Paint mixing

Thanks everyone for the info. I really appreciate y'all taking time to answer my question. Big help 

EdGrune

Adding the thinner starts a reaction to solidify the paint

He hit the nail on the head.

Look at it this way: the manufacturer has a heavily-vested financial interest in coming up with the most stable and consistent paint formula they can. Anything that changes that delicate chemical balance starts the clock ticking toward possible strange, annoying or bad effects in the mix.

The roll of the dice is that the timing and extent of those effects is always variable...but decades of experience suggests they'll always occur at the worst possible moment...or to put the kybosh on the project you've worked hardest and sweated blood on.

As the renowned philosopher Mr. Eastwood was fond of saying:

"Do you feel lucky?"

It sounds counterintuitive.  Why can’t I mix some thinner/retarder into my bottle of paint.

I’be done it. The mixed paint hand brushed well.  No problem.  Come back in a week. Still no problem.  Stick that bottle on the shelf until later when you really need that color, just a brushfull.  Aww come on, the hobby shops are closed

Why has the paint turned into a solid hockey puck in the bottom of the jar or you may catch it when it is a pile of goo  

Adding the thinner starts a reaction to solidify the paint

go to the restaurant  supply store and buy a sleeve of 2 oz condiment cups to mix your paint as needed.  Don’t pour the left overs back in the bottle

BlackSheepTwoOneFour

You don’t want to add the retarder straight into the bottle of paint. You risk contaminating your paint. The retarder is not to be added into a bottle of paint, only to the paint in the cup of your airbrush.

 

or when you hand brush, you need to add a few drops to how much you plan to use.

You don’t want to add the retarder straight into the bottle of paint. You risk contaminating your paint. The retarder is not to be added into a bottle of paint, only to the paint in the cup of your airbrush.