When I came back a few hours later, the brush cleaner had "wicked" it's way up the brushes and had started dissolving the paint on the handles. It was one giant sticky mess of bubbling paint, with all my nice brushes stuck together into one big mass. My Stevenson brand brushes were the worst affected and the blue handle paint was everywhere. What a giant mess!! I managed to pull all the brushes apart, getting blue paint-covered hands and arms in the process. Then taking the entire roll of paper towels, I took the brushes and cleaner out on the porch and spent the next couple of hours meticulously cleaning up my brush handles. I poured the last dirty liquid into the back of my garden - I wasn't going to put it back in the bottle or pour it down the drain.
Now my "good" brushes look like this.....maybe it's time to buy some new "good" ones.