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Anyone regret not priming?

Roy25101

Active Member
I figure these aircraft have been in existence long enough that perhaps someone might have some regret not priming while building. I've been through the linty of information on why or why not but do not recall anyone specifically having any issues with the "not". Perhaps I missed it.

In advance, thank y'all for the information.

P.S. For the parts that are not Al-clad and require priming these 2k two part epoxy primers in a rattle can are fantastic. Take care.
 
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P.S. For the parts that are not Al-clad and require priming these 2k two part epoxy primers in a rattle can are fantastic. Take care.
please tell me more about this product? Sounds really cool...
 
I figure these aircraft have been in existence long enough that perhaps someone might have some regret not priming while building. I've been through the linty of information on why or why not but do not recall anyone specifically having any issues with the "not". Perhaps I missed it.
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Hard to prove a negative. I suggest you go to any FBO and ask how often they do CorrosionX treatments.

The guy I sold my RV-10 to is a long time spam can pilot. One of the first questions he asked me was "when was the last time you applied CorrosionX?". I explained to him that one applies CorrosionX on airplanes not properly protected from corrosion during construction.

Prime - you and the people that fly your plane after you will be happier.

Carl
 
I've used a few of the 2K epoxy primer cans. They go on quite nicely, but you only have about 2 days to use the can once activated.
 
Risk decision

My 1969 C172 had the CorrosionX treatment a couple of years ago due to very light corrosion from wing root insulation that got wet during a storm at Oshkosh. If it had not gotten wet I'm convinced it STILL would be corrosion free. In the build of my RV7, I'm not priming the Alclad. I'm 68 years old. If I finish my RV in a couple of years, I figure I should be about 116 years old before I start worrying about corrosion. :eek:
 
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My 62 year old certified airplane isn't primed. It's lived most of its life in the dry states like Colorado. The only corrosion it's ever picked up was due to six months tied down outside of Philadelphia. The thee years it was in a hangar on the west coast, three miles from the beach, did nothing.

That said, I'm priming my RV-3B -- for ease of selling it eventually. But that's the only reason.

Dave
RV-3B now on the fuselage
 
Old and Tried

My 62 year old certified airplane isn't primed. It's lived most of its life in the dry states like Colorado. The only corrosion it's ever picked up was due to six months tied down outside of Philadelphia. The thee years it was in a hangar on the west coast, three miles from the beach, did nothing.

I agree with this. My '61 Debonair had no primer inside and no corrosion up until 2012 when we parted ways. An argument could be made that Beechcraft started using primer on the interiors of it's aircraft in the late 60's, and therefore, if it was the right thing for Beech, it should be right for me.:rolleyes:

I imagine the primer debate will continue in perpetuity and I simply have my opinion, which is that for the internal structures, I don't use primer and instead use a product like Corrosion X after the build, and then re-spray every one to three years (depending on your climate), which will provide active corrosion protection rather than relying on the passivation that primer by itself brings.

The big advantage of an anti-corrosion spray is that if you did NOT prime the interior of the airplane, or you bought an airplane without primer, you can still provide corrosion protection after the build.

Here's the thing, even though my certified airplane was primed, I still spray it internally every two years. It takes me 1-2 hours to do and uses a little over a quart of the stuff to do the whole airplane, and the stuff gets into everywhere. If you have corrosion or a loose rivet, you will soon know where it is, as the CorrosionX will provide a dirty streak out of wherever the corrosion was. The full benefits and description are available on their website, but I will add that it does a great job of keeping the interior parts shiny, stops corrosion in progress and presents further corrosion - it's main purpose. If weight is an issue, this is a lot lighter than primer (an RV-12 only needs about a pint of this stuff).

It does have it's minor drawbacks, which are - if you spray everything down FWF with the cowling off, better have a pan under the airplane as all gook and corrosion will come off and drip to the floor. And you shouldn't use it within six months of painting, as paint will not adhere to it and it will penetrate and then come out of every imaginable spot and it works through rivets and bolts. As an aside, it's really good at making the engine bright and shiny and is recommended for electrical components as well.

