Trouser zip

Properly Dying Zips (RFD)


Instructions for use of Zips with Cotton Tape


During the garment dyeing processes, different types of dyestuff and auxiliary chemicals are used depending on the kind of fabric used for making the garment. For example, for cotton fabrics, sulphur, reactive dye or direct dyes may be used while acid dyes are normally used for dyeing nylon fabrics. The usage of various chemicals such as reducing agents, oxidising agents, acids and alkalis is very common.

When these dyestuffs and chemicals are abundant in the process, colour change of the metal components of the zip (including the teeth / elements, slider, top stops, bottom stop and open parts) may occur and, occasionally, stain migration to the garment fabrics may take place. Also dyes and chemicals in the fabric may react with the metal components and cause discolouration (dye reaction) of the fabrics. The resulting of the colour change may vary from time to time depending on, but not limited to, the following factors:

  • Nature and concentration of the dyestuff / chemicals used
  • Temperature during the garment dyeing process
  • Duration of the processing time
  • Stain resistance property of the fabric

The zip slider should always be closed to the top prior to any washing.

Very often, the colour change reaction problem will be further accentuated when the zips are kept pressed against the garment’s fabric in wet state (or in a high humidity environment) for a long time.

Where highly conductive metal components are used, e.g. brass or copper in, conjunction with reactive dye processes, the dye chemical reaction problem cannot be avoided. For this reason, we recommend that the zip should be attached to the garment after the garment is dyed or the zip be covered or protected by the use of inhibitor chemicals.

Additionally, the garment’s fabric should be thoroughly neutralised, rinsed and dried immediately after the garment dyeing process is over so that no residual dyestuff or chemicals are present in the fabric.

Dyed zips

Coats Opti recommends to its customers that they follow the instructions in this leaflet for all zips produced with cotton tapes that undergo the garment dyeing treatment.

It is necessary that before doing any treatment in bulk, a preliminary is carried out on a sample material. Coats will be unable to accept any responsibility for damages resulting from treatments carried out in conditions which differ from the ones indicated here.

Instructions for use of Zips with Cotton Tape

Dyeing Processes

The treatment conditions as listed above have been formulated using laboratory tests carried out in specialised dyeing equipment. They guarantee the best results when used with our products. We would like to remind you that all treatments must be carried out on closed zips.

Please account for the likely 5% (maximum) shrinkage that cotton undergoes when subjected to the above treatment.