Monday, March 8, 2010

Primer, Pods, and Goofy Airplanes

What's That Green Mess All Over Your Airplane?

It occurs to me that some of the folks who read the meanderings found on this site are probably a little younger than I am, and therefore lack a certain perspective when it comes to building model airplanes. For example, there was a time, a very long time ago, when we knew next to nothing about what color to paint the cockpits of our models. A lot of them ended up being some variation of flat black as a result, and since we were largely building things that were in 1/72nd scale and that came with really thick transparencies to boot, you couldn't see in there anyway. You  could've painted your interiors purple and nobody would've noticed a blessed thing. Accuracy? What's that?

Then, somewhere around 1965 or 1966, we got educated. Official Paints (I think that was the name), Scalemaster, and Frontier HQ all came out with their version of a nasty, yellow-green primer they called "zinc chromate" and allowed as how you should paint the insides of your American models in that color. Those of us who belonged to the then-fledgeling IPMS jumped on that paint like a chicken on a Junebug (I'm from Dixie, ya'll, just in case you hadn't noticed before) and started painting everything we could with it. We all had something called "references", of course, but we generally only used them to figure out how to paint the outsides of the model. The insides, to include the cockpit area, ended up that vile green color. The horror!

We've come a long way since then, and mostly we all know (or know where to find out) what color to paint the insides of things, while Nasty Old Zinc Chromate has largely been replaced by epoxy primers in the world of real aviation. There was a big span of time, though, from the Second World War to the mid-1980s, to be exact, when zinc chromate ruled the roost in the world of American military aviation primers. It's there, it's ugly, and it's mostly misunderstood, so let's talk about it for a minute.

First, there's that zinc thing. The primer got its name because of its high content of powdered zinc, used to assist in corrosion control but primarily to provide a "tooth" for the topcoat of paint to adhere to. In point of fact there's so much zinc in a can of zinc chromate that it's noticeably heavier than an equal-sized can of anything else.

Then there's color. The stuff is indeed a nasty sickly pale greenish-yellow in one of its iterations, but therein lies the rub. (Somebody famous said that. It wasn't me.) There are, you see, two; count 'em; two color variations for the stuff. Both were produced to Mil-P-8585, but the yellow stuff was Mil-P-8585Y, while the Mil-P-8585T designation was assigned to a darker color that in theory matched FS595 34151, or ANA 611, affectionately known by most modelers as "interior green". It was meant to be applied in crew areas (unless a different color was specified, which mostly was the case after the end of WW2) but sometimes ended up in gear wells on on the interior surfaces of gear doors as well. (There must have been a lot of the "T" variation around, too, because the civil engineers at every base my dad was stationed at back in the 50s painted anything that wasn't nailed down with the stuff. Once again, however, we digress.)

Finally there's application. The 8585T was meant to go on in a solid color coat of uniform density. Not so The Nasty Y which, by Federal specification, was intended to go on in a single light but uniform coating sufficient to provide complete coverage. Not color coverage, just primer coverage. That means, my friends, that a properly-applied coat of yellow zinc chromate that will be visible on a model should have a splotchy appearance, and that means that you should apply it over silver or, just maybe, an uneven and streaky strawish color that simulates alodine, whichever one best simulates the way the real airplane looks. Whatever you undercoat with, your yellow zinc chromate should be splotchy. When properly applied either primer ended up having a semi-gloss finish, which I presume was a direct result of the reducers (thinners) used, but the sheen could run the gamut from full matte to full gloss, with everything in-between. It all depended on the guy mixing the paint for spraying.

As for where to get a color to use, a lot of the folks who make paint for our hobby produce "zinc chromate", and I'm not about to tell you which one is best. Look at the color shot of the F-4 below and you'll get a good feel for where you're heading with the stuff, 'cause even though there's variance (want to really whiz off the "instant expert" modeler you know? Challenge them on shades and tones of paint---the fun can last for weeks!) in shade it all pretty much looks like what's on the Phantom.

Confused? You shouldn't be, 'cause this is easy. Just make your primer spotchy most of the time to simulate a coating done to spec and don't paint your interiors with it, for cryin' out loud! Put it on using a photo of a real airplane as your guide and it's a simple thing, to be sure!

