primer alternative

Murray & Carol · Post by **Murray & Carol** » Fri Feb 17, 2012 10:29 pm

Hi All

Has anyone come up with an alternative to Zinc chromate primer. This has to be the only dreaded part of building as the rest goes pretty well.

Thanks Murray Cherkas
REBEL 505

Ralph Baker · Post by **Ralph Baker** » Fri Feb 17, 2012 10:29 pm

Murray,
Sherwin Williams/Pratt & Lambert has a strontium chromate two part epoxy primer that I have been using. It still requires catalyzing & mixing but is a more modern alternative to zinc chromate. I have been told it is used her in SC at the Boeing facility. If your intent is to find a one part, out of the can and on the work product I am not aware of any.
Ralph Baker

Bob Patterson · Post by **Bob Patterson** » Fri Feb 17, 2012 10:29 pm

Hi Murray !

Zinc Chromate primer has been illegal in North America for
years (bad for the environment) !!

The Murphy factory recommends Polyfiber Epoxy Primer to bond
all components together. Almost every other aircraft manufacturer
has tested this stuff, and it IS <THE> best corrosion protection/
bonding agent out there ..... why not just use it ???

You can spray this primer on large areas, but it is not
really necessary with the 6061-T6 aluminum used in the Rebel.
It DOES the best job of corrosion protection if it is brushed on,
and the pieces assembled WET. For large areas, there are products
like Northern Shield and Boeing D-29 that can be sprayed in later,
if desired.

For the completed airplane, before final painting, USE THE
PRIMER THAT IS PART OF THE PAINT MANUFACTURERS "PAINT SYSTEM" !!!!
If you don't use ALL parts of the SYSTEM, your paint could likely
blister and fall off somewhere down the road - or bubble and separate
right away !!

What specific problem were you having with primer ??

......bobp

------------------------------------orig.------------------------------------
At 06:42 PM 10/17/02 -0600, you wrote:

Hi All

Has anyone come up with an alternative to Zinc chromate primer. This has to

be the only dreaded part of building as the rest goes pretty well.

Thanks Murray Cherkas
REBEL 505
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<BODY bgColor=#ffffff>
<DIV><FONT size=2>Hi All</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>Has anyone come up with an alternative to Zinc chromate
primer. This has to be the only dreaded part of building as the rest goes

pretty

well.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>Thanks Murray Cherkas</FONT></DIV>
<DIV><FONT size=2>REBEL 505</FONT></DIV></BODY></HTML>

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Murray & Carol · Post by **Murray & Carol** » Fri Feb 17, 2012 10:29 pm

Hello BOB

No problem with the primer. My concern is that it is so toxic. Thanks for
the info on using the right primer for the paint being used. And yes I did
use Endura over the zinc chromate primer on the inside of the fuselodge. On
the outside I am using RM brand with their primer .

I hope that the poyfibre epoxy primer you suggested is more people friendly.
As I am thinking of building another airplane, if there isn't a viable
alternative to the zinc ch. I will have second thoughts as to whether or
not to start a new project.

Thanks for all your help to myself and all the rest of us.

Murray Cherkas
REBEL 505

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Murray & Carol · Post by **Murray & Carol** » Fri Feb 17, 2012 10:29 pm

Hello Ralph

Thanks for the info. I'll look into this as an alternative.

Murray Cherkas
REBEL 505

Mike Davis · Post by **Mike Davis** » Fri Feb 17, 2012 10:29 pm

Murray

Sorry I couldn't get this out sooner, my ISP seems to be having problems.

The priming part should not be a big deal except for the time/setup

required

to apply the paint. We are doing our first wing and we are much less
enthused about doing the wet wing sealant routine!

