Priming cabin area parts - 7 hours

 Big day of priming today. The parts are big and a bit of work to scuff all of them and prep them for painting. I managed to do the best I could and get it really clean and acid etched. The side steps being steel got a slightly different treatment. The entire assembly was buffed clean with a non-ferrous wheel and then 220 grit sandpaper. Wiped down with MEK and sprayed.

All these parts are hard wearing parts and thus got the epoxy primer treatment. I only have one or two more priming sessions with epoxy primer.... and good riddance. This is a painful part of the build because the epoxy primer is so labour intensive, messy and ridiculous over-spray.

Later in the evening, I decided to install the pieces and nutplates on the flap channel and the baggage side covers.

 

Big priming day - 7 hours

I needed to get some parts primed in order to keep making progress on the build. There is a considerable amount of parts that need to be primed (baggage floors, seat floors, flap parts, etc etc). I've been holding off for some warm weather so that I can prime outside but it looks like its not going to come for some time. So I just have to bite the bullet and do a priming session in the garage.

I set up the all of the buckets, tarps, etc so that I can do a priming run.

Its a lot of work to prime. Wash, scrub, acid etch, rinse, MEK, prime.  I did as much as I could, but at the end of the session, I didn't have to drive to keep priming. I still have all the big panels to complete (Baggage bulkhead, baggage floors and panels, forward seat floors) I wait for a warmer day to do those. I don't need them done just yet.

More Priming - 10 hours

 Another big day of priming. I touched up some of the pieces I didn't get good enough yesterday and then I primed the floor skin and the side skins. I am absolutely chemical-ed out!

 

Started priming - 10 hours

 Ready to start priming and it was a huge day. For the cockpit I had decided to change things up and go with a 2-part epoxy primer. No doubt the cockpit is going to take a lot of abuse so why not toughen things up. The prep was extremely long. Wash, scrub, acid etch, so on

Countersinking Wing Platenut Attachpoints & Priming - 3.5 hours

I completed countersinking the #40 holes for the platenut attach points. It was a slow process as I took my time to ensure the countersink cage is nice and flat on the piece. I would check, check and re-check as I went. Marking pieces OK when I was happy with the countersink depth.
I've began keeping the laptop nearby. Its quick reference to Vans Airforce / Buildlogs, and of course...Netflix!

I then took an hour to start priming platenuts. This is an idea that I had picked up from wirejock. I reason that it's an extra couple of steps to clean and prime them. But it seems worth it to me, as they are steel and priming will help mitigate rust.

deburred and primed VS#2 - 3 hours

I deburred all the holes for the VS parts and primed them. 

This time I choose to modify my priming methods considerably. On the last empennage I primed everything with 2-part epoxy and it ended up noticeably heavier which did not sit well with me. Not to mention, I have learned lots about priming over the last year and felt this was a much better option for many reasons.

I've decided to use duplicolor self-etching primer. It's easier and cheaper to purchase. It also allows me easily touch-up any areas that I am working on. Much better than the two part stuff.

The 2-part epoxy covers the garage in an incredible amount of dust.

I live in a fairly dry area and intend the plane to be hanger'd, so the need for corrosion protection is considerably less than if I live near the coast or choose to keep it outside.

Did I mention weight? I have decided to only prime mating parts. The skins will be left nearly unprimed except where ribs and stiffeners meet. The result should be pretty light

Priming - Round 2 - 6 hours

I really hate priming. I've tried to avoid it as best I could but I needed to get a bunch of parts primed today. It was the worst weather for it -32deg C. I heated up the garage and set up. Started in on washing, scrubbing, rinsing, cleaning, priming. It is a very nasty process as the pro-Form Degreaser and the MEK are pungent. The 2-part epoxy primer is downright nasty stuff.  It burns your eyes and even with the respirator on, it burns the lungs a bit. It has a tenancy to seep into the house as well. I can't wait till summer when I can do this outside.

I finished priming the HS parts and the rudder parts. I have most of the elevator stiffeners primed too  

Priming the Vertical Stabilizer and Rudder - 4 hours

I started priming the Vertical Stabilizer and Rudder today. After a bunch of reading on the forums, my priming tests and a quick discussion at the recent EAA meeting I had decided on a non alodine treatment. I figured just a straight 2 part epoxy primer would suffice. I do not live in a maritime environment so I figure that the maximum protection alodine would provide would be overkill for my needs. I settled on a good surface prep and then a 2 part epoxy primer. This morning I decided that I wanted to get a bunch of priming done on my parts before I go away next week. I picked up two big 50 gal containers from Lowes. I would use these to wash my parts.

Here is the priming process;

1. Parts are deburred and checked. Parts are gone through with a light scrubbing with scotchbrite red.

From this point on, all parts are handled with gloves on.

2. Just a few parts are washed thoroughly with water and Dawn detergent.

3. Those few parts are rinsed and scuffed with red scotchbrite in the water (gray scotchbrite for skins)

4. Parts are then dried with air and a clean microfibre cloth.

5. Everything is wiped down with Pro-Form wax and degreaser.

6. Everything is then wiped down with MEK.

7. Parts are primed with spray cans of Spray Max 2K primer

8. Repeat step 2 thru 7 for the next few parts.

I chose this process as it allowed the parts to be thoroughly cleaned and minimized the exposure of the newly scuffed layer of aluminum to oxygen before the primer is applied. It is fairly tedious, however with some good music playing time flys by and I can take comfort that I am at least getting the best surface prep that I think I am capable of.

