https://www.youtube.com/watch?v=1LHKXjOQV7s
Cotton and most furniture now has cotton and viscose blends WILL always turn brown if the fabric is wet too long or you use something with a ph over 7ph.
Sometimes even with effort the browning can not be fixed but improved 90%
1st A product that will loosen or a emusifier is need to rewet the cellulose browning and it needs to be 7ph or lower.
Proschoice power gel diluted in a 32 oz sprayer is what i used to use---now I use 5ph encap products like safe and soft--vacaway or LST from chemaxx
2nd remove solution with many micro fiber cloths on a oscillating machine --even a dewalt square sander will work --so you are not spraying more water or solution while you work on fabric.
3rd use a reducing agent on browning ---it will be safer than peroxide---mist on
I use red vanish from vacaway but any reducing agent powder----coffee spotters or look for Streepene powder online----small amount of powder in 32 oz of water----teaspoon in 32 oz
4th use hair drier ----forced heated air to speed dry cushion or section or 3x3 area ---small areas at a time
Sometimes you have to repeat process which is better than soaking fabric again.
If you are going to try peroxide or a reducing agent you should test in a small area. 1 side of cushion would be good.
I have paid for some furniture that I turned brown back when I was using hwe----just misting vacuuming and putting brown out solution on fabrics.
Worst was 2 chennille sofas---I paid out of my pocket $6000 insurance does not pay for our lack of experience. I had to practice and learn how to clean fabrics, to re-coop my losses and I did----- I have made thousands on high end furniture cleaning but i learned the hard way
and my old employer and my iicrc classes did not teach me that------- I was just told use a fabric pre spray and "do not over wet"-------had to dig for knowledge and experiment. How do you get heavy soil off fabrics that cant be wet and do not clean up with solvent or dry cleaning?
Now I can clean anything with misting low ph encap and using many micro fiber cloths to remove soil on anything.
I hope this helps--- I wish someone could have helped me 15 years ago