1/18 Scale Blue Box F4U-1A Corsair Modification

[Oldbaldguy]

1 hour ago, JayW said:

 

 

 

Would love to find some etching primer that is ZC yellow.

 

Try www.aircraftspruce.com and type zinc chromate into their search bar.  They list several versions and colors of aviation grade self etching primer in rattle cans.  If that address doesn’t work, just google Aircraft Spruce and Specialty and you’ll find ‘em.  These guys have just about anything you could ever imagine you’d need for an airplane, large or small.  Really good people.

[chuck540z3]

26 minutes ago, Oldbaldguy said:

Try www.aircraftspruce.com and type zinc chromate into their search bar.  They list several versions and colors of aviation grade self etching primer in rattle cans.  If that address doesn’t work, just google Aircraft Spruce and Specialty and you’ll find ‘em.  These guys have just about anything you could ever imagine you’d need for an airplane, large or small.  Really good people.

 

Or, use one of the many MRP Zinc Chromate Yellow shades like this one, easily purchased through Sprue Bros.

 

MRP 129

 

Cheers,

Chuck

[JayW]

18 hours ago, Oldbaldguy said:

Try www.aircraftspruce.com and type zinc chromate into their search bar.  

 

Thanks OBG.  I see one on that site that seems to be ZC yellow colored although it is described as "green".  Think I will order some.  There is also another self-etch in there that looks to be yellow, but is not available in rattle can.  Don't want that. 

 

18 hours ago, chuck540z3 said:

Or, use one of the many MRP Zinc Chromate Yellow shades like this one, easily purchased through Sprue Bros.

 

Hi Chuck.  Beautiful looking stuff for sure.  You know I have a couple of bottles of Tamiya XF-4 yellow green.  Now that I have an airbrush (somebody absolutely insisted that I get one) I know I can thin it down and spray it.  Which I will do.  However, we are talking self-etch primer for the bare aluminum surfaces on the Corsair, and that is a different animal.

 

In my past profession (aircraft structural engineer designer), I learned early on that surface preparation is a science unto itself.  MOF - to get a drawing approved for production, one step was to get a sign-off (there was a space in the title block for signature) from the Materials & Processes (M & P) engineering rep, which included among other things surface preparation expertise.  The main purpose of surface prep is to protect the surface from elements that would compromise the purpose of the surface (namely corrosion or radiation from the sun), and to prevent oxidation of the surface metal.  A secondary purpose is appearance - to provide color or other marking.  Duh.  We all know that.  What not all of us knows is that bare metallic surfaces (in this case aluminum) do not offer great adhesion for paints (primer or top coats).  It flakes off.  Primers provide adhesion for top coats, but do not necessarily adhere well to metallic surfaces.  So the trick is to get a primer to stick well to aluminum.  In the world of aircraft this is done by first applying a surface treatment - for aluminum either anodizing or chromate conversion coating (alodine).  Something else for ferrous alloys.  Anodize for bare aluminum, alodine for "clad" aluminum, where clad means a thin coating of pure aluminum (as opposed to alum alloy) on the outer surface.  Incidentally it is the "clad" surface that allows the mirror surface polishing to be possible, and it is actually a decent protective layer itself - that is why we see it often on aircraft skins.  But to paint it, first there must be a surface treatment.  Either surface treatment (anodize or alodine) adheres very well to the aluminum surface, and provides a good surface for primer adhesion.  Top coat paints used in the industry, in general, are formulated to adhere well to primers, but not the surface prep.  So, the proper way to paint aluminum panels is first to do some sanding, then anodize (or alodine), then primer (usually zinc chromate), and then an enamel top coat. 

 

In modeling, it is the surface appearance we are interested in, not protection from the elements.  But adhesion is still important.  If we are skinning with aluminum, and a surface prep like anodize or alodine is not present, as is the case with my skinning effort (or Peter Castle's or anyone else who is skinning models), then something must be done to provide good paint adhesion.  Otherwise, paint will come off when we mask (a disaster).  In the industry, field repair finish procedures cannot use a complicated factory process, and instead use "brush alodine", where the chromate conversion coating is literally brushed on, allowed to dry, and then primer and top coat applied.  In our hobby, and with car resto's, the application of choice appears to be self-etching primer.  This stuff, I have found, is primer with a dash of acid.  The acid eats into the bare metallic surface a bit, and that provides the needed adhesion.  Then it acts as a normal primer for the top coat.  

 

So with my upcoming painting of the Corsair center wing and fuselage, and the engine cowling panels, I am concerned with good paint adhesion, and also potential for weathering.  At this point I think it will consist of light sanding, self-etch primer hopefully yellowish green, and the tricolor US Navy top coat.  I don't think a hairspray method will work well, correct me if I am wrong (at what point would I apply it?).  What I am also hesitant to do is to spray yellow ZC paint (either Chuck's MRP stuff or my Tamiya XF-4 watered down or whatever) over the self-etch.  Solely for the purpose of having it exposed during a weathering process.  I mean - how many coats of paint can you lay down before it's just too thick and the surface detail gets smoothed over?   

