The temperature of our rosin press plates will vary with different starting materials and desired results. For this reason, you'll have a hard time finding a one size fits all approach. So we adjust our rosin press plate temperature according to the situation, ranging from 165f-240f. We never want our rosin press plates over 240f. At temperatures higher than 240f we start to decarboxylate our oil and lose terpenes fast.
From what we've seen the lower our rosin press plate temperature is the better the oil but the yield is poor. As we raise the temperature of our rosin press plates we see an increase in yield but a loss of terpenes and the oil can become darker. If the yield is a concern when pressing dried herb rosin, we start at 240f and working our way down by 5-10 degrees at a time. This way we know what the max yield is we can expect from that material. We like to test 5 grams of dried herbs in one gram increments starting at 220f working our way down by 10 degrees at a time. As we work our way down the temperature scale we can pick what temperature works best for our materials and desires.
If we're using extracts as our starting material, we do the same thing as we do with dried herbs but our highest temperature would only be 220f. We don't like going over 220f when using extracts, the risk of losing terpenes may be higher than the reward of a larger yield. In fact, we like to keep our rosin press plates at 180f when using extracts but some even say that's too high. We've seen people keep their rosin press plates at 165f and achieve great results but it's really all about the starting material and preference. No matter what the starting materials are generally lower temperatures equals a better nose while higher temperatures have bigger yields.