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Select a topic below to see related Frequently Asked Questions. If you don’t find the answers you're looking for, use our Contact Us form to e-mail your information request to the appropriate Coats contact.
Coats does not recommend adding any additional lubricant/silicone to thread. It can change thread color and cause variations in friction, resulting in oil stains. Atomized silicone may also pose a health issue if inhaled by operators/machinists.
Coats does not recommend thread rewinding since this can have detrimental effect on thread itself. The lubricant on thread will be lost during the process. The rewinding will add extra twist on thread causing snarling/lively. Rewinding may also cause damage to bonding on bonded threads.
Coats offers a full package service called Coats Sewing Solutions / CSS where Coats technical personnel can be involved from development to final stages of production.
Check thread-needle size compatibility and needle condition. Check components in contact with thread (thread path, tension discs, needle eye, bobbin, rotary hook) and also machine timing.
Check working condition and parts of sewing machines (i.e. hook, bobbin case, throat plate, needle tip, sharp thread guide) plus thread quality and material thickness.
We recommend the use of Super Lubricated products in conjunction with titanium nitride needle to minimise needle overheat.
To improve seam elongation, you can increase the stitch rating per cm or inch, increase the bite, reduce the needle/looper tensions on affected seams, or change the type of thread used.
If the needle cuts are always on the top or bottom fabric ply, then most likely the problem is NOT needle cutting but some other part of the machine that is damaging the fabric. Checking machine surfaces is important in such cases.
More details are available on our website. Please navigate to Solutions/On-line Training/Common Sewing Problems and Solution/Chapter 2 - Needle Point Style.
Stitch type, seam type, thread type and size etc. play vital roles in seam strength. Choosing all these properly can enhance seam strength.
A generic formula is available to determine seam strength:
For lockstitch = Stitch per inch (SPI) x Thread breaking strength (STS) x 1.5
For chainstitch = Stitch per inch (SPI) x Thread breaking strength (STS) x 1.7
Most broken stitches are the result of not using the correct thread type and size for the process it has to go through changing the stitch rating, stitch balance and setting machine thread tensions correctly will help to reduce issues as will thicker or stronger thread types. Use Coats corespun threads to provide better abrasion resistance. Also consider using a looser stitch so the stitch rolls rather than pops or cracks during contact with stones or enzyme.
This is the transfer of colour from materials into threads which have been sewn into the seam. The result is an unsightly seam appearance and can be caused by poor tanning of the leather, poor fastness of dye-stuff materials, solvent or adhesive reacting with dye chemicals, excessive needle heat, fibre migration is the break down of material fibre which attaches to the threads causing contamination.
Staggered stitches have a negative impact on seam appearance as deviation from the stitching line leads to a perception of poor quality. The needle is vibrating or deflecting.
Coats does not recommend adding any additional lubricant/silicone to thread. It can change thread color and cause variations in friction, resulting in oil stains. Atomized silicone may also pose a health issue if inhaled by operators/machinists.
There are spiral / coil zips, plastic moulded and metal zips. See the Product Information on our website.
Sewn Coil Zips are made from sewing a coil of monofilament, normally polyester wrapped around a polyester cord , onto 2 tapes , normally also made of polyester. See the Product Information on our website.
Previously these zips may have been made from a range of manmade materials like nylon, polyester, polypropylene, poly butyl phthalate (PBT). Nylon was a common material used for zips due to its smoother feel and so this remained as a name for this category of zips.
Spiral zips are made from integrally weaving monofilament into the centre of the zip as one continuous process. Because this process only involves two materials this is a more quality efficient process. See the Product Information on our website.
Plastic moulded zips are normally made from Polyester Tapes and Poly Oxy Methylene (POM) teeth. Alternative materials can be used for teeth such as Polypropylene for clear teeth materials. Other more highly technical plastic materials can be used for more specialist end use. Zip tape is generally polyester.
Metal zips are normally made from Polyester Tape and Brass Teeth. Other materials can be used for the tape such as Cotton, a mix of Poly/Cotton. See "Choosing the right zip" Garment Dye. The teeth can also be made from Aluminum to reduce weight and Steel / Copper for some specialist industrial applications.
