PRU Blue fading phenomenon

[DOD]

Hi All,

From my recent researches into Allied PR aircraft it appears that there is a recognised phenomenon of the PRU Blue paint fading a lot. I am fairly new to all this but it seems as if it fades more (or faster?) than other camouflage colours that I have seen in photos(?).

This post may seem a bit rambly as I put down some thoughts on the subject and ask for opinions!

A couple of examples.

1. F5E-2 Lightning Lanakila (a current project with faded paint)

 

2.Spitfire PR XI PL848

 

Is it known why it it seems to fade a lot?

Paint quality/Pigments

Weather

Sunlight

Combination?

 

Would the underside fade less than the top?

 

The PR XI shows the differences between faded paint and more freshly applied where the ‘Invasion stripes’ have been covered up. The rudder is also different and possibly the elevators. Replacements, touched up or does the fabric react differently to the metal? It would be interesting to see the rest of the aircraft.

 

In “The Mighty Eighth in Colour”, RA Freeman in addition to the above photo of Lanakila there is one of the aircraft as ‘new’ in fresh PRU Blue and Invasion stripes and you can see the difference in only a few months. 

 

The faded colour always seems quite patchy.

 

Now this seems a bit fanciful but the leading edges of the tail and elevators of the PR XI and the nose, leading wing edge and camera blister of the Lightning seem more like the original PRU blue. Is this due to repairs/touch ups or is there some effect due to these parts meeting the airflow first (yes I can hear you all laughing!).

I know to counteract this here is a photo of a couple of F5 Lightnings and it seems obvious that there have been several touch-ups performed.

 

Does anyone have other good examples of PRU blue fading, especially if there is a before and after shot to post. Any aircraft.

 

All thoughts and contributions welcome.

Cheers

David

[iainpeden]

I suspect the F-5 is Haze Blue which was part of a multi layer coating in an attempt to make the a/c invisible at height. It was notorious for fade. 

[Phoenix44]

I suspect the F-5s are haze as well. Is that shot of PL848 colorised though? The grass in particular looks odd but so does the pilot and the blues. My impression from b&w photos of PR Spitfires and Mosquitos that it stayed in pretty good condition, certainly for UK based aircraft. The colour photos that sometimes show problems seem to be more from Italy or mainland Europe where perhaps there was less time/ability to wash and care for aircraft? 

[Graham Boak]

All the wartime colours faded after a few months in the open air.  The sun is of course rather brighter higher up, where the air is thinner.

 

Yes, parts such as the leading edge were more prone to wear and so would be touched up as appropriate.

 

The base of Haze Blue was gloss black, and generally appeared very patchy.  Also this is rather late for Haze Blue still to be around - it was discontinued after discovering that it glowed at altitude - so I don't think that these examples are indeed in PRU Blue.  Or some US alternative not well recorded.

[Dave Swindell]

1 hour ago, DOD said:

2.Spitfire PR XI PL848

 

36 minutes ago, Phoenix44 said:

Is that shot of PL848 colorised though? The grass in particular looks odd but so does the pilot and the blues.

It does look rather like it's possibly colourised, if not the balance & contrast looks rather forced.

Assuming the tail is PRU Blue, it looks to me more like Medium Sea Grey has been used to paint out the invasion stripes

[DOD]

18 hours ago, iainpeden said:

I suspect the F-5 is Haze Blue which was part of a multi layer coating in an attempt to make the a/c invisible at height. It was notorious for fade. 

Hi, thanks for comment about possibility of Haze paint. However, the photo of the aircraft as new  mentioned in the original post is also reproduced in "Eyes of the Eighth, A story of the 7th PRG 1942-1945", P F KEEN where it states it is finished in PR Blue.

 

17 hours ago, Dave Swindell said:

 

It does look rather like it's possibly colourised, if not the balance & contrast looks rather forced.

Assuming the tail is PRU Blue, it looks to me more like Medium Sea Grey has been used to paint out the invasion stripes

The photo is from the Etienne du Plessis collection on flickr and I understood these photos were not colourised. (https://www.flickr.com/photos/8270787@N07/6178413915/in/album-72157605269786717/ ).

Spitfire in Blue, H Smallwood also reproduces it (ref RAF Museum). S/Ldr Tony Davis of 16 squadron indicating fresh paint on the invasion stripes. As it is a PR squadron I would presume they are using PR Blue rather than MSG.

 

[TAG]

Hey, fellas

 

Cabot Haze was an interesting scheme indeed, and very different from PRU blue. Here's what @Dana Bell has to say about it.

 

"Morning, All!

 

Here's a bit of clarification on the Haze Paints.  The original Cabot Haze was applied over a  totally black base coat.  The heavier applications of Haze to undersides resulted in a very light blue, while the lighter applications on top gave a much darker blue.  The vertical surfaces in between were graded from light applications down to dark.  Since accurate applications were nearly impossible to measure, there was a great deal of variation the the appearance of these aircraft, and as the slipstream and maintenance crews wore away layers of paint, the entire aircraft began to darken (particularly noticeable on leading edges).  The scheme was also very difficult to to retouch.

