THE NATURE OF COTTON CORDAGE
Cotton cordage will attract dirt and, if left untreated, will not withstand weather or wear as well as a suitably finished piece. The right treatment depends on the intended use, the colour of the cordage and whether the finished work needs to remain flexible.
Before treating an important project, test the chosen finish on a spare piece of the same cordage. Finishes can alter the colour, texture, firmness and flexibility of cotton.
CUTTING HARD-LAID CORDAGE
Hard-laid cotton cordage can unravel very quickly when cut—sometimes with an impressive explosion of fibres.
Masking tape is essential. Wrap the cord firmly with tape where the cut will be made, then cut through the taped section with a sharp knife or, better still, a pair of flush cut pliers. Leave the tape in place until the end has been secured, hidden within the knot, whipped or otherwise finished.
Pre-treating cotton cordage with a weak solution of PVA wood glue or a mixture of potato starch—or possibly corn starch—can help reduce the immediate unravelling when it is cut. Test any treatment first, as it may affect the appearance or handling of the cordage.
SHELLAC
Dewaxed shellac is a traditional and effective treatment. The usual amber or brown shellac suits raw unbleached cotton, while blonde shellac is generally preferable for coloured cordage because it is less likely to alter the colour noticeably.
Shellac can also be combined with a small amount of Stockholm tar. This can give the cordage a beautiful appearance, additional protection and that familiar smell of the sea. It may also darken the work, so testing on an offcut is particularly important.
WATER-BASED POLYURETHANE
For a finished piece that does not need to flex, water-based polyurethane provides a simpler option. It will generally cause less discolouration than many solvent-based finishes.
Where the manufacturer’s instructions permit, it may be thinned slightly with water to help it penetrate the cordage. Several light applications are preferable to flooding the work with one heavy coat. Allow each coat to dry fully.
FLEXIBLE OR OUTDOOR WORK
If a finished piece needs to retain some flexibility or will be displayed outdoors, spar varnish may provide useful protection. It can alter or darken the colour of the cordage, so test it first.
No finish will make cotton cordage maintenance-free or permanently weatherproof. Outdoor work should be inspected periodically and recoated or brought under cover when necessary.
REMOVING EXCESS FINISH FROM SMALL ITEMS
For small items such as key fobs, I sometimes use what I call the “Bull Roarer” method to remove excess liquid finish.
After wiping or brushing off most of the excess, feed about one metre of strong twine through the eye of the fob. Hold both ends of the twine securely and spin the fob as quickly as you can. Centrifugal force throws off the remaining excess, helping to prevent a heavy surface build-up and leaving the finished piece feeling relatively natural once dry.
Make absolutely certain that you are holding both ends of the twine, or you may give your neighbours an unexpected gift. Do not stand with a window, wall—or the washing—either behind or in front of you unless you want to spend a great deal of time cleaning.
Only do this in a clear, well-ventilated area where the expelled finish cannot strike people, animals or anything that may be damaged. Make sure the fob and twine are secure, wear suitable eye protection, and keep flammable finishes well away from ignition sources.
CLEANING AND STORAGE
Dust can be removed gently with a soft brush. Avoid soaking or machine-washing finished knotwork unless you have already tested how the cordage and its finish will react.
If untreated cotton becomes wet, allow it to air-dry completely in a well-ventilated place. Avoid strong artificial heat, which may affect the fibres or distort the finished work.
Store unused cordage and completed pieces somewhere clean, dry and away from prolonged dampness or direct sunlight.
CHOOSING A FINISH
Knotters and ropeworkers have developed many other methods for treating cotton cordage. Ask a group of experienced knotters on social media and you may receive a myriad of answers.
The best treatment will always depend on the cordage, the project, its intended location and the required flexibility. If you are uncertain, experiment on a spare piece before committing an important project.
SAFETY
Follow the product manufacturer’s directions and safety information when using shellac, Stockholm tar, polyurethane, varnish, PVA or any other finish. Work with suitable ventilation, keep finishes away from children and ignition sources, and use appropriate protective equipment.
Mark Delaforce
Blood Knot