Metal zips are made by attaching the teeth to the beaded edge of the tape. The teeth can be made from flat brass wire or shaped wire and attached directly to the tape. Or the teeth can be stamped first and then polished / plated before attaching making a very high quality zip. Usually, these are for high end bags / garments where very smooth teeth are required. In some cases the teeth can be die cast directly onto to the tape, but this process is now very seldom used due to advances in the other technologies.
Closed end zips (i.e. pockets/skirts/trouser), open end zips (i.e. centre front of jackets), two way zips (allow the zip to be opened from the bottom and also fully separated (i.e. long coats), X type zips (two sliders facing away from each other, i.e. large art folders that can be accessed from right or left side), O type zips (two sliders facing one another, i.e. generally used in bags/suitcases). For more information see the Product Information.
At the top of the zip there are the Top Stops that stop the Slider (moving part) from detaching from the zip. At the bottom of a closed end zip (pocket/skirt zip) there is a Bottom Stop that prevents the bottom of the zip from opening. On an Open End Zip (Seperating Zip as used in the Centre front of a jacket) the bottom components are generally referred to a Free Pin and Box Pin. The box pin being the larger female part of the two components that allows the free pin to be inserted to close the zip. For detailed informaiton of Top Stops, Bottom Stops, Slider and Pullers see Product Information on our website.
The top end stops on metal zips are normally made from brass wire. This is also the case for Spiral zips when metal stops are used. Aluminum wire stops are sometimes used. Polyester filaments can also be used to form top and bottom stops on spiral zips, as can Poly Oxy Methylene(POM) which is also generally used on Plastic Moulded zips. Some spiral zips can also have Brass Pin Bottom Stops, these are especially suited for footwear due to their high strength. Some Spiral/Sewn Coil zips have simple welded bottom stops sealing together the teeth. These are not usually very strong and normally stitched into the seam. Details can be found in the Product Data Sheets. See Opti Website for Product Data Sheets.
The slider are generally made from a Zinc Alloy, thought working components inside the slider maybe made from Steel or Brass? Plastic sliders are also available, though these are not as strong. Sliders made of stamped brass are also used generally for jeans applications.
The pullers can also be made from zinc alloy and a variety of materials such as Polyurathane, Wood, Silicone, PVC, Fabric, Textile Tapes, Brass - the material is usually requested by the designer though advice must be sought when using materials unusual for the application.
There are many ways to measure the length of a zip, Coats Opti follow the British Standard Method, where all measurements are based on measuring from the end of the components or head of the slider where fitted. More clear details and images can be found in the Product Information on our website.
The top and bottom tape end extensions (see Zip Component Descriptions) can be important for positioning the zip in the application. This may vary from one zip company to another so it is important to check the Product Data Sheet for this property when making a change. The Chain width also denotes the size of the zip. It is important to use the right size of zip in the right application. Please see choosing the right zip from our FAQ and website for advice on which zip to use.
Typical zip sizes for Opti Spiral / Metal / Plastic Moulded and Invisible zip and local market terms can be found in the detailed information on our website. See also Opti Website for Product Data Sheets.
Invisible zips, sometimes refered to as concealed zips, have a fold in the tape behind the sewn coil area so they can be sewn with a special sewing foot to give a hidden / invisible appearance to the teeth. The teeth are hidden from view. See Choosing the right zip and Do’s and Don’ts for further advice on invisible zips.
Bottom stop should be protected with a bar tack to prevent direct strain on the zip. If bar tack is fitted but breakage still happens, check effective opening of the garment. Try garment on model or dummy to see possible causes of the breakage.
Change the zip for reversed coil type zip and slider.
Spiral/coil zips have an S twist and Z twist in the teeth creating a "smile" or "frown" appearance when the teeth are joined. The left and right teeth should be both in the same direction/condition. If this is not the problem check the sewing tension is equal on both sides of the zip.
Spiral/coil zips have an S twist and Z twist in the teeth creating a "smile" or "frown" appearance when the teeth are joined. The left and right teeth should be both in the same direction/condition. If this is not the problem check the sewing tension is equal on both sides of the zip. Also check for any high levels of shrinkage in the fabric and any interlining.
