I have seen several posts stating that Formby's Tung Oil Finish does not actually contain any tung oil. Curiosity got the best of me and I inquired and received a response from Fomby's. Response pasted below:
SUBJECT: Formby's Tung Oil Finish
Thank you for your inquiry. Here is the definitive answer: The Formby's Tung Oil Finish does contain tung oil but is not 100% pure tung oil. The Tung Oil Finish is a blend of tung nut oil and an alkyd varnish resin. Unfortunately the formula is proprietary and we are unable to provide the material composition ratios.
Sincerely, Todd Formby's Technical Service