In direct response to OP question, I do not regret not priming the interior of my airframe. I did not prime the wings, control surfaces or fuselage of my aircraft, except where it was called for in the directions - generally only where non-alclad parts were joined, and certainly all ferrous parts.
 
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I was intrigued to until I saw the price and the fact that the pot life is only 48 hours once you "activate" the spray. :eek:

If you want a primer that will prevent corrosion, there are zinc chromate spray cans in lots of colors. https://www.google.com/#q=skygeek+zinc+chromate+spray

There are several reasons for primers, adhesion promoter, base coat compatible with top coats, and corrosion protection (zinc or strontium chromate)

Many fill the first 2, some the third and a few all three. Azko has more paints than ford makes cars, but the popular version noted frequently here fills all three.

So, the rattle cans above are good for small parts that will not get a top coat and don't need to look pretty, or resist acetone after dry. Like contact surfaces inside the HS.
 
I'm a fairly young guy, building an RV-10, and I decided to only prime the parts Vans tells you to in the instructions. Basically, if it was AlClad protected from the factory, I didn't prime it. I've heard too many stories about GA aircraft that looked shiny and new inside after decades of use. I have no regrets, but I'm not flying yet either.. Worst case, I'll treat it later with Corrosion X.
 
On this second plane I'm building, I'm not in the prime/no-prime camp.

Some parts I will. Some parts I won't.

I didn't prime, for example, the trim pieces on the RV-12 nor the Vertical stab.

Why?

I'm so impressed with how Van's engineers have eliminated weight on this kit that I think it's counterproductive to add it back, no matter how small.

And those particular parts can be rebuilt in an afternoon for a few bucks if it came to corrosion, which it probably won't.

And any part that actually is directly exposed to the elements is primed.

Rattle cans for me.
 
I'm in Mike Rettig's camp. Shiny aluminum except in a few places. The painter did prime prior to painting the outside, but that's his business.

John
 
There is no coating, treatment, or process that will prevent corrosion. There are different levels of protection, but nothing makes 2024 corrosion proof.

Alclad is a conversion process which changes the alloy surface to a more pure state which is a lot more corrosion resistant than the base alloy.
Zinc Chromate is a sacrificial coating and toxic deterrent to organic growth. The coating will corrode once the top coat has been compromised and as long as there is still chromate that is unspent, it will protect the base material. However, once the chromate is depleted, corrosion will take its next victim.
Two part epoxies encapsulate the base metal so moisture can not penetrate and set up the necessary electrolysis for corrosion to start.
Corrosion X is a soup of compounds that deposit as a thin film of protection and requires retreatment in many environments.

The level of protection needed to keep corrosion at bay has everything to do with the environment and exposure to water, salt, and other corrosion accelerators. Choose the level of protection that you feel will meet your needs or as some have done, for resell.

I know this didn't answer the question, but there isn't one easy answer, or a silver bullet that can completely eliminate the possibility of corrosion. My current projects skins where anodized, then zinc chronate primed, then top coated. They still corroded due to time, environment, and neglect.

If anybody has regrets about not priming, it would be someone who's airplane was in an environment that had the potential to promote corrosion. Kind of stating the obvious. Someone without regret hasn't been in that same environment.
 
Yeah, it depends.

My project came to me in the canoe/almost-a-quick-build stage, and had been extensively interior-primed with AKZO. It's destined to make a lot of trips to the Carolina coast where it will sit unhangared for days at a time within earshot of the surf. So as I moved forward, I primed the remaining pieces with self-etching single part rattle can primer, mostly on the fay and inaccessible underside surfaces. Anything completely removable and interior, such as seat backs, was left natural on all sides, except the fay surfaces between components. Just too easy to remove and replace if ever needed, and not a structural issue even if corrosion were to start there, as an example.

No point adding totally unnecessary weight; it does add up. As does cost.
 
