the hinges.

Riveting that piece took all of 5 minutes using the pneumatic squeezer.  Using the rivet gauge I QA'd my work and everything was great. All in all, it was a lot less painless than I thought it would be, the hardest part being the cleanup.  The good news is I used an inexpensive HVLP Gun from Harbor Freight.  So even if the gun gets gunked up after 4-5 times of use then I can just get another.