This investigation was carried out at Faculty of Agriculture (Saba Basha), Alexandria University Egypt, in 2023 season.  To evaluate mechanical properties of cotton fibers and the resulting yarns as affected by variety, dying fibers before spinning and their interaction. It was conducted in a completely randomized design (CRD) with three replicates. The main results:

Super Giza 92 cotton variety recorded the highest averages for the yarn strength and elongation compared to the rest of the studied varieties.
The blended yarn (50% raw cotton fibers + 50% dyed cotton fibers) recorded the highest mean values for of yarn strength and elongation, while the lowest values were recorded by the yarn made of raw fibers dyed after the spinning stage.
 Cotton variety super Giza 86 recorded the highest mean values for the characteristics of the yarn irregularity (evenness CV %, the number of thin, thick places and neps), but the highest value for the hairiness characteristic was observed from the extra Giza 92 cotton variety, while the lowest thin and thick places and degree of hairiness were recorded from the super Giza 94, while the lowest number of neps was recorded from the extra Giza 92.
The highest values for the characteristics such as (evenness CV %, the number of thin, thick places, neps and degree of hairiness) were given from the yarn made from raw fibers dyed after the spinning stage. While, the lowest values of yarn evenness CV %, the number of thin, thick places, neps were verified from the raw yarn (without dying).