How can I get a mark from a blue pen out of a white cotton duvet cover?

Buy Grandma’s Best. you can get it at Hobby Lobby or online. put a drop on the spot, put a drop of plain water on it, and rub. you can try scratching a bit with your fingernail, but don’t damage the fabric. it’s best to launder it before it dries.

Let the item air dry and check the spot. If it’s still there, retreat it.

Grandma’s Best Spot Remover
https://www.amazon.com/Grandmas-Secret-Spot-Remover-Ounce/dp/B01KG76NRU/ref=sr_1_2?dchild=1&keywords=grandma’s+best&qid=1633732909&sr=8-2

Classic ball point? Aerosol hairspray. It really does work. Spray, wait 10 seconds, rinse the spot with water rubbing the area. Let air dry (heat dry can bake in a stain). Repeat once more if necessary.

Different ink would mean needing a different solution.

Ball point? Pour denatured alcohol through stain. Rub in petroleum jelly. Sponge with non-flammable dry cleaning solvent. Soak in detergent solution. Wash with detergent and bleach safe for fabric.

@kritiper The petroleum jelly doesn’t leave a grease mark?

Yes, it’s ball point.

If you try the hairspray make sure it is NOT alcohol free. I think the alcohol helps remove the pen.

Alcohol free has more water and a different chemical and is a newer product, because someone decided alcohol dries out hair (doubtful). It’s old fashioned hair spray that works.

Isopropyl alcohol. Apply from back side and blot.

I once had a white tee shirt that I got ballpoint pen on, and I took the tee shirt to the dry cleaner. The lady at the dry cleaner told me not to spend my money getting the shirt dry ceaned, but to go to the store and buy a bottle of the floor cleaner Lestoil. Lestoil is a degreaser, and has a “floor cleaner” smell. It worked like a charm. It did make the shirt have that floor cleaner smell (like Pine Sol kind of) but I washed it one ore two times more to get that smell out. It’s cheaper in the store than it is here on Amazon, but here’s the link so you can see it. Not every store has it, so if you’re looking for it in-store, you may have to shop around.

https://www.amazon.com/Lestoil-Heavy-Duty-Multi-Purpose-Cleanser/dp/B0036B89US

@JLeslie I got this from a cook book so I’d say no.

You can try Resolve carpet foam, but white dial soap will probably be better. Then there’s always bleach.

Bleach won’t remove ink from fabric.

Neither will most soaps.

Try hairspray?

grandma’s best. I use it for all such things, even on blood that has been dried and washed before. The fresher the stain, the easier it will be to remove.

The link is posted above.