 

Two other paint companies provided their own versions of Haze.  Cabot took exception to the violation of his invention, but just as everything came to a legal head, the iridescence problem was discovered - at altitude the finish began to glow.

 

During F-5A production, Lockheed developed a two-color lacquer scheme that became known as Synthetic Haze Paint - a deep blue was applied overall, with a much lighter blue on undersides, in shadow areas, and graded up vertical surfaces.  In the color shots of 267332 above, you can see the countershading on the boom beneath the wing - a clear indication of Synthetic Haze.  Higher resolution copies of that photo also show the more subtle countershading on the vertical surfaces.  (Note that Xtracolor X160 probably needs a second color to make the scheme work - Synthetic Haze certainly wasn't monochromatic.)

 

As with the original Haze Paints, the lighter shade wore away with time - rubbed against by crews or the slipstream.

 

The AAF debated the value of Synthetic Haze, eventually eliminating it from the mod centers that built F-5Cs and Es.  However, the Director of Photography was convinced that the paint helped protect his crews, and it was often applied in the field.  Some units simply used a firm demarcation between the two blues - like a blue version of OD over Neutral Gray.  B&W and color photos can be hard to interpret - especially since many aircraft were instead painted with British paints.  If you can recognize two shades on your F-5E, you've got Synthetic Haze.  If you see only one shade, you're probably looking at one of the British colors.  (A number of decal sheets have been released with incorrectly identified schemes - the decals are still good, but you may want to re-evaluate your base scheme.) 

 

Best of luck with the model!

 

Cheers,

Dana"

 

From this thread:

Here's a couple of F-5 photos in the Haze scheme that illustrate well Dana's description:

 

Here's a period color photo of an F-5 in the later PRU blue scheme, as you can tell it is a single color (fading, stains, and blotches notwithstanding) and strikingly different from the Haze scheme.

 

And here's some bonus USAAF recce Spits in varying shades of PRU blue, all shot in glorious period color film.

 

Hope that helps!

 

Cheers,

- Thomaz

[DOD]

Hi Thomaz,

Many thanks for this.

I had seen Dana Bells article but the photos are new to me. I had not seen Ginger Snap either. Very interesting. I do have the Spitfire ones as I am doing PL914 in parallel with my Lightning F5E-2. The Spitfires do look tired!

All the best

David

[JWM]

I think the recce machines were flying mostly on high altitudes, and the UV radiation was more intense there then near ground. Likely this degraded the pigment, if it was an organic one.

Regards

J-W

 

[Antti_K]

Hello guys,

 

I have a book about Lightnings and there with colour photos. Some photos of this thread are also in the book. The book says that these Lightnings were painted with PRU Blue in England.

 

All photos show PRU Blue having a slight greenish shade. Then I have some American magazines from the 1980s with colour and B&W photos of Haze and Synthetic Haze paint. Haze looks more grey than PRU Blue and Synthetic Haze looks pure blue. There is a great variation between Haze painted Lightnings; some are very "pale" and some look very dark. The size of the pigment grain was carefully selected and the original idea was to create a colour that matched the sky around the plane. So thickness of the white paint layer greatly effected the blue "created".

 

Cheers,

Antti

[Jackson Duvalier]

10 hours ago, Antti_K said:

All photos show PRU Blue having a slight greenish shade. Then I have some American magazines from the 1980s with colour and B&W photos of Haze and Synthetic Haze paint. Haze looks more grey than PRU Blue and Synthetic Haze looks pure blue. There is a great variation between Haze painted Lightnings; some are very "pale" and some look very dark. The size of the pigment grain was carefully selected and the original idea was to create a colour that matched the sky around the plane. So thickness of the white paint layer greatly effected the blue "created".

 

Surely you've got a Tamiya mix to share?  🤭

[Graham Boak]

Yes, thanks to Antti I will change my comment to Synthetic Haze rather than PRU Blue.

[DOD]

12 hours ago, Antti_K said:

Hello guys,

 

I have a book about Lightnings and there with colour photos. Some photos of this thread are also in the book. The book says that these Lightnings were painted with PRU Blue in England.

 

Hi Antti, 

Thanks for your  comments. Can you tell me the title of the book?

Cheers 

[John B (Sc)]

Most interesting. Looking at that picture of PL848, there is another Spitfire in the background with what appears to be PRU blue rear fuselage and tail feathers plus D-Day stripes and some dark almost mottled camouflage over the forward fuselage.  Unless that is some sort of camouflage netting - any ideas? 

[Marvel Onkey]

Do the red dots on the fuselage above the wings of Spitfires PA 892 and MB 946 signify missions flown?

 

They surely can't be 'kills' on a recce bird can they? I was surprised to see 12 kills recorded on the nose of 'Ginger Snap', I'd always assumed all recce planes had the armament removed to reduce weight.

