How To Remove Acrylic Paint From Polyester

Your question is very interesting.  Acrylic paint is a very problematic stain.  While wet it is water soluble, but once cured (dried) it is insoluble and therefore permanent.  So it may be too late to get a dried acrylic paint stain out of your blue jeans.  But I can share some tips that can help you in the future if you get this type of stain again.  Ideally you’ll be able to get to the stain immediately while the paint is still wet–you’ll have a very good chance of working the stain out.  Here’s a good approach:
 

• scrape away as much paint as possible to reduce the amount of material you need to remove.
• rinse the stain with a little warm water from the back (if possible) to prevent paint from getting rinsed into the fabric instead of away from it.  Rinsing from the back isn’t always possible–pant legs for example–but it’s always a good goal.
• Pretreat:  apply liquid laundry detergent directly to the stain and rub it in, saturating the stain, and then rinse with warm water.
• repeat the pretreating and rinsing step until the stain is all the way out–3 or 4 applications and rinses should do it.
  

One of the problems with acrylic (from a stain removal perspective) is that it dries quickly, so you can’t wait too long to deal with a stain.  But if you drop everything to deal with a stain while you are painting you’ll have brushes with paint on them that are also drying out, so it is understandable that dealing with a stain quickly is in itself a challenge.  That said, you could experiment with scraping away spilled paint and applying liquid detergent that’s free of colorant or brighteners to a stain and then waiting until it’s a little more convenient to complete the stain removal steps.  You can’t wait indefinitely–laundry products used to pretreat should never be allowed to dry on fabric–but this could buy you a little time.
 
Once dried, acrylic paint is permanent on fabric because it’s insoluble in water-based cleaning solutions.  Unfortunately, solvents that could dissolve acrylic on hard surfaces shouldn’t be used on fabrics that will end up in a clothes washer.  Clothes washer and dryer manufacturers don’t want fabrics with solvents (acetone, paint thinner, etc.) on them going into their appliances due to a risk of spontaneous combustion.  They actually put warning on the appliances and in the user’s guide about this.

I wish I had a better solution for your blue jeans.  Hopefully the information will be useful if you encounter acrylic paint stains in the future.  Please let me know if you have any other questions, and thanks for writing.

–Dr. Laundry