by Jim Smith

You have likely seen this a time or two with upholstered furniture, but may have not known what it is.

You are about to clean some upholstery. In your pre-inspection, you notice a faint, splotchy reddish or yellowish, or brownish, discoloration on the seat and back cushions. Frequently, the sofa has a feather filled ticking, but not always. (Ticking is the fabric “bag” that holds the filling material.)

After cleaning, the discoloration intensifies or becomes visible. Your pH meter reveals a value around 2 on the ticking and between 2 to 5 on the face fabric.

So, you asked yourself, what caused this? Did you accidently rinse the fabric with a toilet-bowl cleaner loaded with hydrochloric acid???

The answer is that the manufacturer’s flame retardant on the ticking has deteriorated into a strong buffered acid. Your cleaning has caused the acid to wick into the face fabric which is why it may or may not have been visible before. Down feathers aggravate the situation by causing excessive off gassing of moisture.

If the pH is really low, it could cause cotton and other cellulosic fibers to become hard and brittle. Synthetic fabrics will likely not be harmed, but other dyed fabrics may have red streaks, which are due to indicator dyes changing their hue as a result of the shift in pH.


In 1953, the United States congress enacted the FLAMMABLE FABRIC ACT, and the NATIONAL BUREAU OF STANDARDS was responsible for testing and recommending flame retardant standards for various areas of textile manufacturing. This is why the manufacturer’s tag is found on most furniture’s platform. However, California passed its own law in 1975 and this new kind of flame retardant was first seen there in the early 1990s. Now it is common throughout the country.


Natural fabric that has become hard and brittle cannot be saved. Cotton has three hydroxyl groups in it and dissolves in sulphuric acid. If the fabric is unharmed and discolorations are the only issue, then clean the face fabric with baking soda (sodium bicarbonate) until the discoloration has been removed. In nearly all cases, it will take multiple applications for this to work. You can pre-spray this solution onto the fabric and rinse with it. Do this until pH readings are slightly over 7. It may take several minutes at a pH of 7 to see the change.

Mix the baking soda at 5 to 10 ounces per gallon and at room temperature. If baking soda is heated too much, it breaks into sodium carbonate, water and carbon dioxide; therefore, keep the solution near room temperature. You will know if your solution is good if its pH is closer to 8.3, a pH of 5.5 means it has totally neutralized itself.

Sodium bicarbonate is the preferred alkali of choice because it is well buffered. Therefore, it is not advisable to use other alkali since the pH may end up going too high or it may not have adequate buffering ability. Plus, baking soda is likely to be less toxic than other substances.

Since this will likely take multiple re-cleanings, the cost of doing it has been prohibitive in more cases than it has worked.

Correction that may not work

Wrapping the ticking in plastic has been an effective measure for preventing ink from bleeding into the covers, but will likely not work with this problem. The off gassing of the acid component of the flame retardant damages the dye over time, and cleaning reveals the damage, much like benzoyl peroxide.


Seeing the discoloration and measuring its pH are excellent preventions. Therefore, always take pH readings before cleaning. If the readings are around 2, then do not clean it and explain the problem to the end user.

James· Jim” B. Smith is an IICRC-approved instructor and a senior practicing inspector and part of the voting consensus of the IICRC S1OO cleaning stan­dard. His educational studies come from Texas A&M University and the University of Houston. He has been in the cleaning industry since 1975. For more information, visit his website at, call (972) 334-0533 or (800) 675-4003, or email [email protected].