For our Elite project we have chosen a Dupont product called Corlar 810R
which is a "filling wash primer". It is a simple 1:1 ratio, 2 part
material which contains chromate and also claims to etch the base material
(before it dries). There is a non-chromate version as well. I believe a
modern product like this is a good choice especially compared to the old
zinc chromates of the past. It can be had at your local automotive body
shop supplier like UAP/NAPA, we apply it using a decent retail store
(non-bleeder) spray gun.

I contacted Dupont for their recommendation on materials and this was

their

choice for the application. It is also used by an aircraft painting shop
not far from me so I am confident it will be acceptable. For top coating,
like on the outside of the aircraft, it should be followed by Dupont
1044R high solids primer and Imron (the polyurethane topcoat). As Bob has
reminded us always stick with a unified paint system from a single
manufacturer to avoid incompatability problems.

If you use this material and these days many paint systems, you MUST use a
fresh air system as the typical (carbon) filter mask will not remove
dangerous vapors (isocyanates etc.) from the air. I have a full face

window

type of "helmet" which is excelent for those like me who wear
glasses. I built a fresh air blower for very few $ using a central vac

type

blower and the plywood from one of the shipping crates, you can see it
at our project site (www.elite583.cjb.net) under Other Details.

We have a differing opinion from MAM about the Polyfibre material shipped
with the kits, it is not a chromate and it does not etch the base
material like the Corlar and we do not subscribe to the apply wet & use it
as an adhesive for a couple of reasons. There is no guarantee that the
material will still be wet when you have painted all the mating surfaces
when you assemble something (like a wing we are working on right now)
and I have some doubt that the paint will remain stuck even after it dries
given that the parts will flex to some extent during their life. If I was
designing a structure like an airplane I would be conservative and NOT
depend on the "untrained" builder to achieve a good bond with the paint
so I would design the plane as if it was not there and any gain would be a
bonus. I would expect MAM followed this approach since for example
the riveted joints are "overdesigned" to account for "untrained" builder
errors.

I also prefer to follow the practise of Cessna who, according to their

tech

rep. whom I spoke with, paint the parts prior to assembly. We dip the
rivets in Corlar prior to installing them as well.

I know I am taking an approach different from what Bob P. & the factory
recommends but since we are homebuilding for the "purpose of
learning by experimentation" (EAA) we will not always make the same
decisions and your decision must be made by weighing all of the
information you have available and deciding what is right for you. Our
location close to the ocean and possibility of going on floats had an

impact

in our choices.

Hope this hasn't added to the confusion!

Cheers

Dave R.
Francine D.
Elite583.cjb.net

Murray & Carol wrote:

Hi All Has anyone come up with an alternative to Zinc chromate

primer.

This has to be the only dreaded part of building as the rest goes pretty
well.Thanks
Murray CherkasREBEL 505

--
David A. Ricker P. Eng.
DARTEC Engineering Inc.
Fall River, Nova Scotia
Canada

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klehman · Post by **klehman** » Fri Feb 17, 2012 10:29 pm

Hi Murray

What's toxic?
Polyfiber no longer has chromates. The rest is pretty benign I
thought... I know I avoid MEK and alodyning but I don't mind the epoxy?

FWIW I would not hesitate to substitute another epoxy primer that is
recommended for aluminum. Think the Rand products are a lot cheaper
around here.

The fact that you can freeze the stuff for up to a couple of weeks sure
cuts the wastage.

Ken

Murray & Carol wrote:

Hello BOB

No problem with the primer. My concern is that it is so toxic. Thanks for
the info on using the right primer for the paint being used. And yes I did
use Endura over the zinc chromate primer on the inside of the fuselodge. On
the outside I am using RM brand with their primer .

I hope that the poyfibre epoxy primer you suggested is more people friendly.
As I am thinking of building another airplane, if there isn't a viable
alternative to the zinc ch. I will have second thoughts as to whether or
not to start a new project.

Thanks for all your help to myself and all the rest of us.

