Hi Kamil,
Here's an extract from my build log being written for my build of the W.29:
Wing rib tapes.
Reference:
Windsock Data File No.55 - Brandenburg W.29 by Peter M Grosz.
Fabric covered surfaces, particularly those on the wings and tailplane, were either applied from a continuous bolt of cloth or applied in sections.
Care was taken to match the separate fabric sections.
To strengthen the joins of fabric, ‘rib tapes’ of linen were stitched and/or glued over the rib joins.
These tapes could be either of the same colour or of a contrasting colour, including hexagonal and lozenge patterns.
Photographs of that period are generally of a poor quality and make it difficult to make out such things as rib tapes.
Rib tapes were either coloured blue (over the lighter coloured fabric) or pink (over the darker coloured fabric). Rib tapes were also cut from the same bolts of fabric.