Check the sewing tension is equal on both sides of the zip. If this is only noticed after pressing heck for any high levels of shrinkage in the fabric material and any interlining.
In long centre front applications the end of the zip can be placed under high strain. Check that the end consumer does not create too much pressure to the bottom end of the zip when wearing the garment. If the application is a long coat a two way zip maybe required.
Check that there is sufficient clearance for the slider to pass along the length of the zip. Check that no side seams interrupt the travel of the slider along the chain. Check that the edge fo the coil is not stitched to the base tape of the zip.
Ensure an M46 or M60 zip is being used. Ensure zip slider is closed during washing and ensure the button is fastened where ever possible. If button is not present protect the zip from the stresses of the washing process. Ensure no overloading of the washing is occurring.
Ensure an M46 or M60 zip is being used. Ensure zip slider is closed during washing and ensure the button is fastened where ever possible. If button is not present protect the zip from the stresses of the washing process. Ensure no overloading of the washing is occurring. Check if washing machine hole sizes in the drum are compatible with the slider puller. Check there are no gaps / slots where the puller can be trapped in washing or drying equipment.
Ensure an M46 or M60 zip is being used. Ensure zip slider is closed during washing and ensure the button is fastened where ever possible. If button is not present protect the zip from the stresses of the washing process. Ensure no overloading of the washing is occurring. Check if washing machine hole sizes in the drum are compatible with the slider puller. Check there are no gaps / slots where the puller can be trapped in washing or drying equipment. Check that a bar tack is present protecting the bottom of the zip.
Ensure an M46 or M60 zip is being used. Ensure zip slider is closed during washing and ensure the button is fastened where ever possible to protect the teeth with the fly piece. If button is not present protect the zip from the the chemicals of the washing process using a piece of cotton fabric. Ensure no direct dosing of the chemicals onto the zip teeth or slider. Ensure the temperature and timing controls are correctly calibrated and set to the required process conditions.
Check for any solution / sprays / polishes being used on the zip teeth. Check for any tanning chemical residues on the surface of the leather. Check that the zip has been ordered with Protecto Treatment to prevent any reaction of the pigments In the leather with the copper of the zip.
Check for any solution / sprays / polishes being used on the zip teeth. Check for any excess oil being used on sewing threads if sewn application or check temperature of heat seal if sealed zip application.
Check that there is sufficient clearance for the slider to pass along the length of the zip. Check that there is no adhesive accidentally applied to the zip teeth or inside the slider during insertion. Check that no side seams interrupt the travel of the slider along the chain. Recommended distance is 2mm from the edge of the teeth.
Spiral / coil zips have an S twist and Z twist in the teeth creating a 'smile' or 'frown' appearance when the teeth are joined. The left and right teeth should be both in the same direction/condition. If this is not the problem, check the sewing tension is equal on both sides of the zip.
Check that the slider and chain are from the same zip supplier and are the correct sizes to match one another.
Check that there is no special process such as turning out the bag that creates high pressure on the slider pushing the slider against the bottom end of the opening. Check that there is sufficient clearance to allow the slider to run smoothly without rubbing against the fabric / leather of the item or the lining of the item. Check that no side seams interrupt the smooth closure of the slider and that both slider and chain are from the same supplier. If the zip is metal, check the direction of the chain is correct. Metal chain has a correct / wrong way to mount the slider. This is called preferred / non preferred direction. If the slider is to be used in both directions, than special symmetrical teeth or two way teeth are needed.
Please inform our Customer Service department when placing orders for goods for outdoor use. For such goods, we recommend standard puller with silver plated slider, or special plastic sliders.
Please inform our Customer Service department when placing orders for goods for outdoor use. For such goods, we recommend standard puller with silver plated slider, or special plastic sliders. Outdoor goods should be dried before storage. They should not be packed away wet.
Please inform our Customer Service department when placing orders for boat covers / marine upholstery. For boat covers / marine upholstery, we recommend standard puller with silver plated slider, or special plastic sliders.