Corrosion Proofing

DuPont makes Variprime 615S/625S Self-Etching Primer. It has been
recommended to me by a retired FAA engineer.
I saw an Ercoupe and some Cessna wings being rebuilt at Wesport Airport
(Dead Cow) in Wichita. Both were primed with Variprime.
I am considering using Variprime to corrosion proof my Skylark.
Several years ago I painted a C-205. The process used was Alumi-Prep
33, Alodine, Dexter 10P-2/EC 139 Epoxy Primer and AlumiGrip paint(US
Paint).
I also have some Dexter 10P-2 Epoxy Primer, MIL-P-23377. The Dexter
product worked very nicely on the C-205. It too is being considered for
corrosion proofing.
I look forward to hear about everyones experineces and recommendations.

DuPont makes Variprime 615S/625S Self-Etching Primer. It has been
recommended to me by a retired FAA engineer.

As far as I know, this self etching primer needs to be coated with a sealer,
such as urethane paint. O It is porous, and therefore is not a moisture
barrier.

I use Akzo Nobel 2 part epoxy primer (the ugly lime green stuff). You need
to do the alodine thing (pain in the butt), however the surface now is
scratch proof and moisture resistant. It meets Boeing spec. BMS 10-11 for
fuel resistance etc. Very good stuff, and about the same cost as Variprime
if you include the Alodine. Labor cost is the only variant. You can get
other brands that meet BMS 10-11 as well.

You can also get some self etching spray bombs, such as Marhyde, however
they scratch very easily.

Variprime works just fine... It contains zinc and is a corrosion
inhibiter... It is hard once cured... While it may not be as
impermeable to moisture as some topcoats, unless you are immersing the
plane in the ocean, it is good enough...

Now if you are doing the interior of an assembled aircraft where the
fayed joint surfaces cannot be coated, why not skip the work and cost
of a primer and just fog the metal with ACF50 every other year?

denny

"Denny" wrote:
just fog the metal with ACF50 every other year?

Do you use that stuff? What do you think of it?

I've been using CorrosionX for years with good results, but I've heard
ACF50 is better and doesn't weep out of the airplane as much.
--
Dan
C172RG at BFM

They are both good prducts and work as advertised... ACF50 seems to
make less mess... If you are happy with X, I wouldn't change... I was
just making the point that the exposed metal surfaces in an assembled
airplane are not the major site of corrosion, it is the fayed joints,
and coating them on the outside with paint will not protect them... I
spoze one could spray Variprime and also use ACF50, seems redundant
though...

denny

On interior surfaces large aircraft use a product called Dinitrol. It
gets sprayed on at manufacture and is there for the life of the
aircraft. It keeps moisture from getting between the joints.

On 21 Apr 2005 03:34:21 -0700, "Denny" wrote:

They are both good prducts and work as advertised... ACF50 seems to
make less mess... If you are happy with X, I wouldn't change... I was
just making the point that the exposed metal surfaces in an assembled
airplane are not the major site of corrosion, it is the fayed joints,
and coating them on the outside with paint will not protect them... I
spoze one could spray Variprime and also use ACF50, seems redundant
though...

denny


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On interior surfaces large aircraft use a product called Dinitrol. It
gets sprayed on at manufacture and is there for the life of the
aircraft. It keeps moisture from getting between the joints.

That's the stuff my A&P had me paint all over the spar (and adjoining
structure) when we performed the dreaded Service Bulletin 1006 on my
Cherokee 235, a few years back.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On 21 Apr 2005 03:34:21 -0700, "Denny" wrote:

They are both good prducts and work as advertised... ACF50 seems to
make less mess... If you are happy with X, I wouldn't change... I was
just making the point that the exposed metal surfaces in an assembled
airplane are not the major site of corrosion, it is the fayed joints,
and coating them on the outside with paint will not protect them... I
spoze one could spray Variprime and also use ACF50, seems redundant
though...


They tell me that good old LPS-2 works quite well.
You can tell if they did a good job if you take the plane out and let
it set in the sun. It'll drip for about two weeks.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
denny