Vince, all the old timers I remember at the marina used paint thinner. I never heard of turpinoid or Master's Brush Cleaner until I read this thread. I will have to hunt some down and try it, sounds good.
In the meantime, here's how I have been doing it:
I use two rags (old hand-towels) and a few ounces of paint thinner (mineral spirits). Wearing nitrile gloves, smoosh as much paint as possible out of the brush with one of the rags. Then dribble some spirits into the brush and keep going using the same rag. Just a small amount of spirits really loosens up (dilutes) the paint a lot, making it transfer to the rag more easily. After a few iterations of this process, the towel starts picking up less and less paint from the brush. Then switch to the clean towel and keep going. Pretty soon the towel will stop picking up any visible paint. Lastly, I smooth the bristles and carefully wrap the brush in a paper towel to keep the bristles from splaying out as it dries. I have heard that old-timers also used combs to work the paint out from deep within the heel of the brush, but I have never tried that. I just make sure to be pretty aggressive in working the paint out from deep within the brush. I usually paint my duck boats with a 4" brush, and I'd guess it only takes 4 or 5 ounces of spirits to clean it. If done carefully, none of the paint or spirits ends up on the floor, and there is no jar of dirty spirits to dispose of later. I hang the two towels out as if on a clothesline to dry. When dry, the towels are somewhat stiff, but they can be reused to clean the brush several times. I have been using the same brushes through four or five complete paintings of my boats, usually two coats each, and I'll still be using them next time I'm painting.