You can reverse this by having the carpets cleaned professionally.
Carpet yellowing after cleaning.
This is basically a reaction that your carpet has all the time if it has butylhydroxyltoluene or bht in the carpet padding or glue.
You need a low ph acid cleaner of about 2 0 to safely remove the brown discoloration from your carpet.
Place one or two dehumidifiers in the room.
If you found yellow streaks on your rug after cleaning there s no need to fret.
The other affect that you might see is called phenolic yellowing.
The technical reason is that bht butylhydroxyltoluene which is a preservative used on the backs of many area rugs will let out the bht gas.
The gas gets trapped under the rug instead of dissipating into the air.
This in turn causes the fibers of the carpet to turn that yellowish or tan color.
You can remove the stain using an acid rinse extraction cleaning isopropyl alcohol vinegar and citric acid among other methods.
Another possibility is that the owner has been using some type of high ph spot remover which could turn the carpet a brownish tinge after cleaning especially with a high ph traffic lane cleaner being used.
The kind of yellowing is noticeable because it is a very bright canary or legal pad yellow.
This is very prevalent with rubber backed rugs.
It should soak up the moisture from the carpet along with the nasty smell.
If the spots are dry skip this step and move on to step 3.
Application of after market stain resisters in the hands of the carpet cleaner will still cause yellowing or browning.
One of the causes of this discoloration is a condition called cellulosic browning.
The carpet cleaner pitch to consumers of on site stain resist treatment is simply a hyped sales gimmick to.
Carpet can turn yellow from normal stains chemical stains or phenolic yellowing.
In order for this discoloration to develop several factors must be present a cellulosic fiber moisture and slow drying.
Step 4 hire a professional carpet cleaner if the discolored area of carpet remains after shampooing.
If the discoloration is still present but to a lesser degree shampoo the area a second time.
Professional carpet cleaners have access to equipment and cleaning solutions that the public does not.
Step 2 use a wet vacuum to suck up the water and cleaning solution left behind from the previous carpet cleaning.
The bht is fine as long as it has a way to air out.
It was traced back to the cushion and pressure from the mills put an end to it.
When stain resist carpet came into existence many yellowing discolorations appeared especially after cleaning.