alodine and epoxy primer

[Mike Davis]

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This is a repeat of the same question I have asked on RAH.

There is a great deal of written opinion that alodining the exterior of a
6061T6
aluminum airframe before applying the epoxy primer is the best way to go. I
would prefer not to use the alodine simply to avoid the environmental
impact,
but don't want to repaint for a looong time. (We drink well water and
spreading
chromate laden rinse water around doesn't seem like a good idea.)

Randolph for instance does not suggest alodining. They do suggest their
metal
cleaning product but the fine print says it is intended primarily to roughen
alclad and my 6061 is not alclad.

Has anyone had good results with just detergent cleaning and scuffing with
scotch brite pads?

thanks
Ken

[Mike Davis]

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From: "Tim Carter" <tlcarter@email.msn.com>
To: "'Murphy Rebel'" <murphy-rebel@dcsol.com>
Subject: RE: alodine and epoxy primer
Date: Tue, 18 Aug 1998 18:29:05 -0700
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Yes. I have had good results up to this point not using any alodine. I have
chosen not to alodine for the same reasons you mention.

I do, however, use a Scotchbrite pad (maroon color) as a rule, and in some
cases on the smaller stuff, phosphoric acid to help with the cleaning
process.

I have over the life of my project used three different primers:

1) System 3
2) PPG DP40
3) and now, because I live in the welfare state of California, PPG DP40LF
(lead free)

I quit using System 3 because of all things, I found out quite by accident
that it was not waterproof. That is the most tenacious stuff when it cures,
very durable, and not even a soak in acetone will get rid of it. But water
will. Soak it in water for a week, you can peel it off. When I called the
System 3 guys with this news, they didn't flinch. Their solution was to
topcoat the primer with their clearcoat, which is waterproof. Is that silly
or what?

Anyway, after that I moved on to PPG DP40 on the advice of an RV builder.
Good stuff, but not as abrasion resilient as the System 3 (except for it
appears to be more water resistant). And then I moved to the DP40LF, which
is not as good as the DP40 to spray thin, and it costs more. I am thinking
very seriously about going back to PolyFiber Epoxy Chromate for the
remainder of the build.

Anyway, the net net of this ramble is this:

I use Scotchbrite alone to rough the surfaces, and then I clean with PPG
acrylic cleaner (DX 330 is the formula number I think), and then I prime
with DP40LF. No problems. I have some pieces over three years old with
primed surfaces, and no chips, no fades, no paint coming off problems.

Some tell me I am doing the wrong thing, and just as many say my method is
OK. It will continue this way and then we will fly it.

Hope that helps.

Tim
#438R
-----Original Message-----
From: klehman@albedo.net [mailto:klehman@albedo.net]
Sent: Tuesday, August 18, 1998 11:59 AM
To: Murphy Rebel
Subject: alodine and epoxy primer


This is a repeat of the same question I have asked on RAH.

There is a great deal of written opinion that alodining the exterior of a
6061T6
aluminum airframe before applying the epoxy primer is the best way to go. I
would prefer not to use the alodine simply to avoid the environmental
impact,
but don't want to repaint for a looong time. (We drink well water and
spreading
chromate laden rinse water around doesn't seem like a good idea.)

Randolph for instance does not suggest alodining. They do suggest their
metal
cleaning product but the fine print says it is intended primarily to roughen
alclad and my 6061 is not alclad.

Has anyone had good results with just detergent cleaning and scuffing with
scotch brite pads?

thanks
Ken

[Mike Davis]

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To: <murphy-rebel@dcsol.com> (Murphy Rebel)
From: Bob Patterson <bob.patterson@canrem.com>
Subject: Re: alodine and epoxy primer
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Date: Tue, 18 Aug 1998 22:45:37 -0400


Alodine is not necessary for a good bond - it is just a surface
cover to prevent oxidation. You can get a good bond with the primer by
using a Scotchbrite pad & Alumiprep (a mild etch available from Leavens,
etc)
The Alumiprep is mildly caustic, and must be rinsed off thoroughly, but it
would not be violently toxic like the Alodine.

The secret is to get the primer on ASAP after etching, as the
aluminum is bare, and will oxidize rapidly, AND the airframe attracts oils
from handprints, dust, etc. Getting the primer on fast prevents many
problems.

The Polyfibre epoxy zinc chromate primer supplied with the kits
has been proven to be the best corrosion protection available. It 'may'
not be compatible with some newer paints, which are sold as "systems", but
I haven't heard of any problems with RM or PPG paints.

....bobp

----------------------------orig.---------------------------------
At 02:59 PM 8/18/98 -0400, you wrote:

This is a repeat of the same question I have asked on RAH.

There is a great deal of written opinion that alodining the exterior of a

6061T6

aluminum airframe before applying the epoxy primer is the best way to go.

I

would prefer not to use the alodine simply to avoid the environmental

impact,

but don't want to repaint for a looong time. (We drink well water and

spreading

chromate laden rinse water around doesn't seem like a good idea.)

Randolph for instance does not suggest alodining. They do suggest their

metal

cleaning product but the fine print says it is intended primarily to

roughen

alclad and my 6061 is not alclad.

Has anyone had good results with just detergent cleaning and scuffing with
scotch brite pads?

thanks
Ken

[Mike Davis]

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From: NMFN98A@prodigy.com (MR PATRICK S DALY)
Date: Wed, 19 Aug 1998 13:49:05, -0500
To: murphy-rebel@dcsol.com
Subject: alodine and epoxy primer

Ken There is a product that is called ACL 50 or something like
that might be what you are looking for. I have used it on some
acft. with good results. It is easy to use by a spray device but
would be
on the tempory side because the manf. recommends every five years.

Don