There is no coating, treatment, or process that will prevent corrosion. There are different levels of protection, but nothing makes 2024 corrosion proof.

Ok, so I agree with your sentiment, but I disagree that corrosion can't be prevented. It can, it's just a matter of how serious you want to get about it and the money you want to spend.

Corrosion is simply an electrical process of oxygen reduction. If you inhibit the voltage potential or create a barrier for oxygen access, you will stop corrosion. And there are ways to prevent corrosion. One is to create a permanent barrier; such as marine coatings used by the Navy such as a DEVRAN 200 series coating, which adheres in ways that defy logic and is impervious to any oxygen penetration, however even it starts to break down above 230ºF. Of course, you need a governmental budget to afford it.

The other way is to provide cathodic protection, which in the case of CorrosionX, is the provision of a "sacrificial anode" chemical, which more readily gives up electrons to the reduction process than the material being protected; in this case, aluminum.

If you're really serious about it (such as if you keep your airplane next to a beach in Florida), you can go with the "belt and suspenders" approach of priming with a sacrificial anode type primer (zinc chromate is one) and then spray with a corrosion inhibitor on biannual basis, such as Corrosion X. Or you can just say "screw it, it'll be good for the rest of my flying career" and forget about any protection knowing the plane will need either a lot of help or the scrap yard many years later.
 
Maybe I have OCD Syndrome...

Reading through the various post on this thread makes me feel like maybe amongst the common RV builders, I could be a wacko, a over the top perfectionist or worst I have incurable major OCD syndrome :rolleyes: ....

In the ever lasting debate about to be a primer or not to be a primer, I chose to be a primer, with no exception to the rule.... Why? Because

1) I make no compromise on the quality of my build, despite the sometime higher cost and slightly increase weight.
2) This is what I have been taught to do in Aircraft Manufacturing School, and subsequently working on the Aircraft Manufacturing Industry.
3) I will fly and operate my RV in an environment where you just look at some thing, and it corrodes, especially in our cold & humid snowy Eastern Canada Winter.
4) I want my aircraft to last and outlast me
5) If I ever sell my aircraft, I want the future owner to have full confidence on the quality of my build.

That all said, picture below is yesterday evening and today all day production....RV parts that have been scuffed, then subsequently dipped in Alumprep 33 and Alodine 1201 baths. These parts will be primed with Sherwin William Green Zinc Chromate epoxy primer at a local bodyshop on Monday morning

DSCN3013_zpsumlwo2bl.jpg


RV Experts will recognize RV-8 fuselage parts :) I just love to turn aluminum RV parts into gold ;)

Do I regret priming my RV-8 ? Obviously not ! What I regret though is that it takes me an awful lot of time to do it. For the next RV someday, for sure I will work on a "lean manufacturing process" to make this faster....
 
I'm in the "keep it simple" camp and only prime parts exposed or what Van's indicates in the instructions .. however .. I have a question that came up last night during my build:

If Alclad is a surface process, and a lot of the parts from vans require trimming and cutting, aren't those areas that are trimmed and cut (or accidentally scuffed) no longer Alclad? Does anyone that has not primed see corrosion on the edge of ribs, etc, over time?
 
I'm in the "keep it simple" camp and only prime parts exposed or what Van's indicates in the instructions .. however .. I have a question that came up last night during my build:

If Alclad is a surface process, and a lot of the parts from vans require trimming and cutting, aren't those areas that are trimmed and cut (or accidentally scuffed) no longer Alclad? Does anyone that has not primed see corrosion on the edge of ribs, etc, over time?

Haven't seen any evidence of edge corrosion on unprimed Alclad in my hangared 1999 RV-6. However, those components are located in the interior of the plane and protected from outside exposure.
 
