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Discoloured Sealant; what are the causes?

Discolouration of sealant or "yellowing" is most commonly visible between a couple of days and a couple of weeks after application. There are several possible reasons for this, the most common ones are:

  • Exposure to chemical fluids
  • Exposure to chemical vapours
  • Exposure to smoke which has a staining effect e.g. cigarette smoke
  • Lack of UV light
  • Use on bitumen, EPDM, neoprene or wax containing products

The majority of internal yellowing is caused by exposure to chemical vapours or fluids for example the application of an epoxy floor coating whilst the sealant is curing frequently effects the stability of sealant colour. If there is external yellowing, ventilation is not a factor and provided the sealant is not being applied to a surface containing bitumen, EPDM, neoprene or wax the most likely cause will be the chemical fluid used during finishing. For example the use of a solvent based cleaner on UPVC before the sealant has fully cured.  

If you can foresee exposure during application and curing to anything that has been discussed please contact us and we can recommend a sealant which will be resistant to this exposure.  

discoloured sealant