The ugly side of the priming is that I do notice the increased weight of the 2K primer (Darn!!). I am giving the skins a light coat with the emphasis being applied to areas of mating surfaces so hopefully I mitigate weight as much as I can with the primer. The benefit of the 2K primer is that it is extremely tough so it will offer a level of protection when I get into riveting.

At the end of the day, I know I will be penalized for weight on the priming....however I intend to shave some weight in other areas (i.e. VFR Glass EFIS instrumentation, LED lighting, Beringer brakes and wheels, Fixed pitch propeller, etc) so hopefully things will balance out in the end.

As a side note....Its taken just over 2 full cans of primer to do the Rudder skins and the VS assembly. There's not much in a can. Ouch...that's an expensive method of priming. I estimate that it will take another 3 or 4 cans to complete the empennage. Also....it oversprays like crazy. Gets cloudy quickly in the garage when I spray!

More tools and primer investigation

I submitted a questions to the Vans AirForce Forum on a back rivet plate. I asked about cold steel vs stainless steel. I also asked how to keep the cold steel from rusting. Everyone came back with a recommendation for cold steel, and most said a light coating of WD-40 prevents rust.  So I ordered 3/8" x 6" x 24" cold rolled steel bar from Metal Supermarkets and picked it up on my way home from work. Had an interesting phone conversation with the owner of Anderson Anodizing in St. Albert. I called him looking to see what the charges might be to have the aluminum alodined for me (I have serious concerns of my abilities to alodine the parts at home....both during the winter time, and in safe handling/disposal of the Alodine) His recommendations to me was that he did not feel that the alodine was necessary. His concerns were more for the proper cleaning of the aluminum so as to allow good adhesion of the primer. He agreed that the 2 part epoxy was a great choice and that it would help prevent corrosion.  After reading Vans recommendations on priming  coupled with my recent conversations. I have decided that MY best option for priming the interior is a very careful prep and clean of aluminum parts followed by two thin coats of epoxy primer (the overall weight of 2 part epoxy being a concern too). I'm glad that I have finally come to a consensus on the primer....It has been haunting me for the last week!            

Test Priming Day 3

Woke up this morning and checked the 2K epoxy primed pieces. No question that this primer is tough! Resists scratches. When I got home from work...tough as nails (after 23hr dry time). The only concerns that I have had all day was with respect to metal prep. I phoned a friend who owns a local autobody shop. He confirmed to me that the two part epoxy primer was his recommendation for the job, however he indicated that he saw no need to apply alumiprep, but was fairly certain that Alodine was a good idea. He said that is the process used in aviation that he was used to seeing. He indicated that the process helps open up the aluminum to accept the primer. I am convinced that it is superior, however I have serious concerns with applying this method at home. Alodine is extremely nasty stuff, and the application process requires Alodine to be washed with clean water. How do I do that in winter? Do I want to Alodine in the house???

I've been looking at Endura Paints under aviation primers and they have two recommended methods for preping thin aluminum. The Alodine method, or a Biodegradable method using a cleaner and a Metalink product. According to the data sheet the metalink is waterborne "Endura MetaLink is an environmentally friendly, chromate free, pre-bond adhesion promoter for bonding metal alloys such as: Aluminum (#2024, #5052, #6061, #7071 and #7075)". The only concern I have is a lot of parts are alclad....not alloy....So how will this work? Hmm. Geezze my head hurts.

Update - 10:00pm Epoxy test pieces are great. Can't scratch a thing on them. I have tried to wipe them with MEK and virtually nothing comes off! 

Test Priming Day 2

Just after midnight  (about 7 hrs after spray) I checked the primer, scratch test has improved greatly but I was able to scratch it although considerable pressure was required (See bottom left corner). I work up this morning and checked the sample primer pieces. The primer has hardened to a point where it is really difficult to scrap with a finger nail (See bottom right corner). Almost no primer was scraped off the aluminum despite great effort.  When I got home from work (23hrs after spray) the test piece was not able to be scratched with a fingernail (see right side). Only when a screwdriver was used could the primer be scraped. (see center)

After 28 hours, I tried to remove the primer with a moistened towel. MEK and Acetone took the primer of the Aluminum very easily. The degreaser took a bit of rubbing in order for the primer to be removed. Gasoline had no effect on the primer. using a light colored cloth there was no transfer of dark primer onto the cloth...Didn't expect that. I prepped four new pieces of aluminum with Acetone, MEK, Degreaser and one just plain scuffed and wiped dry. Acetone seemed to evaporate almost immediately, more so than the MEK. I let the pieces dry outside for a while.  Then I sprayed two coats of Spray Max 2K epoxy primer. The primer application was really smooth and covered well. It occurred to me that in comparison, the Dupli-color required 2 heavy coats to cover, while the 2-part epoxy covered a bit better with only one pass. I waited 30min for the second coat. I noticed that the pieces took time to be dry to touch, after 30min the pieces where still a bit tacky.  (Note: The placement and timing of the scratches is the same as the sequence above.)  After 1 hour, the primer was able to be scratched with a fingernail. It seemed more like I was removing the top layer of the coat as I could not scrape down to aluminum. After  4 hours, the scratch test is similar to the Dupli-color after 24hrs. You have to press extremely hard to scratch with a fingernail, even then you only seem to be distressing the top layer....not quite breaking through the top layer.