Air permeability is one of the fundamental textile properties influencing the design of comfortable clothes. In particular, it is very important in the field of technical textiles. Air permeability depends mainly on the fabric structure, which can be described by yarn linear density, type of yarn, warp/weft density and weave. The purpose of our study was to identify a small number of parameters that have the strongest influence on air permeability of cotton fabrics and enable its good prediction. Rather than focusing on the constructional parameters, we decided to include a composite parameter known from the theory of fluids, hydraulic diameter of pores, which treats rectangular-shaped pores as circular ones. In addition to the hydraulic diameter of pores, two other parameters were used for the prediction of air permeability: the number of macro pores and the total porosity of woven fabrics. 36 woven fabric samples were produced using nine frequently implemented weave types together with two warp densities (29.3 and 22 ends/cm) and two weft densities (15 and 20 picks/cm), resulting in four different densities of woven fabrics. The yarns had the same linear density and material in warp and weft directions. Air permeability measurements were performed with the Air Permeability tester FX 3300 Labotester III (Textest Instruments) according to the ISO 9237:1995 (E) standard. Principal components analysis revealed that the four investigated plain weave specimens behave differently than the other samples, which might be explained by weave structure. This multivariate statistical method also confirmed the appropriateness of the three selected parameters for air permeability prediction which was done using multiple linear regression. The high adjusted coefficient of determination (R2) value of 0.94 indicates that the model explains variability in the air permeability to a large extent.

In this paper, new approaches for evaluating the entire colour effect of optical mixing of bicolour woven structures are presented. Simple woven structures with constant colour in the warp direction and different colours in the weft direction were prepared and analysed. The constructional parameters of these woven fabrics were systematically changed, which resulted in the variations of the fractions of colour components and, consequently, also in the changes of colour properties (lightness, hue, chroma) of bicolour optical mixtures. The position of colours of the bicolour structures and the approximate direction (linear) of colour changes in CIELAB colour space were theoretically determined with a simple geometrical model and additive method. Furthermore, the bicolour optical effects were determined spectrophotometrically. The differences between the linear–theoretical and the spectrophotometrical colour values of bicolour woven fabrics were mathematically analysed with linear and non‐linear regression methods to determine the positions of colour coordinates L*, a* and b* of bicolour woven fabrics in the a*b* plane by increasing or reducing the cover factors of warp and weft threads (addition or reduction of colour components). The results present, on the one hand, the strong influence of original colours of warp and weft threads and, on the other hand, the minor influence of constructional parameters on the form of linear/non‐linear behaviour of colours of bicolour compositions. When the characteristics of a specific colour combination are taken into account, the spectrophotometrical colour values of bicolour woven fabrics can be also mathematically determined with additive–theoretical colour values and, to some extent, with predictable colour deviations.

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The research focuses on the influence of elastane (Spandex) incorporation in the weft direction of cotton fabrics, and the structural properties (fabric density, type of weave) on the thermal and water vapor resistance level. For that purpose, woven fabrics, in plain and twill weave with two different densities (17 and 20 yarns/cm) in the weft direction, were made from 100% cotton (conventional) and from a mixture cotton/elastane in the ratio 93.8%/6.2% (elastic fabric) intended for men’s shirts for the summer season. Thermal and water vapor resistance were determined with two novel methods, which were compared with the well-known Permetest method. The thermal resistance was calculated according to the thermal conductivity method which was established by the faculty research laboratory and with the Permetest, while the water vapor resistance was measured with the water cup method (developed by Professor D. Jaksic) and with the Permetest. The research results indicate that cotton fabrics in twill weave with elastane in the weft direction have higher thermal and water vapor resistance compared to conventional cotton fabrics. The reason lies in the higher yarn density of fabrics with elastane in the weft direction in twill weave (from 24 to 29–31 yarns/cm in the warp direction) compared to the plain weave (from 24 to 28 yarns/cm in the warp direction).

The importance of protection against ultraviolet radiation (UV) is increasing daily. The dependence of the UV protection level on different clothes is determined by the shape and design of fabrics, and especially by their construction parameters. The fabric structure represents an important factor which is in most cases the only condition for good protection. Other possibilities to ensure good or even excellent protection, mainly by finishing treatments, can be efficient only if the fabric structure is closed enough. To determine the key parameters which contribute to the closeness of the structure and offer suitable UV protection, an analysis of monofilament woven fabric structure was made. Monofilament fabric samples used in the production of high-module screen-printing meshes, which are characterized by the excellent dimension stability of the structure, the properties of which change with varying diameters of the monofilaments and the fabric density, were chosen for this research. A broad spectrum of similar but structurally different fabrics assures referential samples are available for the evaluation of UV protection properties. In all the samples tested, the parameters of transmission and reflection were measured. Moreover, the values of absorption and the ultraviolet protection factor (UPF) were calculated. The values calculated on the basis of a determined mathematical model matched well with the measured values and they can together represent the basis for successful planning of fabrics with suitable UV protection properties.