According to Testors MSDS sheet its 50% mineral spirits and 30% naphtha the other 20% n-propoxy propanol plus 1% of another ingredient which you probably only can get in a 55 gallon drum. For me I use 50% mineral spirits, 30% naphtha and 20% lacquer thinner with both Testors and Humbrol enamels. If you have any misgivings about lacquer Thinner try Turpentine or vodka.