Doing your own freeze-drying

[sparrowhawk1]

So the tank ( pressure cooker) had water in the bottom of it?

[Cowboy Sailer]

No liquid water in the vacuum chamber (pressure cooker) just a small amount of water vapor. The pressure in the vacuum chamber was not a hard vacuum but it was still well below atmospheric pressure so I had to vent it to open the lid of the pressure cooker. You know that half a vacuum is still about 7 lbs per square inch. That is a low of force holding a 10 or 12 inch diameter lid on the pressure cooker!

[RaymondR]

If you have a compressor you may be able to use one of the venturi type vacuum pumps to create the vacuum with less chance of sucking back oil from the compressor.

[Sea Frog]

Just to inform. Harvest is having a contest right now, 3 winners will get $2000 discount off their domestic freeze dryers. And it is not limited to US residents!