Avoiding the felting trap

24 February 2021



In a new series of What Went Wrong, experts Roger Cawood and Richard Neale detect and find solutions for common problems cleaners run into. In the first of these targeted masterclasses, the expert duo tackles felting


Luxurious fabrics made from natural animal hair fibres need some basic expertise and craft skill from the cleaner in order to satisfy the customer. Felting is the term given to the serious matting caused by incorrect control of moisture in the garment or in the cleaning system. It is generally accompanied by excessive localised or overall shrinkage, thickening of the fabric, loss of drape and an audible crackling when the fabric is placed under tension. It is usually totally avoidable and preventing it is part of the cleaner’s craft skill. Unfortunately, felting cannot be rectified, but we describe in this article how you can avoid it.

Where does moisture come from?

The following table gives just some of the many sources of moisture in drycleaning. Minimising the amount of moisture still in animal hair items when they go into the drycleaning machine will substantially reduce the risk of felting and customer disappointment, with immediate effect.

Moisture regain in cleaning unit

Water vapour is an important constituent of the air we breathe. The warmer the air, the greater the percentage of water vapour it is capable of carrying. In a busy cleaning unit, the air can be very warm and well able to retain a considerable weight of moisture, especially in units which make use of a free-steam press. This moisture is particularly attracted to expensive animal hair fibres, such as wool, cashmere and angora, so that a good quality lambswool coat weighing, say, 2kg when bone dry could carry a further 500ml of moisture in a warm, very humid unit! The garment will not even feel damp! This can be bad news for the cleaner, as the moisture causes the scales on the wool fibres to rise and any movement is likely to create the ‘ratchet and lock’ effect described in the diagram.

This is not a big problem in wet-cleaning, because the cleaner has to minimise the mechanical action in the cleaning process for hair fibre items, by limiting the number of rotations per cage minute, reducing the cleaning time, increasing the dip and using special detergent systems which limit interactions between the scales.

Drycleaners have much more to do: ideally, they must ensure that items are thoroughly conditioned in a warm and relatively dry place (such as in the boiler room), preferably overnight (because airing out takes time).

Expensive hair fibres should ideally be cleaned after the ‘Good morning!’ programme, or as the second load of the day in order to avoid the risk posed by overnight condensation in the drycleaning machine. These two simple procedures will remove over 90% of the risks associated with unwanted, ‘invisible’ moisture in garments going into the drycleaning machine, reducing instances of greying and shrinkage quite considerably.

Overall felting is normally accompanied by shrinkage

Item: This cashmere skirt looked beautiful on receipt, with little wear and no stains. It was labelled for delicate cleaning with P in a circle with bar beneath.

Process: It was cleaned in perchloroethylene on a delicate cycle.

Problem: On removal from the machine, the material was thick and stiffer, with shrinkage to the outer, which revealed considerable excess of lining material hanging down below the hem. When the material was stretched by hand, an audible crackling could be heard, but the material did not have enough elasticity to allow much recovery in pressing.

Cause: This garment displays classic symptoms of felting shrinkage. It has been put into the machine without being thoroughly conditioned and the amount of moisture it was carrying has then caused the scales on the wool and cashmere fibres to rise (see diagram given earlier), so that they have ratcheted and locked with every movement in the cage.

Responsibility: It is generally held to be the cleaner’s responsibility to ensure that hair fibre garments, such as this one, are thoroughly dried to remove any excessive moisture regain before drycleaning.

Rectification: Unfortunately, none is possible.

Localised felting causes wrinkling and patchiness

Item: This wool throw came in with some minor staining which the owner identified as coffee with cream.

Process: The cleaner treated the marking with a protein remover to take out the cream, giving it time to soften this before flushing to remove it. A tannin remover was then applied to decolour the coffee colouring, which (with the cream protein out of the way) was very rapid. The tannin remover was then flushed out. It was drycleaned in perchloroethylene on a delicate cycle.

Problem: On removal from the machine, the treated area appeared matted and felted and it had shrunk significantly.

Cause: The symptoms described are consistent with the cleaner not having dried the treated area sufficiently before it went into the cleaning machine. The scales on the still-moist fibres have risen, and interlocking has occurred with the mechanical action of the process. Even a delicate cycle will cause this if the fabric is not bone dry.

Responsibility: It is generally held to be the cleaner’s responsibility to ensure that areas on a hair fibre item which have been pre-treated with water-based spotters are thoroughly dried before drycleaning.

Rectification: Unfortunately, none is possible.

Masking

Fine, high-quality hair fibres face a very high risk from wet side spotting kits and from general pre-spotting soaps that have been mixed with water. Damage can present as locally raised surface fibres or slightly darker areas, which can look like a faint stain. Liberal and excessive use of 50/50 soap-water solutions can easily lead to excess moisture in the machine resulting in overall felting of several items. Ideally, the cleaner should ensure that water-based pre-spotting chemicals are flushed out and the area thoroughly dried off before drycleaning.

Although robust fabrics can be ‘masked’ by brushing the area with an appropriate pre-spot detergent applied neat, this may not apply to fine, soft, high quality hair fibre items. These need to be bone dry when they are put into the drycleaning machine.

If you have problems you would like the authors to examine please send with a good quality, high resolution (300dpi/1MB at least) pic of the item to [email protected]


Main sources of unwanted moisture on an item in a drycleaning machine:

  • from a spillage in use
  • from condensation in the home or car
  • from rain or snow or fog acquired in Transit
  • from humidity in the cleaning premises
  • from pre-spotting with water-based Spotters
  • from ‘slop spotting’ with soap-water Solutions
  • from overnight condensation in the cleaning machine itself
  • from a machine fault:
    • leaking condenser coil resulting in water contaminating the distilled solvent
    • dirty water separator allowing carryover into the separated solvent.

About the authors

Roger Cawood

has, since1963 been amassing an encyclopaedic knowledge of drycleaning and has trained many of the UK’s current drycleaners. Best practice is his mantra

Richard Neale

is an expert in drycleaning and laundry technology, founder of the Drycleaning Technology Centre (DTC) and the Laundry Technology Centre(LTC)

Tip of the month

Correcting localised surface faults on the cleaned garment

Localised surface faults caused by wet side pre-spotters and/or vigorous use of the spatula can often be corrected by careful shaving with a safety razor, followed by firm finishing with a steam iron in conjunction with vacuum. Even localised surface felting (which sometimes looks like a faint stain) can be improved with care, provided there is no significant wrinkling or localised shrinkage.

DEEPLY FELT: Animal hair fibres (such as wool or cashmere) have scales, which open up in the presence of moisture to give the fibre a serrated appearance. When they move against a fibre the other way around (as in the lower two fibres in the schematic diagram above) they may ‘ratchet’ and ‘lock’, and cannot pull apart, leading to felting shrinkage


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