Study of Dyeing Process of Hemp/Cotton Fabrics by Using Natural Dyes Obtained from Rubia tinctorum L. and Calendula officialis

Abstract

The objective of this work was to assess the possibility of dyeing a substrate composed of non-textile industrial hemp using natural dyes from common madder (Rubia Tinctorum L.) and calendula (Calendula Officialis) and tannin and alum as mordants. The substrate used for the dyeing had a 25/75 hemp/cotton composition. The hemp raw material is an agricultural by-product that was subjected to mechanical and chemical treatments in order to cottonize the fibers, blend them with cotton, and thus obtain first 40-tex open-end yarns and then a knitted fabric. The latter was subjected to different dyeing conditions by varying the dye, mordant, and method for its application, type of water, and rinsing after dyeing. Measurements of the difference (ΔE) and intensity (K/S) of color and fastness to washing and rubbing were carried out. The results showed that dyeing of a non-textile residual hemp substrate is possible, and that calendula is a good option for dyeing it with tap water, tannin-alum set in a meta-mordanting process, and rinsing after 24 h. In this way, a contribution has been made to the circular economy of the textile industry through the use of more sustainable sources and products.

An Observation on Dyeing Techniques of Polyester/Cotton Blended Fabrics Using Various Dyes

“…As a result, it is possible to acquire comparable or superior characteristics by blending cotton with other natural fibers, such as hemp. Also, because natural dyes don't naturally have an affinity for cellulose, a mordanting process is required to securely bond them to the threads of textiles [16].…”

“…The hemp fibers were opened, cleaned with a non-ionic surfactant, dried, and then subjected to an alkaline bath, mostly containing NaOH (10 g/L), followed by an oxidizing treatment, primarily containing H 2 O 2 (50% w/v) 1 g/L. Hemp was cooled after the treatments, washed, neutralized with acetic acid at a concentration of 0.6 g/L, rinsed with distilled water, and dried at room temperature [16].…”

“…A hemp/cotton 25/75 blend was determined. After obtaining the knitted materials, various procedures were conducted to determine the most appropriate dying circumstances for the chosen cloth [16]. The following are these procedures:…”

“…[15]. And other natural dyes like Calendula officials and Rubia tinctorum L. were included as colorants for cotton blended fabrics [16].…”

Comparative Assessment of the Dyeing Process for Pristine and Modified Cotton Fabrics towards the Reduction of the Environmental Fingerprint

“…The textile industry consists of several process steps including the conversion of fibers into yarns and yarns to fabrics. Finishing of the fabrics is achieved through a variety of manufacturing and dyeing operations of either yarns or fabrics [3,4]. Dyeing is the application of dyes to textile materials such as fibers, yarns and fabrics with the goal of achieving the desired color fastness.…”