[rebel-builders] Pro-Seal, Primer, or Chromate

[Ted Waltman]

Jerry,

I chromate all mating surfaces for sure. Generally, though I know it adds
(some?) weight, I fully chromate all aluminum. For a time, I also had
dipped each rivet tail in Stits EP-420/EP-430 primer before pulling the
rivet (I know several builders who have done this). While this last "dip"
step sure makes for a much better/stronger rivet, it also makes it darn near
impossible to later drill out any of those rivets in a clean manner without
enlarging the diameter of the original hole--so I do no longer recommend
this "dipping" step.

To make your work easier, I started to debur and prime all parts before
assembling a structure. In other words, if I were doing the rudder, for
instance, I'd lay out all the rudder parts, including the skin, and
debur/prime everything. That way I had a mini-inventory at hand, didn't
have to go searching for this or that in the midst of construction, and had
everything ready to go together without waiting for a part to dry.

Ted

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Jerald
Folkerts
Sent: Thursday, December 30, 2010 7:11 AM
To: rebel-builders@dcsol.com
Subject: [rebel-builders] Pro-Seal, Primer, or Chromate

Gentlemen,

I'm getting ready to pull the first rivets within the next
couple of weeks. I've been reading the Vans Air Force Forum lists on
pro-seal, automotive primers, or chromates and have found a variety of
opinions. It's not my intent to start a controversial discussion, but would
like to hear your opinions as to the best quality (something that will hold
up over time) and efficient method of sealing seams/rivets. In addition,
are there any techniques for your preferred method that would make my work
easier?



Happy New Year

Jerry Folkerts

SR2500 #093









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[Jason Beall]

Having just had to drill out a bunch of rivets on my lower tail wrap, I highly suggest you don't dip your rivets in anything that will 'glue' them in!

Man, drilling the AVEX rivets out is a b@&ch! FWIW, I found it easier and cleaner to drill the rivet all the way through with a 1/8 inch drill (not #30) than to only drill the head and snap the head off. I did considerably more damage trying to get the rivet 'tails' off that I did by just drilling the rivet all the way out. Your milage may vary.

-Jason



--- On Thu, 12/30/10, Ted Waltman <ted@vafm.org> wrote:

[quote]From: Ted Waltman <ted@vafm.org>
Subject: RE: [rebel-builders] Pro-Seal, Primer, or Chromate
To: rebel-builders@dcsol.com
Date: Thursday, December 30, 2010, 7:34 AM
Jerry,

I chromate all mating surfaces for sure.

[Bob Palmer]

I used Proform etching primer and I do not recommend it. Properly
applied it weighs more than Zinc Chromate. Once you start with one there
doesn't seem to be a good place to change over. I used Zinc Chromate
before and for our floats I will be dedicating a spray gun for that purpose.

Bob.

On 12/30/2010 6:11 AM, Jerald Folkerts wrote:

Gentlemen,

I'm getting ready to pull the first rivets within the next
couple of weeks. I've been reading the Vans Air Force Forum lists on
pro-seal, automotive primers, or chromates and have found a variety of
opinions. It's not my intent to start a controversial discussion, but would
like to hear your opinions as to the best quality (something that will hold
up over time) and efficient method of sealing seams/rivets. In addition,
are there any techniques for your preferred method that would make my work
easier?



Happy New Year

Jerry Folkerts

SR2500 #093









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[bransom]

Jerry,
Not that I'm eager to do it, but I've found little trouble removing chromated
rivets (EP 430). With a little care to keep the drill bit centered, one can
usually get just a little below where the head comes off. Then use a snap
punch or quick and light hit to punch the remainder through and there is no
dent in material. (Pliers on the back side better, if you can get there.)

So, I've stuck with the MAM recommendation and dipped rivets for the whole
airframe, as well as wetted all facing parts before joining. To chromate rivets,
I grab a bunch, fumble them over to a bouquet and dab them all up with a
brush of EP430, then stuff them in the holes between clecos. Pop that batch
and repeat. 1,000 times ;) The only odd part of this is that some larger
assemblies, the EP430 will partly cure before the pieces are joined.

I'd not use pro-seal for anything that you might want to someday take
apart. On the other hand, I've used it on my ultralight for non sealing
purposes, such as between a couple nearly touching rib braces to assure no
chafing. (It has give/elasticity.)

