How can I get Polyurethane Gloss out of paint brushes?

I'm staining my hardwood floors and using a Fast-Drying Polyurethane Clear Gloss for the finish/top coat. After putting the final coat down I let the brushes soak in a jar filled with paint thinner. So far they've been soaking for three days and it's still not coming off. I'd rather not buy new brushes if I don't have to. Is there anything else I can try to get it out of them?How can I get Polyurethane Gloss out of paint brushes?
Go to the paint solvents section of your local hardware store, and get MEK, or Methyl Ethyl Ketone.





Soak the brushes in MEK, and the polyurethane should dissolve, even if the polyurethane has dried.





If there is glue holding the bristles in the brush, the glue might also soften. But at this point, you might end up buying new brushes anyway. It's worth a try.





MEK is a VERY volatile solvent, and you should always use care when working with it. The fumes from this solvent will strip the paint from anything that gets too close to it, so don't leave the can sitting next to the fender on your car. Use it in a well-ventilated area. And if you have rags with MEK on them, DO NOT throw them in the trash. They can spontaneously ignite. Soak them in water.How can I get Polyurethane Gloss out of paint brushes?
What I have always done is to purchase the cheapest brush possble to do the job and when finished for the day, throw it away, not worth the time and trouble to clean it. Start the next seeeion with a new brush. Or try to do the whole job at one time. Just a thought, there should have been ';clean-up'; directions on the container.
gas, turpentine