Let's say that someone's white dress is severely stained by blood. If she killed an animal just to dye her dress in the blood, would the color of the dress be uniform? After it dries out she washes it well in the river to get rid of the smell. Would it be perceived by others as not a suspicious dress? How about the color? Would it be a dull, brownish red? Has anybody ever dyed their clothes in blood? Anyone...?
It would be a gross brown, and I don't think it could turn out uniform. Think a completely brown tie-dye and that might be accurate.
Is she doing this on purpose? It would probably take more than one animal to dye a dress completely. If it's on purpose, she could probably get pig's blood from a butcher, fill an old tub with the blood outside in her yard and then put the dress inside to soak for a bit. Even then.....it might not come out uniform.
Is this a ritual thing? Or someone who just wants something other than white clothes? There are so many plant dyes one has to wonder why you are using blood? It might be difficult to get an even color with blood. Tie-dying it makes sense to address the uneven coloring. It would be brownish red, like rust. Actually rust is sort of what you end up with, oxidized hemoglobin. Cold water is one way to wash blood out though it isn't perfect. You'd want hot water to set the stain first. Yes but you can dilute it. The red cells are suspended in the plasma and they fracture/rupture in water but that is what you want if you are using blood as a dye.
Thanks for the replies. It's about a scene I'm flirting with but I'm still thinking about some of the technicalities of it. A character kills some people and gets all bloody. She wants to conceal her identity as the killer, but hasn't got a spare, clean set of clothes with her. She also can't wear their clothes. She's in the middle of nowhere basically and wants to go to a nearby town without seeming suspicious. It's set in ancient times. It's night time, and after the bloody fight she comes across a remote river side and she knows nothing about herbal dyes and she's kinda in a hurry as well. She's pretty good at hunting though. I was also flirting with the idea of using her victims blood to dye her clothes, but I'm not sure if she'd do that in general. Is it way too brutal? She's in grave danger though and she needs to move fast without getting too much attention on her.
You have to take into consideration that blood clots within the first 10 minutes or so, unless if the character uses some chemicals to prevent blood coagulation, and the blood-soaked dress would be caked and stiff. But she can soften the fabric by washing it afterwards. I don't have any experience with that much blood but I have a tiny bit of blood stain on my white BJJ gi and in the beginning it was reddish brown but after repeated washing it became yellowish brown. It is hard to remove blood stain but blood does not make a very good dye. Why not have her wear darker clothes? It helps conceal her in the dark and hide any blood stain. As far as I know, common people in ancient times don't generally wear white clothes probably for practical reasons. White clothes were reserved for high-ranked clergies and royalties.
Wrapping because, well, dried blood. Spoiler: Wrapping because dried blood I googled "dried blood on white cloth" and found a bunch of images. This one shows a larger blotch on a mattress, gives a pretty good idea of the coloration and variation you'd get.
I've had some experience with this. I was connected up to a dialysis machine and the line connected to my artery came loose. It was probably 30 seconds before it was reconnected, so there was quite a lot of blood on the bedsheet and my shirt. The shirt was blue, not white though. After washing, it's not noticeable, but that was a machine wash on a high setting with detergent. I'm not convinced a cold wash just in water would do it.
In ancient times, white clothes are probably uncommon unless the character is rich in some way. It's an interesting concept. Have you ever done laundry in the river? As long as you wash it before the stain sets, you could get it pretty clean. Your character would at least know how it is done. How to hand wash your clothes
Based on your description, she's not going to have time to do a thorough wash. She'd probably get in the water with the clothes on and then be rubbing sand or dirt on it to disguise what it is. I agree with the others, back in those days most women did not wear a white dress (even for weddings) just because it was hard to find and hard to care for. Most women in ancient times knew about dyes for clothing otherwise all their clothes would have been the same color. I would suggest taking her out of the "white" dress, and if her victims happen to be wearing a "cloak" she could use that to cover the stains. Just some thoughts.