Happy riveting!
-Ben



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[Drew Dalgleish]

At 08:11 AM 30/12/2010 -0600, you wrote:

Gentlemen,

I'm getting ready to pull the first rivets within the next
couple of weeks. I've been reading the Vans Air Force Forum lists on
pro-seal, automotive primers, or chromates and have found a variety of
opinions. It's not my intent to start a controversial discussion, but would
like to hear your opinions as to the best quality (something that will hold
up over time) and efficient method of sealing seams/rivets. In addition,
are there any techniques for your preferred method that would make my work
easier?



Happy New Year

Jerry Folkerts

SR2500 #093

Hi Jerry There's probably as many answers to your question as there are
builders. It depends on how you're going to use and store your plane, where
you live, whether you plan to go on floats and if on floats will they see
salt water. When I built my rebel I followed MAMs recomendations and
cromated all joining surfaces while the cromate was still wet. I also
dipped every rivet. If I were to build again I don't think I'd bother
dipping the rivets. On the cabin roof I think I would use sikaflex 1A and
dip those rivets in sikaflex to prevent leaks when outside in the rain. My
rebel has a couple small leaks in the roof but I'm normally in a hangar so
it's not much of a problem. I mixed small batches of cromate by using
syringes to measure the ratios and brushed on the cromate just before
riveting using disposable brushes that I made by cutting up sponges and
using a clothes pin for a handle.
Drew



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[Bob Bjorn]

Hi Jerald, I've been working on my Elite now for about 7 years and in
the last year or so have been unable to get zinc chromate, apparently due to
health concerns here in Canada. However the aviation supply houses now have
Zinc Phosphate instead. It doesn't lift the zn/cr when there is an overlap
area and it doesn't make you cough when being sprayed.( better healthwise)
Spray some in a small container, ie. spray can cap, to dip the rivets when
pulling. Dip and place a dozen or so then pull them while they are still
'wet'. Works for me.
Then I got kind of POed with the spray can thing. Another local very
studious builder found an automotive primer that the home built inspector
was completely happy with.
It is GLISTEN PC from Resto Motive, a division of Por-15 Inc. It's a
2 part primer that I proportion with a couple of small syringes, briefly mix
and brush on with an acid brush. In the right temperature it sets up in
about 15 min. Longer in the cold. If mixed in a small coverable contianer
it'll last for a few days for dipping the rivets. If not used frequently
the brush will go hard and need to be relegated to the 'round file'.
Using this procedure I have wound up with a lot neater job. I only
prime the mating surfaces as I've seen too many old aicraft with the area
zinc chromate peeling.
Hope I haven't given you a 'bum steer' on this but,again, it works for
me.
Bob
Bjorn Elite 710E




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[montanafloat]

I don't generally get into these conversations, but as nobody has brought it
up there is one thing to consider when using chromate or whatever between

All the mating surfaces, and rivets, that's the electrical ground. If you
use the airframe for ground return it may not be the best.

A bonding strap from the battery to the engine and back to a ground stud on
the firewall for other grounds, along with grounding your battery to the
airframe,

May save some grief later on. I do know that it helps considerably for
starter cranking power, and the avionics.

Remember a electrical circuit is only as good as the ground return.

My 2 cents worth take it for what it is worth.

Keith Kinden



_____

From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Bob
Bjorn
Sent: Thursday, December 30, 2010 10:32 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Pro-Seal, Primer, or Chromate



Hi Jerald, I've been working on my Elite now for about 7 years and in
the last year or so have been unable to get zinc chromate, apparently due to
health concerns here in Canada. However the aviation supply houses now have
Zinc Phosphate instead. It doesn't lift the zn/cr when there is an overlap
area and it doesn't make you cough when being sprayed.( better healthwise)
Spray some in a small container, ie. spray can cap, to dip the rivets when
pulling. Dip and place a dozen or so then pull them while they are still
'wet'. Works for me.
Then I got kind of POed with the spray can thing. Another local very
studious builder found an automotive primer that the home built inspector
was completely happy with.
It is GLISTEN PC from Resto Motive, a division of Por-15 Inc. It's a
2 part primer that I proportion with a couple of small syringes, briefly mix
and brush on with an acid brush. In the right temperature it sets up in
about 15 min. Longer in the cold. If mixed in a small coverable contianer
it'll last for a few days for dipping the rivets. If not used frequently
the brush will go hard and need to be relegated to the 'round file'.
Using this procedure I have wound up with a lot neater job. I only
prime the mating surfaces as I've seen too many old aicraft with the area
zinc chromate peeling.
Hope I haven't given you a 'bum steer' on this but,again, it works for
me.
Bob
Bjorn Elite 710E




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[Ron Shannon]

Unlike Keith, I _always_ get myself into conversations I usually know
nothing about. So to be consistent....

