Manufacturer: AviatticModern thinking favours the idea that tinted dopes were sometimes used on the undersurface of German airframes rather than "paint' giving a more translucent effect over the linen - this is our spin on the manufacturer Fokker's colour....their DR1 triplane in particular, surviving samples of which are quite distinctly pigmented (appearing towards turquoise only with age and linseed oil staining from varnish coats...)