What a Free UV Carpet Inspection Shows

Most people book carpet cleaning based on what they can see. With pet contamination that is the wrong measurement, because the visible mark shows where the surface was affected and almost nothing about what is underneath.

Why urine glows under UV

Dried urine leaves behind crystalline deposits containing phosphorus compounds and organic salts. Those compounds absorb ultraviolet light and re-emit it in the visible spectrum, producing a dull yellow-green glow. Fresh urine glows less than old urine, because the concentration of dried salts is what fluoresces rather than the liquid itself.

schedule a technician. It means UV is best at finding exactly the contamination that matters most: old, dried, repeatedly deposited urine that has had time to soak in.

What the inspection actually reveals

What we look for	What it tells us
Perimeter of the glow	The real treatment area, not the stain size
Number of separate sites	Whether this is an accident or a marking pattern
Intensity variation	Which deposits are oldest and heaviest
Glow along baseboards	Liquid has travelled under the carpet edge
Glow on the pad through a lifted corner	Contamination has passed through the backing

Why the extent surprises people

Liquid does not stop when it hits carpet. It passes through the face fibre and then spreads laterally as it travels down, because the backing and pad resist vertical movement more than horizontal movement. The result is a cone shape: narrow at the top where you see it, wide at the bottom where it matters.

This is why treating only the visible mark reliably fails. The treated area is the tip of the cone and the untreated remainder keeps reactivating with humidity.

What UV cannot tell you

It is worth being honest about the limits. UV shows presence and extent. It does not show depth, and depth is what determines the treatment and the price.

• It cannot distinguish surface from pad contamination. That needs a moisture probe or lifting a corner.
• Some cleaning products also fluoresce, particularly optical brighteners in supermarket spot removers, which can produce false positives.
• It does not identify the animal. Cat and dog urine glow similarly, though cat contamination is usually more concentrated and more repeatedly deposited.
• It works poorly in daylight. A genuine inspection needs the room darkened, which means blinds closed rather than a torch waved around.

What to do before an inspection

• Do not apply any product in the days beforehand, since brighteners can obscure the reading.
• Note where you know accidents happened, including under furniture and from previous pets.
• be ready to close blinds and turn off lights in each room.
• Mention if the smell is worse in humid weather, which indicates salt reactivation at depth.

Why it should happen before the quote

This is the practical point. A quote given without inspection is a guess, and guesses in this category get corrected upward once the furniture has been moved. An inspection first means the number you are told accounts for the actual contamination, including whether pad replacement is likely.

It also means you find out early if the honest answer is that topical treatment will not hold. That is worth knowing before you pay, not after.

Frequently Asked Questions

What does a UV light show on carpet?

Dried urine salts fluoresce under ultraviolet light, producing a dull yellow-green glow. The inspection reveals the full perimeter of contamination, which is typically two to three times wider than the visible stain.

Why is pet contamination bigger than the stain?

Liquid spreads laterally as it travels down through carpet backing and pad, forming a cone that is narrow at the surface and wide underneath. The visible mark is only the top of that cone.

Can UV inspection tell how deep the urine went?

No. UV shows presence and extent but not depth. Determining whether contamination reached the backing, the pad or the subfloor requires a moisture probe or lifting a corner, and depth is what sets the treatment and price.

Do cleaning products show up under UV?

Yes. Optical brighteners in many supermarket spot removers fluoresce and can produce false positives, which is why it helps to avoid applying products in the days before an inspection.

Should the inspection happen before I get a price?

Yes. A quote given without inspection is an estimate that usually gets revised upward once furniture is moved. Inspecting first means the figure accounts for actual contamination, including whether pad replacement is needed.