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9 Abstract 10 Detailed information on web geometry and the material properties of the various silks 11 used elucidates the function of the web’s different structures. In this study we investigated the 12 non-sticky spiral in Nephila edulis webs, which in this species is not removed during web13 building. This permanent non-sticky spiral shows several modifications compared to other, 14 i.e. temporary non-sticky spirals; it is zigzag shaped and wrapped around the radial thread at 15 the elongated junctions. Material properties of silk in the non-sticky spiral and other 16 scaffolding structures (i.e. radii, frame and anchor threads) were comparable. However, the 17 fibre diameters differed with the non-sticky spiral threads being significantly smaller. We 18 used the measured data in a finite element (FE) model of the non-sticky spiral in a segment of 19 the web. The FE analysis suggested that the observed Zigzag index resulted from the 20 application of very high pre-stresses to the outer turns of the non-sticky spiral. However, final 21 pre-stresses in the non-sticky spiral after reorganisation were down to 300 MPa or 1.5-2 times 22 the stress in the radii, which is probably closer to the stress applied by the spider during web23 building. 24