[DOD]

39 minutes ago, John B (Sc) said:

Most interesting. Looking at that picture of PL848, there is another Spitfire in the background with what appears to be PRU blue rear fuselage and tail feathers plus D-Day stripes and some dark almost mottled camouflage over the forward fuselage.  Unless that is some sort of camouflage netting - any ideas? 

Hi John,

I believe it is a protective cover over the front of the aircraft. I think the aircraft were left out in the elements at Mount Farm airfield.

David

[DOD]

40 minutes ago, Marvel Onkey said:

Do the red dots on the fuselage above the wings of Spitfires PA 892 and MB 946 signify missions flown?

 

They surely can't be 'kills' on a recce bird can they? I was surprised to see 12 kills recorded on the nose of 'Ginger Snap', I'd always assumed all recce planes had the armament removed to reduce weight.

Yes, it records missions flown. You can see the little swastikas on the Lanakila photo as well.

Cheers

David

[Marvel Onkey]

1 hour ago, DOD said:

Yes, it records missions flown. You can see the little swastikas on the Lanakila photo as well.

Cheers

David

Thank you, that makes sense. 

 

It has just occurred to me that kills belong to the pilot not the airframe, so Ginger Snap and Lanakila could be displaying kills the pilot made prior to flying recce missions I suppose.

[John B (Sc)]

1 hour ago, DOD said:

Hi John,

I believe it is a protective cover over the front of the aircraft. I think the aircraft were left out in the elements at Mount Farm airfield.

David

Thanks David, that makes sense. It appears to be a good close fit over the forward fuselage.

[Antti_K]

Hello guys,

 

here are the books and magazines I was talking about. I have a couple more but can't find them just now. I created some pictures showing Haze, Synthetic Haze and PRU Blue paint schemes. Note that both "Haze" and "Synthetic Haze" were paint schemes consisting of two paints.

 

 

 

 

 

 

 

 

 

Probably not answering the OP's question exactly, but hopefully useful for all reconnaissance Lightning modellers.

 

Cheers,

Antti

[Antti_K]

Here is a confusing one:

 

 

The caption says this F-5 was painted with PRU Blue that has since heavily weathered. To my eye the colour is too uniform especially on the sides and under surfaces to be faded PRU Blue. I think this Lightning was painted with "Flight Blue" overall.

 

Cheers,

Antti

[Aidrian]

Blues were often problematic, especially when they used an ultramarine pigment, as the blue tends to bleach when mixed with zinc oxide white, which was the usual white used in this period. (Yes titanium white was well known back then, but most of it came from Norway, which made it a bit difficult to get hold of in large quantities). Prussian blue also fades in the presence of some other compounds, though the effect is slower and less startling. So, if the paint used for PRU had a significant amount of ultramarine in the mix and if the grey component contained zinc oxide, as seem almost certain, it would be likely to fade quickly. 

 

Heaing off on a tangent, this may be why the post-war roundel blue changed; the earlier version is very slightly warmer and suggests an ultramarine pigment but the 1964 version of BS381C has a new number (110) for Roundel Blue; from memory (not keen on spending an hour hunting through the shelves for what I need ) the old 1948 version (108) is called Aircraft Blue. The later colour is a very slightly cooler shade, which suggests pthalo blue, which is far more stable.

[DOD]

On 17/01/2022 at 12:32, Marvel Onkey said:

Thank you, that makes sense. 

 

It has just occurred to me that kills belong to the pilot not the airframe, so Ginger Snap and Lanakila could be displaying kills the pilot made prior to flying recce missions I suppose.

Hi, belated update. The aircraft were generally pooled and flown by a variety of pilots so the swastikas would refer to missions flown by the aircraft. 

[DOD]

23 hours ago, Antti_K said:

Here is a confusing one:

 

The caption says this F-5 was painted with PRU Blue that has since heavily weathered. To my eye the colour is too uniform especially on the sides and under surfaces to be faded PRU Blue. I think this Lightning was painted with "Flight Blue" overall.

 

Hi Antti 

I do have that Lightning  book.

From the serial number (42 68273) the F5 is a F5B-1.

I feel there is a slight darkening on the bottom(?).

In Air Force Colors, vol 2 by Dana Bell under the Synthetic Haze Paint section he states " Photos show a one- color scheme for F5E in England,  probably using PRU Blue or Azure Blue."

Is it possibly Azure blue?

Interestingly, though, looking through the Sortie list for 1944 of the 7th PRG there is no mention of this aircraft, though there are some gaps. (Eyes of the Eighth,  PF KEEN)

Cheers

David

[Antti_K]

Hello David,

 

I thought that the slightly darker blue is just an optical trick caused by the curvature of the nose (or booms). Sun light reflects from the surface at different angle on those areas having greater curvature and thus creates a "different" blue.

Doesn't Azure Blue have a purple hue? Something like that is visible on the lower nose. I concentrated on the sides of the nose and compared the picture with the photo showing Synthetic Haze and concluded that the colour in this photo could be Flight Blue. But now I'm not so sure anymore. You certainly made an interesting suggestion🙂

 

Cheers,

Antti