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klehman · Post by **klehman** » Fri Feb 17, 2012 10:29 pm

I gather self etching primer is a nice product at controlled thickness
on an outer surface. I have always been curious though as to what stops
it from etching too much if you happen to get a very thick layer of it
in a seam or joint? I've heard rumours of problems but never any
substantiating evidence.
Ken

Mike Davis wrote:

Murray

Sorry I couldn't get this out sooner, my ISP seems to be having problems.

The priming part should not be a big deal except for the time/setup
required

to apply the paint. We are doing our first wing and we are much less
enthused about doing the wet wing sealant routine!

For our Elite project we have chosen a Dupont product called Corlar 810R
which is a "filling wash primer". It is a simple 1:1 ratio, 2 part
material which contains chromate and also claims to etch the base material
(before it dries). There is a non-chromate version as well. I believe a
modern product like this is a good choice especially compared to the old
zinc chromates of the past. It can be had at your local automotive body
shop supplier like UAP/NAPA, we apply it using a decent retail store
(non-bleeder) spray gun.

I contacted Dupont for their recommendation on materials and this was
their

choice for the application. It is also used by an aircraft painting shop
not far from me so I am confident it will be acceptable. For top coating,
like on the outside of the aircraft, it should be followed by Dupont
1044R high solids primer and Imron (the polyurethane topcoat). As Bob has
reminded us always stick with a unified paint system from a single
manufacturer to avoid incompatability problems.

If you use this material and these days many paint systems, you MUST use a
fresh air system as the typical (carbon) filter mask will not remove
dangerous vapors (isocyanates etc.) from the air. I have a full face
window

type of "helmet" which is excelent for those like me who wear
glasses. I built a fresh air blower for very few $ using a central vac
type

blower and the plywood from one of the shipping crates, you can see it
at our project site (www.elite583.cjb.net) under Other Details.

We have a differing opinion from MAM about the Polyfibre material shipped
with the kits, it is not a chromate and it does not etch the base
material like the Corlar and we do not subscribe to the apply wet & use it
as an adhesive for a couple of reasons. There is no guarantee that the
material will still be wet when you have painted all the mating surfaces
when you assemble something (like a wing we are working on right now)
and I have some doubt that the paint will remain stuck even after it dries
given that the parts will flex to some extent during their life. If I was
designing a structure like an airplane I would be conservative and NOT
depend on the "untrained" builder to achieve a good bond with the paint
so I would design the plane as if it was not there and any gain would be a
bonus. I would expect MAM followed this approach since for example
the riveted joints are "overdesigned" to account for "untrained" builder
errors.

I also prefer to follow the practise of Cessna who, according to their
tech

rep. whom I spoke with, paint the parts prior to assembly. We dip the
rivets in Corlar prior to installing them as well.

I know I am taking an approach different from what Bob P. & the factory
recommends but since we are homebuilding for the "purpose of
learning by experimentation" (EAA) we will not always make the same
decisions and your decision must be made by weighing all of the
information you have available and deciding what is right for you. Our
location close to the ocean and possibility of going on floats had an
impact

in our choices.

Hope this hasn't added to the confusion!

Cheers

Dave R.
Francine D.
Elite583.cjb.net

Murray & Carol wrote:

Hi All Has anyone come up with an alternative to Zinc chromate
primer.

This has to be the only dreaded part of building as the rest goes pretty
well.Thanks
Murray CherkasREBEL 505

--
David A. Ricker P. Eng.
DARTEC Engineering Inc.
Fall River, Nova Scotia
Canada

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Rob Luce · Post by **Rob Luce** » Fri Feb 17, 2012 10:29 pm

I've helped on a couple Zenith's (which also use 6061), and the builder's
have either used "automotive" self etching primer, or no corosion protection
at all (no zinc chromate, etc).

The other substances that I've read being on the Zenith list are zinc
chromate, zinc oxide, zinc phosphate, "self-etching primer", and a couple
marine products. Probably the most helpful suggestion that I've heard is to
go into a marine supply shop and ask what they have for a particular
material (the stuff they use for aluminum is different than steel (engine
mount, etc) on a boat).

