You don't say what color the couch is. I am assuming it must be a light color as it probably would not be very noticable on a darker color.
This stuff has always worked wonders on my leather furniture, saddles too. It's amazing actually!
Leather CPR : Leather CPR - 18 oz. Inverted Bottle [CC-18QC] - $20.95 It leaves leather looking like new, and beautifully conditioned. Infact it works so good they will probably thank you.
You should probably be able to search the site and find a store that carries it near you. I find it at a local large supermarket and my local farm/feed store too.
Now,... after the treatment, are you going to say that the couch looked like it was a little dry and in need of a little cleaning and conditioning? Or are you going to tell them you dripped, and went to alot of work to clean it up? Tee, hee!
Let us know how it works for you, I'm sure you will be amazed.
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buy enough to do the whole thing, and also any other matching furniture. As it will look like a new couch and beautifuly conditioned to stop drying, cracking, and STAINS.