How do you remove set pet urine from carpet?
Urine contains salts that have the ability to act as a desiccant. That is to say, it can attract and hold moisture better than carpet. If you pass a moisture meter over a urine infected area, even if it has been left to dry for months, you will find that the area where there is urine will have a higher moisture content in relationship to the surrounding carpet. This is the reason urine odour is stronger when the humidity in the air is elevated. This ability to attract and retain high moisture in carpet creates ideal conditions for bacterial, viral and mould growths. Removing urine salts from your living area is critical from health and indoor air quality perspectives.
If you have a blacklight this will enable you to find dry fluorescent reflective material but it does not necessarily mean that urine is present in the carpet. It must be substantiated by odour identification (smelling the carpet) coming from the illuminated area or verifying it with a non-puncture moisture meter (preferred).
Once you have located the urine, take a very close look at the carpet under the blacklight to determine if the urine is on the tips of the fibres or if it has gone through the carpet. If it looks like it has gone through the carpet you will have to lift the carpet and repeat this process to determine if the underlay and sub-floor are affected.
What has to be done
If the underlay and sub-floor is affected you will be:
17.22 degrees Celsius">1 8211; replacing all affected underlay
16.67 degrees Celsius">2 8211; replacing all affected wood tackless strip
16.11 degrees Celsius">3 8211; treating all the affected back of the carpet with a urine removal product and steam cleaning the carpet back
15.56 degrees Celsius">4 8211; steam cleaning and possibly painting all the affected sub-floor to seal in the urine salts
15 degrees Celsius">5 8211; treating all the affected face of the carpet with a urine removal product and steam cleaning the carpet face.
Urine & feces have the ability to bleach the colour from nylon carpet. In many cases the yellowish brownish stain appearance is the colour of the exposed nylon fibres after the colour has been removed. At this point you are not looking at a cleaning solution.
I recommend that you contact an IICRC certified firm in your area to come do the work. Restorations of this type can be complicated, time consuming and problematic if you do not have the right commercial equipment or materials to properly do the job.
As far as recommending a cleaning method in the future, you should be immediately and thoroughly rinsing the carpet using a carpet cleaning machine and standard carpet cleaning compounds. It is important that the area be cleaned immediately and not left to dry. The longer you leave it the greater chance the carpet has to have the colour bleached out.