Decals, for helmets, ceramics, etc

[Les]

I picked up a 1930's era book titled "Fortunes in Formulas, 10,000 trade secrets, recipes and processes for home, farm and workshop" edited by Gardner Hiscox. There are thousands of methods for making what was then state of the art items such as paints, cleaning solutions, photographic solutions, and so on. Most of these items are now obsolete ways of making things.

One of the interesting processes described in detail is how decals (called "decalomania") were made, first by preparing a paper with specific requirements, using a three step process of overlaid chemical compounds, then the creation of the image to be transferred, and finally, how to do the transfer itself using another set of either water, or other chemicals.

The point in mentioning there was an older method of making and using decals, is how different modern decals are, compared to what was used during the WWII era, and in some cases continued on through the late 1950's and early 1960's. For those of us who are old farts, remember how -THICK- decals used on model kits from that era are?

Part of the explanation for the thickness is not that the images were fragile, but the application of several layers of chemicals designed to allow the separation of the paper from the image, was related to the thickness of the image being transferred. The image could be a photo printed on a clear substrate using photographic methods, or by the printing press method.

German decals of the national eagle are different from standard decals in the use of aluminium powder that is part of the chemical solution (technically called an "emulsion" which require a layered binder that allows the metallic based image to be transferred intact. This is very different from modern decals which are often something along the lines of a thin plastic like material that will break down if left to soak in water too long. Older decals often required the kerosene or something similar so the decal layered compound would separate from the paper.

The section on "decalomania" doesn't discuss transferring decals onto metal, however, it does go into a lengthy (500 words or so) using ceramics as an example. One thing that both metal and ceramics have in common after a decal has been applied, is the application of a protective layer on top. With ceramics, the protective layer can be fired at low temperatures to bind and seal the layer so it isn't affected by water, limited chemical exposure, etc. The section and all of the related topics are far too long to include verbatim here.

Since German helmets were painted, then baked to harden the applied factory finish, a protective layer to the decal could be added before the helmet shell was fired, and one step rather than two used. Not only that, firing paint creates a hard and often smooth surface that doesn't necessarily allow the best adhesion for a decal. Paint when applied can be pourous, and consequently, rough enough to allow decals to adhere. It would make a great deal of sense to paint the shell, apply the decal and protective finish, then fire everything, sealing the decal, and hardening the paint finish. That's not how reproduction or modern fakes are made....

Another thing about paints used before 1970, is the use of lead which was important in providing a binder that aided in blending the paint and preventing separation of the paint compounds, permitted better adhesion to metal surfaces similar to a primer, and a surface smoothing agent. The lack of lead in almost all pre-1945 paints, is something to watch out for.

All in all, the book is very useful in discussing period compounds, methods of making things, etc, and comparing the same to the the present. It is a useful reference source on period methods, and as such, a tool that can be used to determine fakes versus the real thing.

 

[Stuka f]

Have to pick up a copy!

Had a similar experience with a book that was much older. Every time I tought having found a new technic to do this or that, found out it was all ready used more then 200 years ago.

I'll post more info about the book,as soon as possible.

[Les]

I did some checking and found it on-line. It can be viewed here:

http://catalog.hathitrust.org/Record/006165736

Registration and use is free to everyone.

I haven't tried downloading since I have a hard-bound copy.

[Hoss]

Thanks Gents

Les I hope you had a good time at the gig, I did in part but I'm getting old,,,finally.

Cheers

[Jock Auld]

very interesting!

Cheers

[Hoss]

Les

The waf dudes are rattling on about those SS non decals that apart from dealers nobody really favoured imo. I thought you'd be interested, I can't see the darn pics of course or Val link,,,was wondering how they may react to a UV light?

http://www.wehrmacht-awards.com/forums/showthread.php?t=834155

Also do you recall an excellent SS and party decal that came out around 1980? They were very good fixed with clear lacquer but three points: a. they were very 'thin' b. failed UV and c. the party decal red field was the wrong 'shade'. I was one person that got done buying one. This was of course pre more modern fakes.

Actually I wish I still had that helmet to show people, there is no doubt in my mind they still catch out the unwary.

Eric

[Les]

Eric,

Thanks for the heads-up on the thread. I read through it, and followed the link to the helmet site where the "decal" is discussed in detail with extremely good photos. The helmet site thread is straight-forward and isn't all that difficult to follow through to the obvious conclusion. Apparently a single individual has been responsible for making a painted on "decal" over many years. I'm surprised it took years for the item to get de-bunked.

The helmet site article gets the use of XRF off of center, claiming it can't be used for authentication. It was never intended for that purpose. XRF can tell you materials composition within limits, and in the case of a decal or paint is capable of picking up paint composition under the decal, and then giving a reading that combines both. There's no problem with using XRF technology, as long as the person getting the results is aware of testing issues, and understands how to properly interpret the results.

XRF applied to any material produced over more than one or two years, and in different batches can and will not usually be identical from batch to batch, because mixing materials and paints is not as much a science as it is making due with what's on hand and wartime shortages manufacturers having to make do with less than what "spec" calls for.