Hey there David, we are getting ready to rebuild our manufacturing facility and I was curious your opinion on vessels for maceration/extraction. For years we've simply used 1 gallon jars, but as our batch size has increased it just turns into doing tons of jars worth of one herb, which from a QA/QC/GMP/boatloads-of-paperwork-for-everything perspective, it's a bit tedious. So i'm looking into doing some larger vessels for this, and am considering switching to stainless. Dr. Yarnell had mentioned the potential for certain metals to leech into the extract though if they're left in the vessel for too long (such as nickel). Thoughts on that? I feel pretty firm on not using plastic, and finding anything larger than 5 gallons in glass isn't really possible, + they get quite heavy and of course since it's glass, breakable. On the stainless steel side of things, do you think it really matters the shape of the vessel used, in terms of being more short and wide vs. tall and narrow? Doesn't seem like it would matter that much to me, but was curious if you had thoughts on that. The fermentation world also a wide variety of stainless vessels for beer making, and I've noticed a lot of them are conical at the bottom. I believe this is usually so you can drain the yeasty portion off at the bottom and the less yeasty portion above that. Do you think a slight conical shape at the bottom of the vessel would adversely impact maceration in any way? An example would be something like this: https://hooloodistill.com/products/home-brewed-beer-fermentation-tank-conical-fermentation-tank-304-stainless-steel-homemade-fermentation-tank-craft-fermentation-tank-for-beer-whiskeyfob-price (obviously I'd use a different top that's just solid, no hole for the airlock and such). Anyways, you've been in the manufacturing world a bit and was just wondering if you had any insights/opinions you'd be willing to share.

David said: I don’t think nickel will leaching tincture, even with longer storage, Stainless steel is pretty inert and tinctures do not extract minerals (or metals) well. Possibly high EO plants may be a bit of an issue, bit much more so with plastic. We use 2.5 gallon glass jars for smaller lots (sometimes six of them for one batch) and large stainless steel vessels for large batches they are about 55 gallons. [https://hooloodistill.com/products/home-brewed-beer-fermentation-tank-conical-fermentation-tank-304-stainless-steel-homemade-fermentation-tank-craft-fermentation-tank-for-beer-whiskeyfob-price (obviously I’d use a different top that’s just solid, no hole for the airlock and such).] if you are macerating in this, getting it out will be a problem, storing finished tincture would be fine.