For this exercise I prepared some outdoor GSC flower broken up by hand and separated into 7g bags for a control sample and for each test.  I chose a 7g sample size because it’s representative of what many people may decarb at home for personal use and the results will be consistent with the larger volumes when executed properly.  When processing larger amounts you must make sure the cannabis is not in a thick or compressed layer that would hinder heat transfer and cause unequal and incomplete decarb.


Ovens are notoriously unreliable for temperature accuracy, and to my disbelief, during this exercise I found my Across International vacuum oven was actually off nearly 30°F whereas the oven in my kitchen was spot on.  Here are some things you can do to make using the oven more reliable for decarbing:

  • Before using an oven for decarbing, determine if the internal temperature of the oven matches the temperature you intend to base your decarbing.
  • To measure the accuracy of your oven temp you can put a measuring cup of water in the oven with a thermometer or use an inferred temperature gun to see what the oven temp measures.
  • Remember the areas of the oven that deliver heat will read much higher than the rest of the oven, if possible measure the temperature of the rack, grate, or pre-heated cookie sheet.
  • When checking the internal temperature of the oven or preparing for decarbing, before measuring the temp or beginning a decarb, allow the oven to settle for about 20 minutes after it indicates it’s up to temp.
  • If the observed temp in the oven differs from the actual setting you can either note the difference and adjust the setting accordingly to achieve the desired temperature. For example if your target temp is 240°F but the oven only measures 220°F, try setting 260°F and see if it settles at 240°F and if it does use that correction going forward.  The other option is to use the measured oven temp as is and adjust the decarb time accordingly.
  • If a cookie sheet is being used, make sure it’s preheated with the oven and up to temp before putting anything on it to process.


  • 240°F for 60 minutes – 100% THC conversion, no CBN conversion
  • 260°F for 40 minutes – 99.5% THC conversion, no CBN conversion

I’ve been developing a feel for working with sealed mason jars for decarbing for a while.  Like the vacuum pack test, evaporated terpenes are trapped in the jar and re-condense on the glass surface as long as you don’t open the jar until it’s fully cooled.  Then, you can use the jar to do your infusion or extraction and collect all the desirables that would have otherwise been lost.  After the jar cools I put it into the freezer, and use the same jar for doing frozen qwet (Cannabis Oil QWET Extraction Battle of the Wash: Dry Ice vs. Freezer).  The big bonus to this method is there is no smell at all, it’s all contained in the jar.

This process has a couple operational considerations that require attention.  First, a cool jar will require ramping time and uncertain heating, so it’s important to pre-heat the jar.  The jar can be brought up to temp along with preheating the oven.  When it’s time to put the cannabis in the oven, remove the pre-heated jar from the oven, quickly load the cannabis into the jar, secure the lid on the jar, and place it back in the oven.  This process also provides the added advantage of creating a natural vacuum seal later when it cools and before going into the freezer.  Second, the jar shouldn’t be filled too much, it’s best to leave quite a bit of head room to allow even heating of the material.  I usually don’t fill the jar more than 1/3 full at most.  If I do put more in I rotate the jar half way through the process to ensure even heating and add a few minutes to the total time to make up for opening the oven and losing some heat.  Third, I lay the jar on its side to expose as much surface area as possible.  Lastly, glass in a dry heat environment requires caution and you must use your own judgement on if it is safe or not.  I have not had a single failure to this point, but it’s important to understand the possible risks of breaking glass due to temperature changes before trying for yourself.