Armoured glass WW2 Fighters - Colour tint conundrum

[TorbenD]

To tint or not to tint?

 

I’m wondering if anyone can offer some thoughts on the colour of armoured/buttlet-proof glass used in WW2 aircraft. Specifically whether or not there is a natural aqua/green/turquoise tinge that comes from the overall thickness and type of glass lamination used.

 

NB All images below are for illustrative purposes and intended to be under fair use - I will remove any that that accidentally do not comply: 

 

There’s plenty online images of Modern Warplanes where this is quite prominent. I’m using Spitfires mainly to illustrate this here as there are plenty of examples restored and original but my query is also aimed at all allied and Axis aircraft where armoured glass is used.

 

 

But this colour tint seems either much diminished or non-existent on contemporary colour imagery. I believe the following are (hopefully) original colour images not re-coloured B/W

 

 

Another example pertinent to my current build - I believe the below Airacobras should have armoured glass inside the windscreen and in the frame behind the pilot’s head - no sign of tinting at all...  

 

 

Any guidance / further info or ref gratefully received... 

 

Cheers,

Torben

 

 

[Gazzas]

Torben,

     I cannot say that I have ever seen or read anything about tinted glass used in WWII aircraft in all of my years of studying the subject.

 

Gaz 

[LSP_K2]

14 minutes ago, Jennings Heilig said:

It wasn’t tinted, it’s just what you see with thick glass. Build what you see.

 

Agreed. I've seen both green and smoke versions.

[TorbenD]

Thanks guys - in case of any confusion, I agree it’s a natural tinge (not applied tint) to some kinds of thick/laminated glass  - just wondering why that colouring is strong on some and non-existent on others. Different type of glass? Perhaps more modern (toughened?) glass has more of this hue in it? Perhaps different thickness/lamination processes?

 

Torben

[D.B. Andrus]

Green, especially a very light one as found in glass, is one of the most difficult colors for color photographic film to capture accurately. In the commercial photo-separation process, it was always easier to work with a photograph that had an excess of green/yellow and remove that excess than to add green/yellow to the image. Not that strange to see "neutral" armor glass in period photos that have been through several photo and copy processes.

 

HTH

 

D.B.

[Tony T]

On jets, I've noticed the colouring from the outside but it often disappears looking out from the cockpit. 

 

Tony 

[LSP_Ray]

I think in part the green color is due to thickness of the glass, and refraction of the light. I am sure impurities in the glass magnifies this. I also think some glass will darken with age.

[GrahamF]

When i was in the army our APC's (432) had a little window in the rear door which had 7 panes of glass and that was very green, sodium based glass is the one that is not green. Notz do a series of thin tinted plexiglass and one of them is a dead ringer for green 'tinted' glass I have often thought if i was doing a spit in 1:24 i would use that for the front screen.

Graham

[dutik]

Same here with soviet style APCs. We had side windows/vision slits covered with bulletproof glass. 5-7 layers of thick glass sheets in a solid frame. The glass was never tinted, only thick clear glass, but showed a slight green tinting. Remember that armored glass is often a layer of uncoated glass sheets, so there is a good amount of refraction effects between each successive layer.

 

Regards

- dutik

[Thunderbolt]

Based on this, is it therefore appropriate to try to recreate a light green tinge in the armoured glass portions of ww2 fighter canopies? Was thinking of doing this for a spot IXc I’m finishing. 

[Landrotten Highlander]

3 hours ago, Thunderbolt said:

Based on this, is it therefore appropriate to try to recreate a light green tinge in the armoured glass portions of ww2 fighter canopies? Was thinking of doing this for a spot IXc I’m finishing. 

I think it comes down to 'artistic licence'.  combined with what you can achieve to make it look not OTT.

[Thunderbolt]

3 minutes ago, Landrotten Highlander said:

I think it comes down to 'artistic licence'.  combined with what you can achieve to make it look not OTT.

Thanks for the reply. This isn’t artistic license. There is a reality regarding how the armoured glass actually looked. Some posters online claim it was completely clear while others say there was a tinge. I understand most fighters today feature new glass from their post-war restoration that looks very green because a different mfg process was developed after the war. 
 

anyone?

[Landrotten Highlander]

I understand that you are referring to a real physical effect.  My note on 'artistic licence' is more related to what you want and can represent on your model.  Getting the tinting right without it looking artificial and 'unreal' is pretty difficult.

[AirCorps Library]

An example with a reference to the manufacturer's engineering data:

 

We are currently working on the canopy of our P-47D-23 restoration, and even with the protective film still on the glass, there is a slight greenish cast. The engineering drawing for this specific panel (Republic drawing 89F11808) notes that the glass panel is to be made out of Type I, Grade A laminated glass. The specification listed on this drawing with reference to the glass is: AN-DD-G-551. This spec is titled "Glass, Laminated", and details the manufacturer specs required by the Army/Navy in 21-Feb-1940 for this type of glass. This includes information on light transmission, light exposure, scatterability, and visibility distortion tests, among many other things. This spec also defines Type I, Grade A glass as "A laminated glass that is intended for use where perfectly undistorted vision is necessary to insure minimum error in navigation and other accurate observations."

 

We utilized this original spec, and the tolerances it provided, when we had these glass panels manufactured for our restoration, so presumably the green tint is normal when dealing with this thickness of glass. However, we are of course using modern materials, so there is a possibility that during WWII the tint may have been different.

 

Once the official pictures of this part of the project are posted, I will link to them if anyone is interested.

 

 

[Iain]

As others have said - a function of thickness and glass type/manufacture.

 

It's all in the eye of the builder model-wise IMHO - and I've used a blue/green mix of Tamiya clear colours reasonably successfully - at least to my eye.

 

A little overdone in photos - but looks good on the model, in normal lighting.

 

Example on the two-seat Spit I built a couple of years back:

 

 

 

 

Thinned with Tamiya thinners and applied by brush.

 

Iain