Converting vac oven to freeze dryer

I’ve never freeze dried anything before but I’ll be trying it out for some hash I make and maybe some other fun stuff.

Are there any ways to tweak my vac ovens to act as a freeze dryer instead?

2 Likes

Yeah, put it in a chest freezer. Run a cold trap inline between the pump and the chamber to trap h20, after several hours you can unplug the freezer, bring the oven up to room temp, after a few hours more you can begin to heat the oven.

4 Likes

That seems like a headache. I think I’m leaning towards DIY vac chambers on dry ice

1 Like

you dont think the dry ice will the freeze the water ice like a cold trap? Possibly preventing them from leaving the product? Most freeze dryers, like the harvest right dont go much below the freezing point of h20 in the evaporation chamber.

2 Likes

How about a temp swing to encourage sublimation? I can freeze then bring up to room temp then repeat.

1 Like

you dont want the product being “dryed” to thaw at any time while there is h2o ice present. It would turn the product to mush(imagine you are drying strawberrys). Best temp is just below freezing, any colder and your vacuum pump will have a hell of a time sublimating the h2o. Think back to a cold trap protecting a vaccum pump, can the pump evaporate the ices formed?


The colder you are the closer you will be to the bottom left hand side of the chart, you see the level of vacuum need increases significantly.
your goal should be slightly past the triplepoint. close to 0*c is the sweet spot.

4 Likes

Ok so now I’m leaning towards using one of my 30 gallon horizontal, jacketed stainless steel vessels to load up with a thin layer of wet hash. I can use my chiller to sit at 0° C while I vac

1 Like

that will work, the process may take 2 days depending on the moisture content. after the first 30 hours 0*c temp can be swung above freezing to allow the last bit of moisture to leave. but your product needs to be 99% dry or better.

2 Likes

Ok so I put my different grades of hash as thin as possible on different parchment papers and placed in my DIY freeze dryer.

How hard should my vac be? And I should continuously vac correct? Will molecular sieves be enough to replace cold trap? I don’t really care about the pump I put on this rig

If you have enough seives for the h20 you are removeing you’ll be fine, the main purpose of protecting the pump is fight oil contamination, this allows the pump to perfom to it’s fullest. You will want the vaccum level as deep as you can get it, the lower it is the easier the h20 will sublimate, you will want the pump to run for the entire time.

1 Like

Ok good I left it running and went to bed! Thanks again.

1 Like

If using a vac oven and LN2 cold trap to try and freeze dry terps from fresh frozen flower, should the plant material be in a thin layer for best results? It seems like the frozen flower would thaw out pretty quick, but I saw @710st on IG with some interesting results. Any thoughts?

1 Like

Also, would breaking up the flower increase efficiency of terpene removal?

It certainly helps with providing even heat distribution! LN2 will work better. Yes you will pull all moisture content as well as terpenes so you will need to seperate them afterwards using a seperatory funnel. If you are doing live material make sure you have enough surface area in your trap(s) to avoid clogging and be mindful that water expands when cold (keep and eye on glass traps.) Couple small tips for you guys’ :slight_smile:

2 Likes

How long does the process typically take? Seems like I’d run through alot of LN2 if the process is 24 hours or longer.

How about what temperature should I increase my oven to and when?

I did a run of fresh plant material, havested yesterday, put 1600g directly into -80C freezer. This morning placed frozen plant material onto 2 trays, probably should have used 3-4 trays to increase serface area. Used liquid nitrogen in the cold trap. I’ve gradual increased temperature on the vac oven from 32-110F over the course of 5 hours, digivac vacuum gauge read from 80mtorr down to 40 mtorr (slowly going down over the course of 5 hours with occassional blips up to 300-400mtorr that went down within a minute), and there is minimal condensation on the condenser. Did i do something wrong? Or am i expecting too much? The system is still currently running.