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My 1969 C172 had the CorrosionX treatment a couple of years ago due to very light corrosion from wing root insulation that got wet during a storm at Oshkosh. If it had not gotten wet I'm convinced it STILL would be corrosion free. In the build of my RV7, I'm not priming the Alclad. I'm 68 years old. If I finish my RV in a couple of years, I figure I should be about 116 years old before I start worrying about corrosion. :eek:

My thoughts exactly! :)
 
Priming

On my slow-build RV-7 project, finished in 2009, I used self-etching rattle can primer on the non-alcad parts. I scuffed up the parts with scotch-brite, then cleaned them well before spraying. It's hard to believe, but I've been happily flying my 7 for eight years now, and have over 1,000 hours on it. It's always been hangared; the airport is just off the Chesapeake Bay. I have yet to see evidence of any corrosion on the airplane. I can tell you the airplane is going to last a lot longer than I am!
 
I own a -4 that was built in '91. Spent its 1st 20 years in Arizona; rest of the time in Mississippi. Only light discoloration on the inside of the wing bottom skins. (And some light corrosion around chipped paint on the outside...)

This thread is the 1st time I've heard of alclad being called a 'conversion coating'. Supporting docs? I've always been told that it's just a super thin layer of pure aluminum applied to the 2024 alloy.

Charlie
 
I had my tail cone in a basement for just under a year. Despite having dehumidifiers down there, moisture found a way around the bottom skin and battery mount ribs and cause a lot of corrosion. I had hastily sprayed the Duplicolor self etching primer (not applied well, my fault) and it corroded underneath the primer.

I regret not priming!!

I started using SEM out of a spray can for ease of use on the wings and fuselage. Great product, tough as nails, easily applied.
 
Tim - I've seen your blog pictures and it was heart wrenching to me.

Can you elaborate on what you think went wrong? Why that one area?
 
First it was storing it in the basement. However, I will say that the basement was still a much more controlled envrionment than what an airplane will see in it's normal life (outside, rain, hot humid hangar, etc). I had it sitting on the ground with just a scrap of carpet underneath. I believe the metal acted as an attractive surface for moisture to collect and that happened to be the lowest spot.

Second, it was the condition of that piece. The tail kit is old (originally purchased in 2004) and there were more than a few scuffs and scrapes to that area. Any damage to the pristine surface of the Al from Van's can invite corrosion if not properly treated.

Third, was the crappy application of primer. The original builder did not prime for several reasons of his choosing. I went back and forth and decided against it initially. However, after seeing more and more light filiform on pieces, I changed my mind and primed. Initially I used the Duplicolor self etching primer and it's not a quality product in my opinion. I also did NO prepping to the tail cone before I shot it. It was a last minute decision before storing it at the time that "hey, some primer is better than nothing at all" thought. I simply spray painted over a completed assembly, so no real protection from it.

My advice is find a method and product that works for you and do it. It can be done simply, quickly, easily, and cheaply. No point in worrying any more than you need to about the condition of areas invisible once it's built.

Primer isn't a guarantee of no corrosion, it's just a form of insurance that I will not build without!
 
I had it sitting on the ground with just a scrap of carpet underneath.

My guess is the carpet did you in, wicking up the moisture in vapor from the concrete.
It is just a guess and not meaning to hinder your other points.

Do not store parts in contact with anything that can absorb or retain moisture.
 
My guess is the carpet did you in, wicking up the moisture in vapor from the concrete.
It is just a guess and not meaning to hinder your other points.

Do not store parts in contact with anything that can absorb or retain moisture.

To add to that, Concrete has lime in it. It's very possible that the situation was compounded by the carpet and concrete.

~Marc
 
I use 2k chromate epoxy primer that airbus uses on the whole inside.

I have been working on the empenage for a few months. I already have filiform corrosion around rivets on my finished parts on the outside! So I regret not priming the outside as well. I have no way of telling if corrosion is right under the rivets and doing its thing there.
 
I've also been actively searching for someone who really wishes they had taken the time to prime the inside surfaces. Haven't found a single such story though.

I'm in the 'priming everything, but not sure why' group. It sure adds a pile of work, so far that's all I can see. Hopefully one day I'll find myself incredibly glad I did, although that might be as unlikely as finding someone that is terribly regretful for not priming!
 
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