Candidate Support Pack - Scottish Qualifications Authority

Finishing heat sensitive fabrics
Introduction
Care in finishing must be taken with all fabrics because mishandling may cause
shrinkage, extension and/or distortion. The majority of fabrics will, however, behave
satisfactorily, but there are some where extra care is needed because they may be
affected by heat, moisture or a combination of both. The categories below list the main
fibre or fabric types and which caution is required.
Heat
The majority of man made fibres are thermoplastic and are therefore sensitive to heat.
Dry ironing above the temperature recommended on the care label will cause glazing
and possibly melting of the fabric. Scorching of natural fibres will also occur if the ironing
recommendations are not followed.
Polyvinyl chloride (PVC)
PVC is extremely heat sensitive and will soften and shrink at very low temperatures (ie
70 °C). Finishing is therefore not recommended. It should be noted that textiles containing
PVC fibres should not be accepted for either cleaning or washing.
Modacrylic
Modacrylics are usually used in fun furs and in flame retardant curtains and bedspreads
(Teklan). Shrinkage and deformation caused by heat will occur at temperatures as low as
60 °C. Fun furs should not be finished at all. They should be removed from the
laundry/dry-cleaning machine after an adequate cool-down procedure, and hung on a
hanger to stabilise.
Note — the garments should be removed immediately after the machine cage stops
rotating.
It is possible to finish modacrylic curtains by means of a vertical curtain finishing machine.
Moisture
Some fabrics are adversely affected by moisture.
Wool
Care must be taken with wool and all other animal fibres because instability can arise from
hygral expansion. Hygral expansion is the reversible change in dimensions that occurs
due to variable moisture regain of wool fabrics. So, for example, a garment that is steam
finished without pressure will tend to expand. If it is then air blown and cooled to room
temperature, it will tend to remain in the expanded state. On lightweight wool wovens this
GC8N 22 — Laundry Operations Level 2
7.19