Try using the full dose of detergent! Just kidding, of course, because I know you always do!

I would try a long soak (24-hours or more) in a strong solution of Borax or washing soda. (Usual "test first in hidden place caution".)

It may also be that the pH of the urine has long-since reacted (unfavorably) with the dyes and/or fabric and nothing will shift it.

There are some proprietary products sold for removing old, set-in, pet stains, Nature's Miracle and Get Serious are two I use. I think they both claim satisfaction, or refund. But at least one says use it first, and therefore might try to weasel on those grounds if unsuccessful.

I am sorry you have stress over revealing an old, previously unnoticed, pet stain. As you might guess I am a laundry-mane so stains stress me, too, but I also have nine (previously feral or abandoned) indoor cats, so I know it happens to the best of us.

Not to add to your angst, but you probably have more spots. A blacklight will reveal them if you care to search.

Good luck.

L.

@ liriodendron

I have four dogs and four cats. I'm afraid my house would look like a murder scene if I hit it with a black light! This is the first time I've encountered a stain that I just couldn't remove. I see urine stains on my pet bedding once in a while, and those stains always come out in a simple warm wash. This one stain, though, is not behaving like it should. My god it's just pee! Not like it's some weird exotic stain or anything...

Have you tried using a vapor cleaner on the stains?

Have you tried using a vapor cleaner on the stains?

What's a vapor cleaner???

"What's a vapor cleaner?" Maybe one of those portable home steam cleaners?

Here are examples of vapor cleaners: Vapor Cleaner Units

They range from the very expensive to the least expensive, but less effective handheld units you've seen advertised. Better vapor cleaners have higher temperatures, and pressures. If you know someone with a handheld unit you might try to borrow it and test it on those spots. The difference between a vapor and steam cleaner is that a vapor cleaner has substantially less water content released at the end of nozzle.

I remember reading on some detergent company or detergent association website that hot water is what actually sets the urine stains and they recommended using warm water washes instead of hot for underwear, including underarm stains. Something about protein stains versus whatever.
Pat

Boil some water in a kettle and then pour the boiling water on the stain. It will take a few times of doing this, then launder again. I am assuming you haven't placed the duvet cover in the dryer at any point yet. The dryer would set the stain for sure and would be near impossible to get out at that point. If the boiling water and laundering doesn't do the trick, the last resort would be to pour straight bleach on it. Let that sit for a few minutes, then launder.

Go to the pet store and pick up some Nature's Miracle. The stuff is made specifically for animal urine. Try a high concentrate (right from the bottle), wet it well and let it dry for 24 hours. Lather, rinse, repeat.

Don't use straight bleach! It will eat away the fabric.

Mix a solution of powdered oxyclean/water in squirt/spray bottle and saturate the stain. Let sit and resaturate if necessary then wash using oxyclean in the wash. If you have access to Charlie's soap, spray the liquid onto the stain and wash using Charlie's soap and oxyclean. The oxyclean pre-wash for stains works well also, but it seems as though you've just about tried everything already. In my experience if it doesn't come out with Charlie's soap and Oxyclean -- it might just be a lost cause.

Update - I have soaked the stain in hydrogen peroxide right out of the bottle... I've let it sit in oxy/percarbonate... made percarbonate paste and rubbed it on the stain... let it soak in Clorox 2... sprayed it with Nature's Miracle... re-washed at 140F... STAIN IS STILL THERE!

All I can say is that the acid in the urine must have chemically reacted with the cotton fiber, changing its underlying color. Nothing is getting out these stains. The fabric is clean - there is absolutely no odor or residue of any kind. It smells nice and clean, except for the yellow stain. Oh well, time to make some rags...

The one thing that may still work on this stain is lengthy exposure to direct sunlight. I had similar stains in my patio enclosure and nothing seemed to lift the stain but eventually (a matter of a couple weeks), the ones exposed to direct sunlight disappeared! I remember as a child growing up in the 50s we used to set our machine washed white Keds out on the lawn to dry and the sunlight almost always removed the stains that the washer didn't. I hope this helps.

EllenSu, that is exactly what we did when I was younger with our Keds. Thank you for the wonderful reminder.

I use a product called "Awesome" from the Dollar Tree. It is the most awesome (pardon the pun) laundry product I've ever used. It hasn't failed me yet. Just a week or so ago it got two week old dried blood out of a white sock. Can't even tell it was stained.

If you have the availabilty of a Dollar Tree, I highly recommend trying it! It is in a spray bottle and is a yellowish color.

Good luck!

huh?