Fashion & Textile Technologies Basic Textiles VII Eline Oortwijn
MECHANICAL FINISHING
Many mechanical finishing processes require steam or moisture to lubricate the
fabric, but physical manipulation by mechanical action is the primary cause of
the change in fabric properties. hand, appearance, luster, thermal insulation,
dimensional stability, wrinkle resistance (synthetics).
Heat setting Thermoplastic synthetic fibers can be stabilized by heat.
Shrinkage resistance and wrinkle resistance. After dyeing.
Preparation for spandex or temperature sensitive dyes.
Napping Raises fibers to create fuzzy surface. Ex. Fleece.
Shearing Uses blade to remove fabric fuzz to create even surface.
Sueding Raises fibers on fabric using sandpaper-covered rolls. Leather
suede.
Calendaring For luster and smoothness by passing between pressurized
rollers, one faster than other. Polishes fabric.
Compacting Fabric shrinks in length by compression. Minimize shrinkage
during consumer use.
Relaxation Minimizes tension on knitted fabrics during drying. Fabric is
drying overfed into dryer for shrinkage in fabric instead of garment.
Decatizing For wool to improve luster and smoothness. Fabric is layered
between heavy cotton fabrics on roller and exposed to steam.
Flattens wool, improves hand and luster.
HEAT SETTING
Purpose: to impart stability to polyester and nylon fabrics by heating to 350-400
degrees F for 20-60 seconds.
For a fabric to be heat-set, it needs to have a Tg. Temperature above Tg,
polymer chains in amorphous regions become mobile and rearrange. Fabric will
retain memory and process imparts dimensional stability and wrinkle resistance
to synthetic fabrics.
Heat-setting after dyeing can dull or yellow the shade. Before dyeing, uneven
temperature exposure can lead to differential dye uptake (‘side-center-side’
shading). Differential shrinkage and width variation.
, Fashion & Textile Technologies Basic Textiles VII Eline Oortwijn
Tenter frame is used in open-width form. Selvages are clipped on chain. Clips
for wovens, pins for knits. Moves through heating zone (steam, natural gas,
propane or oil). Indicators: fabric temperature and dwell time.
NAPPING
Purpose: to lift or raise a layer of fibers from the surface yarns of a fabric to
form a raised surface pile to produce warmth and soft hand. Ex: fleece, flannel,
fake furs.
Napper contains wire-covered rollers that rotate against the fabric to pluck and
raise surface fibers. Indicators: machine type, speed fabric and rolls, condition
wires, fabric and yarn construction, fabric tension, presence of softener on fabric.
The yarns that come in contact with the napper should not be responsible for the
fabric strength as they will be weakened. Apply lubricating softener because
high friction.
Type of napping machine depends on fabric type and pile desired.
Single action nappers: rotating wire-covered rolls that
have wires angled in same direction long, one-
directional pile.
Double action nappers: contain rollers that alternate
direction of angle to produce non-directional pile.
Produces fleece. Large cylinder has 24, 30 or 36 worker
rolls. Large rotates in direction of fabric, small turns in
opposite direction. Cleaning rolls (fancies) underneath DOUBLE ACTION NAPPER
large cylinder to clean lint from wires.
Special nappers: for knitted fabrics to maintain width tension on fabric and
tuck pile back into base fabric to improve pile durability.
Issues and problems
- Overnap weakens fabric
- Wrinkles, creases and folds defects
- Napping goods of varying widths wide fabrics before narrow fbrics
because wires will not wear uniformly.
SHEARING
Purpose: to smooth a fabric surface by cutting raised
fibers to a uniform height. Napped fabrics are often
sheared to give an even pile height.
Ex. Fabric: terry loop ends in towels to produce smooth
and plush service. Can also cut pattern into pile fabric.
MECHANICAL FINISHING
Many mechanical finishing processes require steam or moisture to lubricate the
fabric, but physical manipulation by mechanical action is the primary cause of
the change in fabric properties. hand, appearance, luster, thermal insulation,
dimensional stability, wrinkle resistance (synthetics).
Heat setting Thermoplastic synthetic fibers can be stabilized by heat.
Shrinkage resistance and wrinkle resistance. After dyeing.
Preparation for spandex or temperature sensitive dyes.
Napping Raises fibers to create fuzzy surface. Ex. Fleece.
Shearing Uses blade to remove fabric fuzz to create even surface.
Sueding Raises fibers on fabric using sandpaper-covered rolls. Leather
suede.
Calendaring For luster and smoothness by passing between pressurized
rollers, one faster than other. Polishes fabric.
Compacting Fabric shrinks in length by compression. Minimize shrinkage
during consumer use.
Relaxation Minimizes tension on knitted fabrics during drying. Fabric is
drying overfed into dryer for shrinkage in fabric instead of garment.
Decatizing For wool to improve luster and smoothness. Fabric is layered
between heavy cotton fabrics on roller and exposed to steam.
Flattens wool, improves hand and luster.
HEAT SETTING
Purpose: to impart stability to polyester and nylon fabrics by heating to 350-400
degrees F for 20-60 seconds.
For a fabric to be heat-set, it needs to have a Tg. Temperature above Tg,
polymer chains in amorphous regions become mobile and rearrange. Fabric will
retain memory and process imparts dimensional stability and wrinkle resistance
to synthetic fabrics.
Heat-setting after dyeing can dull or yellow the shade. Before dyeing, uneven
temperature exposure can lead to differential dye uptake (‘side-center-side’
shading). Differential shrinkage and width variation.
, Fashion & Textile Technologies Basic Textiles VII Eline Oortwijn
Tenter frame is used in open-width form. Selvages are clipped on chain. Clips
for wovens, pins for knits. Moves through heating zone (steam, natural gas,
propane or oil). Indicators: fabric temperature and dwell time.
NAPPING
Purpose: to lift or raise a layer of fibers from the surface yarns of a fabric to
form a raised surface pile to produce warmth and soft hand. Ex: fleece, flannel,
fake furs.
Napper contains wire-covered rollers that rotate against the fabric to pluck and
raise surface fibers. Indicators: machine type, speed fabric and rolls, condition
wires, fabric and yarn construction, fabric tension, presence of softener on fabric.
The yarns that come in contact with the napper should not be responsible for the
fabric strength as they will be weakened. Apply lubricating softener because
high friction.
Type of napping machine depends on fabric type and pile desired.
Single action nappers: rotating wire-covered rolls that
have wires angled in same direction long, one-
directional pile.
Double action nappers: contain rollers that alternate
direction of angle to produce non-directional pile.
Produces fleece. Large cylinder has 24, 30 or 36 worker
rolls. Large rotates in direction of fabric, small turns in
opposite direction. Cleaning rolls (fancies) underneath DOUBLE ACTION NAPPER
large cylinder to clean lint from wires.
Special nappers: for knitted fabrics to maintain width tension on fabric and
tuck pile back into base fabric to improve pile durability.
Issues and problems
- Overnap weakens fabric
- Wrinkles, creases and folds defects
- Napping goods of varying widths wide fabrics before narrow fbrics
because wires will not wear uniformly.
SHEARING
Purpose: to smooth a fabric surface by cutting raised
fibers to a uniform height. Napped fabrics are often
sheared to give an even pile height.
Ex. Fabric: terry loop ends in towels to produce smooth
and plush service. Can also cut pattern into pile fabric.
