Synthetic chemical fibre is one of the 49 fibres listed in the EU Textile Labelling Directive. The flakes of acetate are dissolved in acetone and filtered to obtain a white paste, ready for extrusion, with the possible addition of titanium dioxide for matting. This is a dry spinning process; there are no coagulation baths, the liquid threads extruded from the spinneret, are immersed in a hot air current that makes the acetone to evaporate, a process that solidifies the filaments.
It is also possible to create a variation in the final aspect of the filaments: they can be opaque, glossy or semi-opaque, depending on the % of titanium dioxide inserted; similarly, the section, generally jagged, can also be modified by varying the shape of the holes in the spinneret.
cross-section view
longitudinal view
Summarising as we did it in the previous edition for the cotton garments, we must expect the following behaviour for the acetate:
Colour fastness: the colour fastness to water and sweat treatments is low and there is no technical possibility to improve it for the following reason: acetate, although a regenerated cellulosic fibre (such as viscose, cuprous, lyocell, modal) is dyed in a completely different way and requires dispersed dyes for its dyeing. Since the dyeing temperature cannot exceed 85°C due to the thermo-plasticity of the fibre, the colour fastnesses to wet treatment (water washing, water and sweat) is extremely low. Triacetate can also be processed at higher temperatures, of up to 120°C, and therefore its colour fastness in wet conditions is better than the one of the acetates.
laboratory test to water washing and sweat
Colour discharges can occur especially in the case of the medium-dark colours, and therefore for the medium and dark solid-coloured garments, washing together with light-coloured garments should be avoided; while for the contrasting-coloured garments, water-washing should be avoided.
low colour fastness to water droplet
avoid damp ironing, this can cause surface changes
From all textile fibres, acetate is the one that has the lowest resistance to abrasion (see diagram below) and therefore generates failures and tearing, that are usually wrongly charged to the laundry.
RESISTANCE TO WEARING number of cycles to breakage in fabricto- fabric rubbing (Martindale Abrasion & Pilling Tester)
The crotch area of a polyester warp and weft acetate trouser.
After only few days of wearing, the acetate thread tears and breaks in the weft direction
Hem in 100% acetate lining that has torn from wearing
Low resistance to snagging (pulled threads and hair spillage) in continuous acetate yarns. Snagging (filament breakage) on 100% acetate continuous yarn garment
Instructions for care
For garments in contrasting colours, avoid water washing. Acetate loses some of its resistance when wet, however less than viscose; therefore, acetate garments must be treated gently when wet washing. Hand washing should be preferred; it is recommended to use a neutral soap for this operation; as the fibre has low resistance to wearing, it would be better to reduce the mechanical stirring and avoid wringing and rubbing the garments; they should be gently stirred in the soapy bath and pressed to remove excess water. Do not squeeze them when hand-washing, and do not spin them when using a delicate washing cycle in the washing machine, because they make fixed creases.
The garments are drying quickly, so they should be hung on special hangers to let the water evaporate while keeping them hanging freely and keeping their shape. It can be dry-cleaned, as it can be cleaned well also like this; you have to reduce the mechanical stirring (problems with abrasion and creases) and the temperature (otherwise it loses its brightness). Acetate is white coloured in its raw form, so normally it doesn’t need any bleaching, but if a bleaching treatment should be necessary, it can be used a diluted solution of hydrogen peroxide or sodium hypochlorite. Concentrated solutions of alkalis destroy acetate. Acetate is more resistant to acids than viscose, but is nevertheless decomposed by concentrated solutions of strong acids.
Condensation droplets might stain the acetate, that being a thermoplastic fibre, should be ironed at moderate temperature, even lower than required for ironing the viscose; if ironed at hot temperatures, the acetate tends to melt, favouring its adherence to the iron and stiffening the fabric once cooled. When dry ironing, its high thermoplasticity causes glossy and moiré pattern effects; so, it is necessary to reduce the iron pressure. Careful with the steam, as condensation droplets will cause stains, such as in the case of silk. It is well resistant to the action of sweat and seawater. It has a good resistance to the action of light, better than cotton and viscose. It is not resistant to mould and bacteria, and it is not attacked by insects (perfect for those fabrics that are daily exposed to moisture like shower curtains). The most appropriate care symbols are:
or (more safely)
di by ING. VITTORIO CIANCI
Direttore LART – Laboratorio Analisi e Ricerca Tessile
LART
Laboratorio Analisi e Ricerca Tessile
Textile Research and Analysis Laboratory
Via Vasco de Gama 2 41012 CARPI (MO)
Tel. 059 645279
lart@lartessile.it – www.lartessile.it
DETERGO Magazine # November 2023