 

For weathering I don't have a plan yet.  It is here where I could use suggestions from those of you who do such a great job weathering your subjects.   It's a big deal - shore based Corsairs in the South Pacific were indeed heavily weathered.   

Edited August 9, 2022 by JayW

[Oldbaldguy]

A while ago, someone on here pointed out that real airplanes get dirty and “weather” from the top surface down.  When building plastic models, we often will wax artistic and will try to simulate weathering so that it looks real but often has little connection with reality because we start down deep in the finish and work our way out in layers until it looks “right”.  This probably won’t work in your case.  I’d think you would paint your model the same way the factory did so that you end up with a fresh assembly line paint job and then wear and weather your way down thru the layers until you get what you want, adding dirt and grime to the top surface as you need it.  That’s how it worked in the real world.   In places where your model has plastic rather than aluminum skin, you are just going to have to paint those parts aluminum or silver before you lay on any color coats if you want high wear areas to eventually show bare metal.  If you can teach yourself to metal-skin complex parts and all sorts of compound curves, then you can teach yourself to use an airbrush (they are marvelous devices) to get a realistic showroom finish.  Once you’ve down that, wrecking said paint job with wartime wear and tear is just another step on the learning curve - it’s all airflow, abrasion, handling wear, UV light, POL stains, dirt and common sense and all of it should happen to your model the same way it happened to the 1:1 Corsairs: a little bit at a time.  Start whenever you are ready.  I’m letting a bottle of Malbec breathe a little, so we have plenty of time.

[geedubelyer]

This is a fascinating topic Jay. 

I can see how paint adhesion on a full sized airframe would be important since the paint will be exposed to quite a harsh environment at times.

However, a static scale model is less likely to suffer from the ravages of external weather and sunlight so does the finish need to be as strong? 

If you take too much care the finish will be too strong and you might not be able to achieve the results you seek. 

Is there any mileage in creating a test panel? 

I think if I were tackling the task you've set yourself I'd perform the weathering in stages and possibly go a layer at a time. 

Lightly abrade the surface with some fine grit paper. Apply a coat of zinc chromate colour to the areas of heaviest wear, possibly using an enamel or lacquer type paint. The inner upper wing surfaces seem to be high traffic areas for example.

Rub through this once dry with fine grade abrasive until the base aluminium shows through. Patience and subtlety are key. It's a time consuming process but the more patient you are, the greater your rewards.

That stage should leave paint in recesses and around surface detail but also some flat areas of worn bare aluminium. This will all get sealed eventually after everything is done.

Apply hairspray and paint over with the top coat. It would probably be best to weather the actual colours at this point to fade them to represent sun bleaching.

The colour coat can be removed by moistening the surface and rubbing gently with a toothbrush or similar.  

Then possibly, repeat the abrasion step but go a little further this stage. That should leave primer showing through and bare metal too. If you can find an acrylic range with the colours you need so much the better for this stage. 

With that done final weathering could be done using powders to simulate dust over the airframe, oil paint for oil streaks and the airbrush again for exhaust stains or gun smoke residue. 

At least that's how I'd tackle it I think. 

 

HTH and good luck. I'm very eager to see how this turns out. 

 

Cheers

 

Edit* For the 3D printed areas like the cowl ring and wing intakes you could consider Tamiya's TS-30 "Silver Leaf" I think (or is it AS-12 "bare metal silver"?) rattle can. That stuff is as tough as old boots and could make a convincing looking substitute for real metal under all of this weathering.

 

Edited August 10, 2022 by geedubelyer

[JayW]

10 hours ago, geedubelyer said:

HTH and good luck. I'm very eager to see how this turns out. 

 

You sir have outlined a very plausible plan for painting this beast of a model.  Thank you for your input.

 

10 hours ago, geedubelyer said:

Is there any mileage in creating a test panel?

 

Oh yes.  Absolutely.  I even have a second 3D print nose cowl made before a mistake was discovered.  

[JayW]

I sure do have a calloused middle finger, and maybe the onset of carpal tunnel syndrome on my right hand, after creating THOUSANDS of little rivet and bolt marks on wing panels.  But huzzah - I am done skinning for quite a while!  Here is the fully skinned VS-10225 "Unit Assembly - Body Group - Fuselage Front Section & C. S."

 

 

 

Yes - once again I busted loose a landing gear door. 

 

A couple more shots:

 

  

 

 

I love how these fixed TE hinged doors came out (not hard to do):

 

 

 

There is now nothing standing in the way of painting this assembly, at least partly.  A giant milestone for me.  Some would wait until the aft fuselage was finished and joined.  I will have to wait until then to paint the two blue's, for sure, to avoid a mismatch at the join, and also to stencil the stars & bars insignias which span the joint.  The aft fuselage - LOL.  I haven't even started it!  Alot there.  Months worth.

