About thinners

I can't say I've ever heard of paint thinner "going off".

Personally. I'd use the paint manufacturer's thinner exclusively for thinning the paint and use a compatible cheaper substitute for brush cleaning.

Say for example, you are using an enamel paint, use the manufacturer's thinner only for the paint and use sometihng like mineral spirits to clean your brushes.

Likewise, if using an acrylic, only use the manufacturer's thinner for the paint and wash your brushes with water (or when something a little stronger is required to clean your brushes, denatured or isopropyl alcohol)

Don't even think about thinning your paint with the same thinner you're using to clean your brushes.

Khalee2 wrote:

how long does thinner last. when do you deside that it is no longer any good. And can you use the same bottle to thin paints as well as air brushing  orwould you use a seperate bottle for both,IE one for cleaning brushes and one just for thinning paint.

This is what I do

I buy thinner at the hardware store, then transfer it to different containers depending on what I need, some containers are for cleaning brushes, some for soaking airbrush parts, others are clean thinner used for thinning paint.  I use either the Testors 1 3/4 oz bottles or any empty cleaned out paint bottle.  When the thinner for brushes and cleaning becomes unusuable, I dump it into an empty chemical resistant bottle (ie a bleach bottle) and then take it to the waste center for disposal.  

As far as thinner cooking off, I would be more concerned with the metal containers rusting and contaminating the thinner and leaks.  I have some thinner thats over 10 years old and it's fine.

What Coldiron said.

Quite frankly, thinner is thinner. If you want to spend over four hundred dollars a gallon for "Airbrush" thinner from a model paint manufacturer, knock yourself out. I've used gallon cans (under $10 a gallon) of Ace Hardware "Paint Thinner" for Model Master Enamels, Testors' Dullcoat and Glosscote, Humbrol enamels, Testor's little square bottle enamels and tube oils for decades with no problems at all. As above, I keep some for cleaning brushes until it gets nasty and some clean one to thin paints or run through the airbrush. For my Vallejo paints, I use distilled water from the local CVS as recommended by the manufacturer. If a paint requires a proprietary thinner, the manufacturer has done this for one reason: to separate you from your money as quickly as possible.