Intro

Regarding Dptek1's freeze/thaw cycle recommendation, recent evidence appears to highlight the importance of the thaw phase in broad terms of soup temperature, & duration that it remains at this temperature. The current recommendation is to "leave the jar at room temperature (not less than about 20°C) for a few hours before re-freezing".
Here we compare the performance of a multi-cycle heat bath (aka Bain Marie) / refrigeration cycle to traditional freeze/thaw using two extractions.

Freezer

This was a Liebherr under-counter model similar to this, set at and showing  -18°C on the front panel display. The centre rear of a middle shelf was used to hold the jar.

Fridge Used

 This was Hotpoint RLA 34, temp generally varies between around 3-6°C as measured by cheap Aliexpress fridge thermometer.

Thawing Out 

Upon removal from freezer,  jars of acidified bark were placed a few feet in front of a small fan to hasten the thawing process

Ambient Temperature 

Tests were carried out in early September 2026, with extraction room ambient temperature a fairly consistent (and ime almost ideal) 19-24°C depending upon time of day/night, cloud cover, and window open/closed. 

Extraction Details

Two side-by-side extractions were conducted (∴ 4 extractions in total),  all with finely powdered bark from the same 1.7 kilo bag. The first extraction used 2x100g and the second  2x80g.  In all extractions, 110g lye and 180g table salt was used as per standard DpTek1.

First Side-By-Side Extraction (2x100g MHRB)

Freeze/Thaw Sample Schedule

Bark was weighed out and 250ml 5% white vinegar stirred into it on Sept 3rd 11:40.  Acidified bark was stirred and evaluated for adding extra vinegar at each thaw (no more vinegar was added)

• Bark stood at ambient temp for 10h 43m, then in freezer for 10h 50m

• At ambient temp for 11h 51m, then in freezer for 13h 43m

• At ambient temp for 10h 42m, then in freezer for 10h 31m

• At ambient temp under fan until convincingly fully thawed (3h 29m)

Extraction then commenced by adding the bark to pre-mixed room temp salt/lye solution.  Excess heat was removed by stirring in pre-refrigerated water and ice cubes.
Added water brought the level to approx the 1500ml marker on the 2L media bottle.  Mix was judged adequately runny, and no more was added until after layer separation of the final pull (to raise level of remaining solvent).
Pulls were conducted at 21.5°C ± 1.5°C (measured by IR Thermometer before each pull).

Extraction was then continued by adding the bark to pre-mixed room temp salt/lye solution.  Excess heat was removed by stirring in pre-refrigerated water and ice cubes.
Added water initially brought the level to approx the 1500ml marker on the 2L media bottle, but being judged as far too viscous (likely owing to the bark absorbing vinegar and swelling), extra water was added to bring the level to the 1800ml marker.  Viscosity was still higher than preferred, and as expected, virtually complete solvent/soup layer separation took much longer than the freeze/thaw sample (around an hour compared to approx 10-15 minutes)
Three pulls were conducted at ~21.5°C (IR Thermometer) with light naphtha (regular panel wipe), and mixed together for freeze precipitation, drying and weighing

Second Side-By-Side Extraction (2x80g MHRB)

This second test was done to try and correct any possible yield anomalies with caused by the extra viscosity of the previous 100g Bain Marie sample.

Added vinegar was a total 250ml for both freeze/thaw and Bain Marie (no more was added to either) although extra absorption (maybe combined with some evaporation) was still noted on the Bain Marie sample.  

Freeze/thaw and Bain Marie schedules were conducted (similar to the previous test), and once completed, similar quantities of water were added as previously (water was top up to the 1700ml marker on the Bain Marie and 1500ml for the freeze/thaw). 
The difference in soup viscosities between the 80g samples was still very apparent when stirring side-by-side, although solvent/soup layers separated much faster on the Bain Marie sample, reducing it to only a few minutes more than the freeze/thaw soup.

Afterthoughts

• I'm wondering if the above freeze/thaws were actually achieving the most effective acidification stage for the particular bark sample, and maybe the Bain Marie was simply achieving the same but via another route.

• I'm wondering if different types of bark might work better with the Bain Marie than freeze/thaws Joytek. Finely powdered was used here, but maybe it'd be different for shredded

• Would Bain Marie provide a useful option in cooler winter / spring ambient temperatures, when (particularly overnight) the thaw stage may not reach over 20°C for as long as desired, or at all?

• I believe the experiment might help to clarify our somewhat vague "for a few hours at room temperature". Until we know more, maybe it'd be better to suggest something like "Around 10 hours at or above 20°C"