Here's something you can do with zinc chromate paint. There I was, standing at Last Chance at Bergstrom AFB and minding my own business, just trying to photograph all the stuff taxing out at RAM (Reconnaisance Air Meet) '88, when this guy came diddy-bopping by. It was an F-4E painted entirely in Mil-P-8585Y yellow zinc chromate primer, with no visible markings of any kind. It must've just left the Corrosion Control facility at some base or other; there's no other reason for the lack of paint. Pretty cool, huh? The photo's overall blotchy appearance is an example of properly-applied zinc chromate primer at its best.                                                                                                                                  Phillip Friddell

Even More Fun With Zinc Chromate. This 48th TFS/366th TFW F-4C was photographed at DaNang in March, 1968, while undergoing BDR (Battle Damage Repair) by members of a civilian team from Kelly AFB. (The fellow on the left is Ildofonso Gandara, who was kind enough to provide this shot.) Once you get past your amazement at the overall condition of the airplane, take a look at the blotches of zinc chromate that appear everywhere on the fuselage. Notice I said blotches because, even in this application, the color density isn't consistent. It's per spec.                                                                       Friddell Collection

Just Passin' a Little Gas

We've mentioned the Navy's use of buddy stores for aerial refueling a couple of times during the course of our never-ending discussion of the Hasegawa A-4C (the model thereof of which is still in prep for paint---a convoluted sentence, but a sentence nontheless!). Here's a drawing from a mid-70s Sargent-Fletcher (who made the things) catalog that shows details to some extent. As a reference point there's one of these hanging on the centerline of the Charlie that's tanking off the A-26 a few blogs back. It would be a neat addition to a model, for sure.

What in the World is an Interstate TDR-1?

Think cruise missile, but in a really formative state. They were used, but in an extremely limited manner, in the Pacific during WW2. I was looking for something else last night (the story of my young life) and I came across these shots. They may or may not be of interest to you, but they're unique enough for inclusion today.

Somewhere in the South Pacific...   This TDR-1 is apparently being readied for a mission. BuNo is 27878. Note the last 3 digits of the BuNo crudely applied to the vertical stabilizer. Of interest to those who might be tempted to build a diorama is the Quonsett hut  in the background and the highly-sophisticated ground support equipment.                                                                                                          National Archives

Getting ready to go out and ruin somebody's day! Here's "Edna III" (in yellow) being bombed up for a mission. Of particular interest is the suspension band under the bomb, and the loading ratchets being used by the armorers. The television camera that was an integral part of the guidance system is shown to advantage, as are the fixed-pitch wooden propellers. BuNo is unknown.                                                                                                                    National Archives

And that, my friends, brings us to the end of today's installment. Enjoy the rest of your day and we'll meet again soon.


I don't know why I didn't think of this when I should've, but go back up to that color photo of the F-4 and take a second look at Ildofonso Gandara. I met him at a place I used to work, and was immediately impressed by his kindness and candor. He was in charge of our QC department and had come to the company I worked for after retiring from a career at Kelly AFB. He was a gentle and kind man, and a friend to the world.

We were talking one day, he and I, and I asked if he'd served in World War 2. He grinned that Gandy Grin of his and shook his head ; yes, he'd been in the Army. I figured he'd been a mechanic of some sort, since aviation mechanics was his specialty, and put forth that notion to him. He grinned again and said no; he never had a chance to do that during the war. The next question was obvious: "What did you do?" He gave me a reprise of The Grin and said, in a voice so soft I had to strain to hear him, that he'd been a paratrooper and had jumped into Southern France when we invaded that part of the world in 1944.

The look on my face must have said it all, because he followed that up by telling me it wasn't much of a thing, because he was only there for three days before a German shot him in the stomach and he had to go back to the States. I asked him how he felt about being shot, and his answer could've summed up his entire generation: "I felt like I was letting the other guys down because I got to leave and they had to stay".

Twenty years later Gandy volunteered to go to Vietnam to fix F-4s. Nobody made him do it, but he went anyway, because he thought it was the right thing to do.

That was Gandy, and that was his generation. We can never repay the debt we owe those who served, and who serve today. We owe those folks, or at least I think we owe them. Thanks, ya'll, for what you did and for what you do. My hat is off to each and every one of you.

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