2 inch European Professional Flat Paint Brush - Natural Bristle Wooden Handle - for Acrylic, Chalk, Oil, Watercolor, Gouache, Stain, Varnish, Wax & etc. - for Art, Kids, Walls, Details & etc.

Q: Are these suitable for oil picture panting

Probably not, but I suppose you could. I bought them for interior wall/trim house painting. I think they are more for acrylic based paint.

Q: Does Using them with acrylic paint and washing them with water ruin them?

It says in the description acrylic is ok to use. Water will not harm the brush. I have used them with water based latex, shellac which uses alcohol as solvent, and oil based paints that use turpentine as solvent with no issues. It's a good idea to first soak the brush in whatever solvent is going to be used for cleanup so the pores in the bristles are filled. This will make cleanup easier and complete. Also, dedicate the brush for whatever type of finish it is first used for, just like any other brush. This will prevent caking and weird adverse effects on the finish. I write with marker on the handle so I don't forget.