The other item that I've read is that the zinc does the work. Chromate, is
supposedly the poisonous stuff.

My experience with the self-etching primer is that it didn't seem to have
any negative effect on the aluminum, but on the planes where this was used,
primer was used lightly (as in, just enough to cover, not coat, you could
easily see the lettering through the primer).

My comment: This is 6061, it's not going to be as prone to corrosion as a
aluminum that has copper or another material that will cause a galvanic
response. There is a posibility of some interaction between the rivets and
the aluminum, but that's pretty remote. There are planes over 30 years old
now that have built with the materials and processes that we use now, and
are still flying. One of the more famous is Chris Heintz's original
homebuilt, 6061 with stainless steel rivets, bare aluminum, no zinc
chromate. It's been sitting outside for ~25 years, and still doesn't have
any corrosion, according to Chris.

So, do what makes you feel comfortable. But I wouldn't poison yourself just
to try to protect 6061.

I'll be using self-etching primer, at this point, unless I find out
something to the contrary.

Rob Luce
Rebel tail on order

----- Original Message -----
From: "klehman" <klehman@albedo.net>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, October 20, 2002 11:30 AM
Subject: Re: Primer Alternative

I gather self etching primer is a nice product at controlled thickness
on an outer surface. I have always been curious though as to what stops
it from etching too much if you happen to get a very thick layer of it
in a seam or joint? I've heard rumours of problems but never any
substantiating evidence.
Ken

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Murray & Carol · Post by **Murray & Carol** » Fri Feb 17, 2012 10:29 pm

Hello Dave & Francine

Thanks for the reply.
FYI
I also may someday be on floats in salt water. Spoke to Brian at MAM. What I
ended up doing was to etch, alodine and prime with zinc chromate primer the
whole skin,same with the bulkheads. Let dry then put on SIKOFLEX 1A between
the mating surfaces, used lots of cleco's to pull the surfaces tight
together, pulled the rivets slowly also to squeeze out the sikoflex. I did
this on my fuselodge only. This gives me a waterproof joint as well as helps
bond the joints together.
This was my decision which may differ from another well thought out idea.

Good Luck
Murray Cherkas
REBEL 505

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Bob Patterson · Post by **Bob Patterson** » Fri Feb 17, 2012 10:29 pm

Hi Murray !

The toxicity is the reason the government banned zinc chromate,
I guess. While the Polyfiber Epoxy Primer is certainly less nasty,
and is relatively harmless if brushed, like all epoxies, it can
be deadly if sprayed and inhaled. A positive pressure fresh air
breathing system is the only safe way to work with any of these
paints.

I've used the RM paints on another Rebel, and plan to use
it on this one soon - it's good stuff ! I used the "middle" grade -
now called UNA, I believe. It's a 2 part enamel that gives a durable
glossy finish at reasonable cost... I'm sure you'll have good
results with it, with a HVLP sprayer.

By all means start another project !! Maybe a Super Rebel this
time ???!!! Take time out to fly your Rebel, though - how about
joining us on next year's Rebel Ramble ??? We're going to the West
Coast in July, and the East Coast in August !! :-)

.....bobp

----------------------------------orig.--------------------------------
At 08:15 PM 10/19/02 -0600, you wrote:

Hello BOB

No problem with the primer. My concern is that it is so toxic. Thanks for
the info on using the right primer for the paint being used. And yes I did
use Endura over the zinc chromate primer on the inside of the fuselodge. On
the outside I am using RM brand with their primer .

I hope that the poyfibre epoxy primer you suggested is more people friendly.
As I am thinking of building another airplane, if there isn't a viable
alternative to the zinc ch. I will have second thoughts as to whether or
not to start a new project.

Thanks for all your help to myself and all the rest of us.

Murray Cherkas
REBEL 505

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