Hi. This will be my first post instead of an introductory one. But don't worry, I will make one of those too.

I decided yesterday to try an Acid/Base-tek for the first time. I have done a lot of STB:s with powdered bark. But since my equipment doesn't allow for larger batches than 100g or so the logical solution was to make an Acid/Base-extraction and evaporate the acidic water to a manageable amount so it could fit in my sep.funnel. I did a test-run with powdered bark and it worked fairly well considering it was my first try, about 0.6-0.7% yield. It's no quality bark so it seems reasonable.
What I have found with all my extractions is that dealing with powdered bark is a tedious job, grinding it, involuntarily snorting it and trying to filter it off or dealing with the thick base sludge.

My question is: Can I do an acid cook on the whole bark pieces and suspect a proper yield or will this be futile?

The plan is to boil/heat it for a few hours, steeping overnight and then boiling it again over the course of the next day, totaling 3 times. Has anyone tried this before? I did a search both here and with Google with no reasonable results.

Best Regards.

I thought I would post the results of my experiments with the whole bark acid cook.

500g whole bark(pre shredded in 1x3cm bits)
2L Water x 3 at pH~2

1. Boiled the bark in 2L acidic water for 6h. Let sit overnight. Boiled for 2 hours 12 hours later. Collected the red water and reduced to 2dl on low heat.

2. Boiled the bark in fresh water for 2h x2. Collected and reduced. Saved total 6dl red water.

3. Basified the red water to pH 12-14 with NaOH. It turned brown/black.

4. 3 pulls with Heptane and yielded aprox. 1.5g off-white powder. 0.3% Yield. Probably some product left in the base-sludge. Saved the sludge in HDPE-container for collected sludges to do a big heptane pull when full. I save all my STBs in a big jug so to really squeeze out everything.

I must say using whole bark gave a yield in the very low end and my recommendations is to pulverize the bark when extracting. I will probably not do any more A/B-extractions since this seems like a failed project for I can not use whole bark which was the whole point. There was a few more steps and the overall quality of the product did not surpass the ones I get from STBs. I used a new batch of bark and will of course do an STB to verify the quality of the bark.