Varnish

[Maxim08]

I have been spending some time recently looking through early texts for primary sources on fabric covering practices.
One American text, published 1918, referred to a top coat of spar varnish on doped fabric to protect the dope. The text references this as a standard US Army practise.
Can anyone comment on this procedure and whether it was used by any other nation ie Great Britain, Germany or France?
Regards,
John

[Dan_San_Abbott]

Hi Maxim08:
The purpose of the top coat of varnish was to waterproof the surface. The problem with oil varnishes, they only provide a film over the doped surface, it does not merge into the dope. The normal doping pratice was three or four coats of dope. late into the war, dope became critical and the Germans in 1918 reduces the number of dope coats to three on the wings and tails and one or two on the fuselage.
Another detractor for oil varnish as a water-proofing coat is it take three or for days to dry, which is a deterent to production.
Merry Christmas Maxim08,
Dan-San

[Maxim08]

Dan-San,
Thank you for your thoughtful reply.
Frequently when I look at old samples of exposed ww1 vintage fabric, there is a distinct yellow tone to the finish. That was the reason for investigating top coating practise. When I look at samples of modern 'lozenge' fabric they are very bright and rich with colour. A coat of spar varnish gives a subdued and yellowish cast which makes the colours more earthen in tone and look much more like the 90 year old samples. I am debating whether to apply varnish as a top coat to my aircraft but not if there is no imperical basis for it.
BTW, I have always conjectured that lozenge was more of a disruptive camoflauge scheme than a 'you can't see me' based colour(s). It is amazing how easy it is to lose sight of a PC10 painted, full size aircraft, from only a thousand feet above when the target is viewed against foliage.
Merry Christmas to you and yours,
John

[gipsymoth236k]

My original Fokker D.VII top wing five color lozenge fabric shows a very yellowed varnish coating which is now flaking off from the clear doped surface.

Regards,
Gary Sewall

[Dan_San_Abbott]

Hi John:
I had not thought of the printed pattern as disruptive, I had thought of it as impressionistic, whereas the eye mixes the colors and forms the opinion of the object. The Impressionism School was in vogue the late 19th Century and early in the 20th Century with the works of Monet and others and their interest in the expression of color. The impressionism movement was fairly strong in Germany prior to the war.
However with the repetitive printed patterns, it does not look as disruptive as, say the black, grey and white abstract patterns like what what used on warships during both wars, which, I would deem as disruptive. However what you suggest, is an interesting idea.
Merry Christmas John,
Dan-San