For those artists who wish to make their own paints, mediums, and varnishes, an excellent resources is Kremer Pigments. http://kremerpigments.com/shopus/index.php?lang=ENG
This company sells an astonishing variety of rare and extremelly hard to find materials. If you make varnishes that are known to become brittle, where else could one find plasticizers such as gum elemi? Every purchase that I have ever made has arrived in timely manner, and packaged very well. Every product is also of the highest quality. Great prices as well!