Primer On Priming
I have heard of many different methods of priming airplane parts.
I decided to keep a journal of what people are doing...

May 4, 2003 - I have decided to go with Du Pont Variprime 615S & 616S. This product is available locally and I have been advised by someone I know who has built many airplanes that this is what they have used very successfully. DCP_1252.1.jpg (140933 bytes)
Ken Scott of Van's ( "Some primer recommendations are mentioned in the preview
plans...almost every manufacturer has a suitable product in their
line.  There are probably a million words about primer on the
internet but it all boils down to whatever's conveniently available to
you. Many of us don't bother with it at all."
George & Becki Orndorff at GeoBeck, Inc. - Texas Dupont VariPrime, parts number 615 and 616.   It is self-etching and you only need a thin coat.  We clean the surface before priming with laquer thinner.

May 5, 2003  - Variprime is a self-etching primer and the use of it alone is sufficient.   We clean the parts with laquer thinner and then spray a thin coat of Variprime.  You should be able to read any markings on the aluminum through the Variprime coat.  There is no need to rough up the surface with scotchbrite first.   That would destroy the alclad.  There is no need to alodine or any other treatment before or after spraying with Variprime (except finish painting pieces that will show).

Gary Newsted - New Hampshire I have used Dupont VeriPrime 615S self-etching primer on many projects for many years.   I swear by it and wouldn't consider any other product.  It comes in heavy metal chromate, or a new type of environmentally-friendly brew.   I've always used the chromate myself.   Just use it wisely. 

Pick up a gallon to start. You'll need at least three before you're done, but one will get you through the empennage and into the wings.   Dupont products are available at most good automotive paint stores.  Make sure you're seated when they tell you how much paint costs.  It gets even more expensive as you get into finishing paint!  The VeriPrime is a two-part paint, so for every gallon of primer you'll end up with two gallons sprayable after mixing the activator %50/50.  

Get a gallon of Lacquer Reducer for cleanup, and a quart of PrepSol for final surface cleaning.   I like to ask for an empty gallon paint can and lid for disposing unused materials.  Be careful what byproducts you mix, I've seen chemical reactions that heated the can so much I had to use gloves to get it outside. Avoid spontaneous combustion and properly dispose of this stuff.  

Also pick up a full carton of ScotchBrite Pads 07447.  You'll easily use these, so get the big box.  I like to cut these in half and run them in my electric hand sander for flat surface prep.

Some crazies have tried to use spray-bombs throughout the entire project.   Personally, I have trouble getting through one spray-bomb without clogging the tip.   This is not a shortcut worth taking.  It's more expensive and the results are inferior.   Use quality paint and equipment.

Robert Scott - California Alodined all internal parts and painted with FR Prime. We had a gallon of this at work that just expired and were going to dispose of it. In case you don't know FR Prime is a two part green primer per DMS 2143, the stuff Boeing uses on their parts. It has a shelf life for one year when certifications are needed.
Andy Karmy - Washington The primer I am using is a Waterborne 1 part Polyurethane primer sealer. It's non self etching & requires a separate Etch step before spraying. Check out their products at Aircraft Finishing Systems

In talking with Paul (the owner of AFS) he said that the epoxy was a great primer... The definition of "primer" is a substrate to hold the surface paint onto the metal. It is very porous so that the top coat bonds good to it. The primer sealer has a bit of poly top coat mixed into it so it gets just a bit more of a shine (not much) and seals the surface to moisture penetration and other contamination. Also it's so easy as you have just 1 part to use.

Don Alexander - Virginia

Given the toxicity of zinc chromate I had second thoughts about using it. I wanted to live long and prosper after finishing the building process so I could fly for years. There's a Sherwin Williams self etching primer #988 that I ended up using. Initial product was purchased from NAPA in cans under their label. The spray nozzel is far and away the finest I've ever seen on a can of spray paint and the material seem durable. Preperation has been to scotch brite parts thoroughly and degrease, then spray. Generally the coat is light enough you can still read the Sharpie pen markings I've made on the parts. So far I'm pleased.

Chris Heitman - Wisconsin I am using an epoxy primer that meets MIL-P-23377 Rev. F Type I Class 1. I obtained this from PRC-DeSoto (a division of PPG). I ordered it from their Indianapolis sales office: (317)290-1600. The primer base is part number 513X390 and the activator is part number 910X624. These both come in gallon containers ($89.78 for a 2 gallon kit). They also suggest adding a special (very expensive) thinner before spraying which is part number 020X411 ($69.95/gal). The mix ratio is 4:4:1 by volume (base/activator/thinner). Their minimum order is $100. I heard a rumor that this epoxy primer may be discontinued because of EPA rules on VOC's so I ordered a second kit to make sure that I have enough to finish the airframe. It only has a 1 year shelf life so I have to work fast! (I have the extra kit in the refrigerator to help extend the shelf life - much to my wife's dismay!) It looks like a single 2 gallon kit would fall slightly short of completing the airframe interior. I am applying the primer with a Sharpe Cobalt HVLP spray gun. When priming the interior surfaces of the skins, I put a heavier primer coat along the rivet lines where the skin would be in contact with the underlying structure. However, in order to save weight, the remainder of the internal skin surface receives only a very light coat. Only a thin, semi-transparent coat is required to meet the Mil Spec for corrosion resistance (optimum film thickness is 0.6 to 0.9 mil). One more reminder: you need to let the primer sit for 30 minutes after mixing the components before beginning to spray.
Todd Houg - Minnesota I used PPG products two part wash primer, DX1791 and DX1792. This is a self etching wash primer that PPG claims provides excellent corrosion resistance. PPG recommends abrading the surface prior to application with etching optional. For preparation, I used a a combination of PPG DX-330 wax and grease remover, lacquer thinner and Scotchbrite pads. I first cleaned the aluminum with DX-330, although I used lacquer thinner on the blue markings to get them off easier. I then scruffed the surface with Scotchbrite pads to maximize the primer adhesion. Then, as I laid the parts out for priming, I gave them a final wipe down with DX-330 to remove any oils from handling.