Baking your media before use depends on both your process and objectives. If your current process is working well and the media performs satisfactorily, it’s best to stick with it. However, if you have the opportunity to experiment, you could try substituting an equivalent volume* of baked media for the non-baked media you typically use (*equivalent mass, if you have enough space in your CRC, but know using dry mass uses more media than its wet mass)
You might find that baked media is more efficient, effective, or tailored to your specific requirements. If you don’t already bake your media, it’s worth giving it a try. As with any good experiment, plan your work, write down your steps and measurements and define your success criteria.
Another consideration is the space and equipment required for a preprocess bake-out step. We strongly recommend having a dedicated area for media preparation. Filtration and adsorption media, including the granular and pelletized types, produce fine dust that can contaminate equipment lines and products, as well as pose hazard to individuals breathing in the dusty air.
Pro-Tip: Master Extractionist, Murphy Murri, repurposed a shop vac to act as a down draft air filter in her lab. By securing the hose to the table where she works, ambient dust is kept to a minimum. Even in the arid climate of Colorado, Murphy always bakes her media prior to use.
The Media prep area should contain a dedicated oven for drying the media. Production ovens that are used for concentrate products should never be used for media prep. The reasoning behind this is the high potential for cross contamination between dusty media and sticky concentrates.
We recommend using large, shallow pans and drying the media in layers no deeper than 2”. The shallower the layer of media, the faster it will dry. There is a bit of a balancing act in terms of streamlining production. See what works best for your lab; whether it is multiple, faster runs with less media, or a longer overnight process with more powder in the trays. Either way, many extractors will stir (specifically fine powdered) media at least one time during the process to prevent a skinning layer (crust) on top trapping moisture as it tries to escape.
Since the media is loose and can be blown around, both convection and vacuum oven use require some forethought. Whether you have a convection oven or vacuum oven, you will need to protect your powders from flying away. We recommend using a fine mesh bonnet over the tray. Make sure to select one that is made entirely of heat tolerant materials (i.e. will not melt or burn at least 50°F / 10°C above your maximum oven temperature) and has a fine enough mesh to keep the powders in place.
At Carbon Chemistry we recommend using a very high thread count all-cotton pillowcase over trays in vacuum ovens (and ONLY under vacuum at temperatures above 392°F/ 200°C). Insert the pan of media into the pillowcase and then fold the opening under the pan on the shelf. Keep in mind that heating under vacuum relies heavily on conduction. The layers of pillowcase between the pan and the shelf will slow down conduction so a higher temperature or longer warm-up cycle might be necessary (although this promotes even heating, which reduces or eliminates skinning).
Even with the pillowcase, vacuum assisted drying will be the most effective and efficient. A vacuum oven without vacuum applied is also a common choice but be aware that vacuum ovens are designed to manage heat in a vacuum and have terrible heat uniformity when operating at ambient pressure. Media on the upper and lower shelves will process very differently in a vac oven without vacuum.
Here are some guidelines to follow if you decide to bake your media prior to use:
- Keep maximum oven temperatures moderate at no more than 300-400°F (≈150- 200°C) with vacuum or 320°F (160°C) at ambient pressure. (Unless your process involving media requires higher temperatures, or you are dehydrating molecular sieves)
- Cover your trays to avoid a messy oven or contaminated/damaged vacuum pump.
- A shallower pan for the media will result in faster drying.
- Stir finely powdered media very gently at least once during the drying cycle to
break up any crusty layer that would trap moisture. However, if the media tray is covered, there is no need to stir because a cover prevents skinning.
- Store dry media in air-tight containers, or else in a desiccator or vacuum oven under vacuum or backfilled with dry nitrogen. Containers that we suggest using are Mason/Ball jars or Gamma-Lid buckets.
- Molecular Sieve Beads require a ramp and soak process for heat treatment. Starting at 100°F (≈40°C), increase oven temp by 50°F (10°C) every hour until the final processing temp of 400-482°F (200-250°C).
- DO NOT bake media that has been used to treat solvents unless the media is completely devoid of solvent vapor! Outgas media with solvent in well-ventilated air and thin layers for several days prior to placing in oven.
- Remember to ALWAYS pull vacuum before turning up the heat.
The pointers above should help aid you in deciding about preprocess bake-out implementation in your lab. Remember, there is more than one right way to prepare the media for use in extraction. The important things to consider are safety, cleanliness and consistency.
Learn more about “How Pre-Baking Media Will Enhance Your Cannabis Oil Process“.
Still curious about incorporating baking into your current process or baking in general, get in touch? We would be more than happy to discuss this and any other questions you have.