Pro's Corner

What Makes Urine Glow Even After Cleaning?

Does this sound familiar?

You’ve used your UV or black light to identify pet urine stains on your client’s carpet.

You have treated them, and there is no longer a visible stain or any odor.

Yet, under the UV light, the spots continue to glow.

When you return to this home in the future, will you be able to distinguish new stains from spots that you have already treated but can still be seen under black light?

What if the homeowner looks at the carpet under UV light?

Will she think that you failed to remove the stains?

Is it possible to remove all traces of fluorescence even under a black light?

Family lying on a carpet with tablet in the living room

Two Elements of Stains that Glow or Fluoresce are Proteins and  Alkaline Salts

It takes very little protein to cause a glow under UV light.

Maybe you have seen one of those CSI shows where they put on amber glasses and use the ALS (Alternate light source) to find the tiniest speck of blood or some other body fluid that includes protein.

If you use a urine pretreatment and flush with a water claw extraction tool to dissolve the salts you will correct the issue but not remove the glow.

  • For urine deposits that have penetrated into the backing or that may even reach into the cushion (pad) or floor below the carpet, use a powdered oxidizer according to the label directions to achieve ideal results.

  • Clean lighter stains that are primarily on the face yarns with an alkaline pre-spray appropriate for the carpet to dissolve the proteins and rinse with an acid to neutralize and extract the alkaline salts.
Beautiful dog sitting down - isolated over a white background

salt and protein are dissolved in your cleaning water and evenly distributed.  Even if you remove 80% of the soil and cleaning solution (a very high percentage) you are leaving more than enough protein and salt behind to cause the glow.

Helpful hints to further reduce but not eliminate the fluorescence

1) Flood with as much water as possible. This dilutes the proteins and salts in the wastewater.

The Water Claw tool will assure water removal.

For items like rugs and cushions, you can apply the acidic urine pre-treatment and the water to the front at the same time you are using the spotting tool to remove the water and soiling material from the backside.

2) Remove as much of the water (plus soil and everything else that is in it) by extraction. Any water that dries by evaporation, either naturally or with an air mover, will leave all the impurities behind on the carpet.


The additional two steps listed above when used with top-quality products are the best you can do to reduce the glow of whatever is left behind.

You can add a UV absorber to the glow spots to hide the fluorescence, but this can only be added during the next cleaning.

It is better for you to explain the reason for the fluorescence than to explain the additional glowing after your cleaning is hidden by someone’s previous efforts.


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