Key takeaway
Fresh accidents are liquid — blot and treat. Old accidents are residue — treat deeper and repeat.
A fresh accident and an old one are different jobs. Fresh is mostly liquid — you can blot it up. Old is residue that has soaked in and dried — you can’t blot residue; you have to treat it.
What causes it
A fresh accident is liquid on the surface — most of it can be blotted up before it soaks in. An old accident is residue that has soaked into the padding and dried — the uric acid has set into the material.
Why it persists
Old accidents persist because the residue has had time to soak deep and set. Surface cleaning reaches the top; the residue in the padding keeps releasing odor.
What actually helps
- Fresh — blot immediately and treat the surface
- Old — find with UV light and treat deeper
- Old — expect to repeat the treatment
- Both — let the area dry fully
How to handle it
- Fresh — blot the liquid immediately
- Fresh — apply an enzymatic treatment
- Old — locate the spot with a UV light
- Old — apply a deeper enzymatic treatment
- Both — let it dry fully and re-check
Common mistakes
- Treating an old accident like a fresh one
- Not finding old spots because they’re invisible
- Expecting one treatment on a deep old deposit
| Fresh accident | Old accident | |
|---|---|---|
| State | Liquid on surface | Residue soaked in |
| First move | Blot | Locate (UV light) |
| Treatment | Surface enzymatic | Deeper, repeated |
| Effort | One pass | Often multiple |
Sources & further reading
- Uric acid persistence in porous substrates general-science
Frequently asked questions
What is the difference between cleaning a fresh and old accident?
A fresh accident is liquid you can blot; an old one is residue that has soaked in and needs a deeper, repeated treatment.
How do I find old pet accidents?
A UV light reveals old urine deposits that are invisible in normal light.
Why are old accidents harder?
The residue has soaked deep into the padding and set — it takes more to reach and remove.
Glossary terms referenced