 

At least I will prime it and apply the insignia white to the underside and fade it out along the sides.  Thanks to OBG, I found some self-etching primer that appears to be yellow ZC colored, if the color of the top is any indication.  It arrives next week sometime.  I already had some other self-etch that I bought locally, but it is dark olive green in color, and if I am to weather this thing like we all would like, I need to have a layer of yellow ZC, on top of the bare aluminum that can be exposed here and there, without any dark green showing up.  This stuff:  

 

 

Stay tuned for that.

 

As I wait, I will very likely go back to the engine and cowling assembly and start work on the cowl flaps and mechanisms.  Going to be micro-surgery.

 

And speaking of the aft fuselage, a sneak preview - I got some more 3D print parts in the mail from Tim Perry (tim@tjpgraphics.com):

 

 

 

The customary comparison shot with the toy part:

 

 

Big improvement.  A while back we all had a spirited discussion about tail wheel tires and wheels.  I ordered up both the fine tread and the coarse tread tires for print, and the Hayes wheels.  I thought I would be disappointed with the bulge detail on the fine-tread tire, and I am.  Modeler error - looks awful.  The bulge on the coarse tread tire is perfect.  So I will probably do a bit of putty work on the fine tread tire and see if I can improve the bulge.  If it works, I will use it.  If not, the coarse tread tire is a good back-up.

 

The tail wheel bay is going to be a hoot, I can tell ya.  But it's a little ways off.  Take care and I will update soon I hope.     

Edited August 10, 2022 by JayW

[Rockie Yarwood]

Beautiful!

[geedubelyer]

That beautiful surface detail is mouth watering and should create an uber realistic finish, totally in keeping with the rest of the build and well worth the effort. 

Great stuff 

[easixpedro]

Oh wow, that looks fantastic Jay!  I don't know what I'm more impressed with--that hook or the beautiful skinning job!? 

 

Glad you found the Duplicolor paint. Hopefully the YZC is a close enough match--I know the ZC sure is. That's the stuff I used to seal the bare metal after stripping my 67 Mustang.  Lot's of comments from my fellow aviators that I'd stolen paint from the corrosion control shop!  

[JayW]

2 hours ago, easixpedro said:

that hook....

 

You like huh?  Was a PITA to model in Rhino.  Yeah Peter - I can see how that feature has significance.  Still waiting to see if any of my followers complain about putting it on this subject....

[JayW]

4 hours ago, geedubelyer said:

That beautiful surface detail is mouth watering and should create an uber realistic finish,

 

Oh I hope so!  It added months to the build time although I must admit it was gratifying work.  More to come too - the aft fuselage and empennage are going to be bears.  Outer wings as well (they plus the ailerons, elevators, rudder will also see some sort of representation of fabric skins).  Primer comes soon - will give an indication of what the surface is going to look like, without all the mirror effects you see so far.   

[easixpedro]

1 hour ago, JayW said:

 

You like huh?  Was a PITA to model in Rhino.  Yeah Peter - I can see how that feature has significance.  Still waiting to see if any of my followers complain about putting it on this subject....

 

Guilty as charged. Most everyone I know has one stashed somewhere in their house.  Back in the old days, they were usually tossed over the side after a certain number of uses, so aviators tended to snag them. 

 

Don't recall if you reference this book in the 65+ pages, but's it's well worth your time: The Jolly Rogers: Blackburn, Tom, Hammel, Eric: 9780935553673: Amazon.com: Books

 

Tommy Blackburn was their first CO. Came up with the Jolly Roger insignia.  It's a great read, but I recall reading about that episode when I was a teenager and thinking it pretty significant.  With the benefit of the intervening years, it REALLY strikes me what an accomplishment that was!  And even cooler that you're replicating that snapshot in time!

[JayW]

2 hours ago, easixpedro said:

Don't recall if you reference this book in the 65+ pages, but's it's well worth your time: The Jolly Rogers: Blackburn, Tom, Hammel, Eric: 9780935553673: Amazon.com: Books

 

Yup - I got that book, just a couple weeks ago MOF.  Soon as I finish Hornfischer's "Last Stand of the Tin Can Sailors", i start on it.  Literally cannot put Hornfischer down.  Good god.

[easixpedro]

7 minutes ago, JayW said:

 

Yup - I got that book, just a couple weeks ago MOF.  Soon as I finish Hornfischer's "Last Stand of the Tin Can Sailors", i start on it.  Literally cannot put Hornfischer down.  Good god.

Yes!  You should try "Neptune's Inferno" after that. The USN losses at Guadalcanal are staggering. Industrialized warfare at its worst.  Sadly Hornfischer just past away from cancer a little over a year ago.