There are no standards for these products and manufacturers are free to call their merchandise almost anything. Your instructor can provide “Pro Art Odorless Thinner” at a good price. Odorless Mineral Spirits can be used as a medium in the process of painting as well as for cleaning brushes and other equipment. These products must not be used directly on the skin or on clothing for cleaning up. It should be pointed out that “Turpenoid Natural®” which comes in a green container, is a brush cleaner and not useful as a painting medium. “Turpenoid Natural®” should not be used as a hand cleaner nor used to clean paint of of clothes while you are wearing the clothes. Now let’s discuss “recycling” paint thinner. At the end of your painting session, wash your brushes in your coil jar and dry them with paper towel. Your paint thinner is now dirty and should be changed regularly before each painting session.

However since we are using odorless paint thinner it can be recycled easily at least once. I use recycled paint thinner outdoors. Clean odorless paint thinner is mandatory in the studio where 20 people stand in a room.

material you will need
2 large glass bottle ( like fruit juice ) and a plastic funnel. A pair of plastic gloves, a roll of paper towel.

Put on your plastic gloves
Close your coil jar tightly and shake the liquid inside as to remix the paint thinner with the pigment that has already started to sediment at the bottom.  Pour the entire contents of the coil jar into bottle #1, the “recycling” bottle.

With a little soap and water you can wash the coil jar and dry with a clean paper towel.  Make sure the coil jar is thoroughly dry.

Pour clean paint thinner into your coiled jar for your next session.

After a few weeks of settling , the paint thinner in bottle #1 (the “recycling” bottle) is now decanting.  The heavy pigment settles down at the bottom and the clear paint thinner is at the top. It should have the color of green tea with no particles in suspension.

Step 1.
The reason you want to do this into 2 steps is that every time you pour the content of your coil jar in bottle#1 the (“recycling” bottle) to be recycled, it disturbs the delicate equilibrium of the pigment settled at the bottom and you have a bottle of dirty paint thinner again. So you cannot harvest at the same time that you are recycling. It is OK to keep pouring paint thinner in jar number #1 for a few weeks, then you let it rest.

Step 2.
Very gently, without shaking anything, pour the clear paint thinner into bottle #2, the “recycled” bottle.
First, harvest only the clear liquid into bottle #2, the “recycled” bottle.  Watch carefully and when the gunk from the bottom of the bottle reaches the top, stop!   

To start the cycle, you will use new, clean paint thinner from the gallon container.  After a few painting sessions and emptying your coil jar into bottle #1, (the “recycling” bottle) you will have enough thinner in bottle #1 to work with.  Decant bottle #1 into bottle #2 as explained above and pour the clean, recycled thinner from bottle #2 into the coil jar.   You can also use50 / 50 recycled and new paint thinner. It should never smell. Again studio conditions require new paint thinner. Outdoors, the ventilation is excellent

Meanwhile your original gallon container is getting empty and can be used in this process later on.
It takes several years for your glass jar to be full of gunk. Bring it to the recycling center of your town, or to the curbside pick up for hazardous material.  Follow local regulations for hazardous household material like the oil from your car or other comparable chemicals.
And that’s it! and while we are on the subject, never ever ever clean your hands with paint thinner. it will go right through your skin, this is what it is designed to do. Use baby wipes. always use gloves when manipulating paint thinner like recycling process and the like.