Warbird Information Exchange

Hey guys

We have a ground up happening on a T-6, so I am trying to figure out if any manufacturers out there make any epoxy primers to match the yellow green primer on this part (goes in the gear well)
We have some Sherwin Williams #CM0724400, conforming to MIL-P-23377F that you can see on one side of the piece, but obviously is not a match. The original primer in the photo is not tinted, it is the yellow green. I know PTI makes a yellow green but are there any others that come close in shade?

Mark D

Just take the piece to an autopaint supplier & have them mix up a match.

_________________
Those who possess real knowledge are rare.

Those who can set that knowledge into motion in the physical world are rarer still.

The few who possess real knowledge and can set it into motion of their own hands are the rarest of all.

.and you can get it in water based so clean up is a snap -don't forget to Alodine first

_________________
Don't make me go get my flying monkeys-

Part of the "problem" is that NAA finish specs allowed green as well as yellow zinc chromate
primer. Having purchased numerous NOS parts for my SNJ from Lance (and Banaire, when they still
had them), the parts showed up (often in their original boxes / packing) in various shades of
green and/or yellow. I've read where it is suggested that NAA mixed the two colors as they
saw fit in order to spray/prime whatever they needed to get primed out in the factory that day.

I've also read where the Mil-Spec for the green zinc chromate changed after WW-II (went from
a darker green to a somewhat lighter green), so any NOS parts manufactured / procured after
WW-II may have a different/lighter shade of green on them.

The scale plastic modeling guys have debated this topic to death (maybe Google some scale
modeling pages / forums with some keywords; zinc chromate / primer / interior).

When I started tooling up to do my current project (a Stearman) I sifted through all my junk and came up with a pleasing sample of zinc chromate yellow, and then three or four samples of the green to have copied in polyurethane. I have wartime era samples of zinc chromate that are dam- near blue! I have read and tend to agree with the fact that there was no "specked" shade of green or yellow, however it turned out was however it turned out and the various manufacturers painted with it as they opened the cans. Don't forget that there were multiple suppliers of the product. If someone accused me of having the wrong shade of zinc chromate green in my airplane I'm afraid my response would have to be:

"Prove it."

Dan

_________________
Defending Stearmans on WIX since Jeff started badmouthing them back in 2005.

Hi Mark,

I've had a similar search for the most suitable primer to replicate the original zinc chromate colours for my Wirraway project. The factory mainly used green primer as shown in your photos, but with some yellow primer as dictated by availability.

I'm just about ready to get primer in as the warmer months return to south-east Australia and I can finish off some of my parts. Two options have arisen as the most likely, mindful that I'm keen to achieve accurate finish with the least amount of coats yet not compromise protection against corrosion.

Talking to the local PRC-Desoto representative he's advised that BMS 10-11 spec primer does not need to be topcoated and can be tinted to the desired colour.

Another option is Randolph Epoxy Primer per the details at: http://www.randolphaircraft.com/epoxyprimer.html They make a dark green to supposedly represent wartime zinc chromate, this being tinted from their standard white product. It's interesting to note that they specify on the website that there's no need to topcoat over it when used internally.

The only other solution I've come across is to use a primer of any colour and then topcoat with a specially-matched paint. This gets rather time consuming though.

Would be very interested to hear if you come across any other options.

Cheers,
Matt

Hi,

This is what I can come up with, in regards to zinc chromate primer. Willie M, has a 1 gallon can of original zinc chromate. It is yellow in color and it matches close to the primer you dipped your part in. I have used some of it and it is really toxic to shoot.

Through my research, I have found that straight zinc chromate is "yellow" in color. A manual I have calls out for you to make "yellow green primer" by mixing 10 parts zinc chromate to 1 part "black enamel" and 1 part tolulene, for thinning. This will make the paint look green, just like the part in your picture.

The reason the colors vary.
1; Zinc chromate is just a primer, so it probably varied a lot from batch to batch.
2: Zinc chromate in its natural state is yellow, but all yellows are very transparent, so the tint can vary by what the base material is under the primer. ie; Brighter surface, brighter yellow, darker surface, darker yellow.
3; Yellow green primer was, most likely, hand mixed. So variance in color could happen real easily. We see it all the time in parts we purchase and airplanes that we restore.

Also, chromate seem to fall under different names. But this is what I have researched. You have straight zinc chromate, also some times called "chromate", which is yellow. And then you have yellow green primer that is also called green chromate or tinted chromate.

I use a white Dupont DP-40 (I think) epoxy primer. It's great stuff, it shoots nice and you don't have to scuff it for up to 5 days before you top coat it. And then I have the local auto paint and supply eye-match the yellow and green colors to sample parts that I have.

Hope this helps, this my first wix forum.

Bill

Welcome, Bill! And thanks for the first-hand insight!

kevin

_________________
FOUND the elusive DT-built B-24! Woo-hoo!!!