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Old 01-01-2005, 09:07 PM
JohnJacobsen's Avatar
JohnJacobsen JohnJacobsen is offline
Join Date: Jan 2005
Location: Taylor, TX
Posts: 98
Default Epoxy primer vs zinc chromate

I recently ordered the RV7 tail, and have been trying to decide on primer. Has anyone just used zinc chromate spray cans. That would make things simple but I figure epoxy will be more durable. I'm leaning towards epoxy. That brings up another problem, which one to use? Does Vans sell any? Havent seen it on the site if they do. Any input will be appreciated.

John Jacobsen
RV7 tail ordered

Chomping at the bit and ready to get started :-)
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Old 01-01-2005, 09:12 PM
admin admin is offline
Join Date: Dec 2004
Location: Dallas, Texas
Posts: 78

Hi John,

I had great success with MarHyde self-etching primer on my RV-6.
I found it at English Color stores:
Available in a rattle can. Pricey but VERY easy to use on small parts.

Doug Reeves
Owner: Delta Romeo, LLC.

Last edited by admin : 01-01-2005 at 09:18 PM.
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Old 01-01-2005, 09:33 PM
plaurence plaurence is offline
Join Date: Jan 2005
Posts: 74


If you live in a high humidity climate you might consider protecting the Aluminum from filliform corrosion,(the one that looks like a worm is eating the aluminum just under the paint.)

This is best done by:
1.etching with phosphoric acid(Alumiprep)
2.chromic acid converting (Alodine, iridite, etc) and
3. Priming with a milspec two part epoxy primer(MIL-P-23377D)This is a epoxy polyamide, strontium chromate.

The sounds like a lot of work, and it is. But living in South Florida, the aluminum surfaces will show corrosion in about three to four years.

Peter Laurence
RV9A Fuse
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Old 01-01-2005, 09:41 PM
hngrflyr hngrflyr is offline
Join Date: Jan 2005
Location: eugene, oregon
Posts: 206

Which ever product you use, it's most important to properly prep the surface for primer.

I've used both zink chromate and epoxy primers. They seemed to perform equally well. I would go where I could save a dollar or two.

I have a Cessna 120 as well as a RV-6. Last spring at the Cessna's annual inspection, I removed the steps from the gear legs for the first time since the plane was manufactured in 1946. The zink chromate primer under the steps was still intact.
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Old 01-02-2005, 11:37 AM
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JohnJacobsen JohnJacobsen is offline
Join Date: Jan 2005
Location: Taylor, TX
Posts: 98

Thanks for the input. Thinkin Im gonna go with the easier rattle can zinc.

John Jacobsen
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Old 01-02-2005, 03:07 PM
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mike newall mike newall is offline
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Location: Yorkshire, England
Posts: 2,131

I have used a 2 part non epoxy product that is an etch primer. It is marketed as Tetrosyl Autoprime in the UK and is excellent. I am sure a similar product is available from body shops in the US. I also use Acid 8 rattle cans, similar stuff, 1 part, goes on easy, no problems with masks etc.
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Old 01-02-2005, 07:00 PM
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Thermos Thermos is offline
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Location: KASH
Posts: 543

I used the Tempo zinc chromate to prime a few parts in my rudder. These parts had been prepped for good adhesion, but the zinc chromate still wore off in a few places during back-riveting. It's easier than the two-part epoxy primer I normally use, but not as durable.

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Old 01-03-2005, 09:34 AM
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Barry Barry is offline
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Posts: 112
Default Primer Info

I used the Dupont Variprime. Easy to ues and worked ok for me.

Here is some various information primers you might like to look at.

Hope this works as it is my first try at posting with this new forum!

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Old 01-06-2005, 07:34 PM
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JohnJacobsen JohnJacobsen is offline
Join Date: Jan 2005
Location: Taylor, TX
Posts: 98

Ok I decided to use the DuPont VariPrime. Wanted to go for the more durable and longer lasting. I found it at Car Quest Paint. Thanks everyone for the input.
John Jacobsen
RV7 Flying "Aluminum Falcon"
Zenith CH750 (Scratch building) SOLD
Locost 7 (Lotus 7 replica)
Taylor TX

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Old 01-06-2005, 10:45 PM
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n2prise n2prise is offline
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Location: Palm Bay, FL
Posts: 420
Default Self-etching primers...


Did you read the part in Van's plans book about the oils that are in the alclad aluminum sheets from the rolling mill? The self-etching primers get through that and give a good bond to the metal. The ribs are bare aluminum and will need the protection most of all. Van's mentions a Sherwin-Williams wash primer in the front of the plans book and it worked well for me. I mix it up in a 1-2-3 ratio. The 2 and 3 parts are the Sherwin-Williams chemicals.

The 2 parts is the industrial wash primer P60 G 2, the GREEN stuff with chromium zinc oxide, epoxy polymer, and other stuff in it. The 3 parts of the mix is the R7 K 44 wash primer catylyst reducer, phosphoric acid, MEK, etc. And the 1 part is just lacquer thinner to help it dry faster and not clog up my HVLP sprayer.

For a full load going into the sprayer, I mix up 100 ml of lacquer thinner, 200 ml of the GREEN stuff from the gallon paint can, and 300 ml of the acid from the gallon plastic jug. If you get this stuff from Sherwin Williams, you will need to buy 2 plastic jugs of R7 K 44, and only ONE gallon paint can of the P60 G 2.

ALL this kind of stuff is hazardous to your health, so be sure to wear a good carbon filter respirator and have a clean shave to insure that the mask seals good against your face. Wear good nitrile gloves or other chemical resistant disposable gloves and work in a well-ventilated environment away from any gas furnace or water heater. If you look at my web site, you will see that I always worked out on the driveway using plenty of Van's packing papers to keep the stuff off the driveway.

Check out this priming session on October 11, 2003 to see what I am talking about.

Good luck with your project and make it last a lifetime, or until you sell it and build something newer!

Jerry K. Thorne
East Ridge, TN.
RV-9A N2PZ (Enterprise)

Last edited by n2prise : 01-06-2005 at 10:48 PM.
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