In 254R, the airframe is not used as a ground for anything. Zip, zero,
zilch. The port NAV lights share a ground wire with the pitot heat from the
top of the strut on in, and some LED panel annunciators share a ground, but
otherwise, there are no shared ground wires either. I forgot to mention that
significant fact when reporting 254R's empty weight a few months back,
but.... I could have saved a pound or maybe two but all the
electric-powered stuff works well with low resistance grounds, no ground
loop-transmitted noise, etc. IMHO, good use of a lb. or two.

It may be worth adding to this thread a reminder that allodining is another
anti-corrosion process in our quivers. (My expert-airplane-painter neighbor
allodines everything he possibly can before continuing with epoxy primers.)
I've allodined several parts that I don't want to paint. Examples include
the diamond plate brake/rudder pedals and the rear baggage wall, which has
auto carpet glued onto it with a spray adhesive.

Ron
254R



On Fri, Dec 31, 2010 at 2:26 PM, montanafloat <keith@montanafloat.com>wrote:

I don't generally get into these conversations, but as nobody has brought
it
up there is one thing to consider when using chromate or whatever between

All the mating surfaces, and rivets, that's the electrical ground. If you
use the airframe for ground return it may not be the best.

A bonding strap from the battery to the engine and back to a ground stud on
the firewall for other grounds, along with grounding your battery to the
airframe,

May save some grief later on. I do know that it helps considerably for
starter cranking power, and the avionics.

Remember a electrical circuit is only as good as the ground return.

My 2 cents worth take it for what it is worth.

Keith Kinden

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[Ken]

Great question! Grounding/bonding is primarily through rivets and
dipping them will generally INCREASE the electrical bonding integrity.
Perhaps not intuitive, but dipping does not prevent metal to metal
contact of the rivet. It does fill voids and keep moisture out of the
rivet joint which maintains the integrity of the joint. No dipping means
that moisture and a tiny tiny film of aluminum oxide (an insulator)
gradually increases the resistance of the joint leading to problems in
years to come. This is exactly the same reason why electrical joints
need to be gas tight when crimped or bolted for long life. (Same reason
that aluminum wiring has a bad rap unless no-ox and tight connections
are used). Without a gas tight joint you will be periodically cleaning
and refastening the connections. So I highly recommend dipping all
rivets. For rivets that weren't dipped, I recommend using corrosion-x
after painting but that does tend to weep for years. I've removed
thousands of dipped rivets without problems. Personally I judge
allodining to not add value to a 6061 airframe that will be painted but
that's a different discussion for another year.

happy New Year guys
Ken

Ron Shannon wrote:

Unlike Keith, I _always_ get myself into conversations I usually know
nothing about. So to be consistent....

In 254R, the airframe is not used as a ground for anything. Zip, zero,
zilch. The port NAV lights share a ground wire with the pitot heat from the
top of the strut on in, and some LED panel annunciators share a ground, but
otherwise, there are no shared ground wires either. I forgot to mention that
significant fact when reporting 254R's empty weight a few months back,
but.... I could have saved a pound or maybe two but all the
electric-powered stuff works well with low resistance grounds, no ground
loop-transmitted noise, etc. IMHO, good use of a lb. or two.

It may be worth adding to this thread a reminder that allodining is another
anti-corrosion process in our quivers. (My expert-airplane-painter neighbor
allodines everything he possibly can before continuing with epoxy primers.)
I've allodined several parts that I don't want to paint. Examples include
the diamond plate brake/rudder pedals and the rear baggage wall, which has
auto carpet glued onto it with a spray adhesive.

Ron
254R



On Fri, Dec 31, 2010 at 2:26 PM, montanafloat <keith@montanafloat.com>wrote:

I don't generally get into these conversations, but as nobody has brought
it
up there is one thing to consider when using chromate or whatever between

All the mating surfaces, and rivets, that's the electrical ground. If you
use the airframe for ground return it may not be the best.

A bonding strap from the battery to the engine and back to a ground stud on
the firewall for other grounds, along with grounding your battery to the
airframe,

May save some grief later on. I do know that it helps considerably for
starter cranking power, and the avionics.

Remember a electrical circuit is only as good as the ground return.

My 2 cents worth take it for what it is worth.

Keith Kinden

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