Since turpentine is so much more volatile than OMS the extra turp you add is likely to flash off while you are working with it. That is why your medium is gumming up, the turp is evaporating. (the damar you used out of the bottle already is dissolved in turp.)
Originally Posted by pineywoods belle
And BTW, this medium is not a classic but a fairly modern substitute for copal and amber based cooked resins. As for toxicity, search on turp and damar to get all the info you need.
Thomas Jefferson Kitts