I’m having real problems getting stuff out of shredded bark. Solvent is hexane heated to 50Cish. The bark just doesn’t seem to start turning to sludge very quickly. Attempts of powder it in a blender (just spun around) and coffee grinder (jammed it immediately) have failed. Next step is to try to blend as a frozen block of ice.

Attempt 1:
as per instructions though due to circumstances (flatmates) acid cook was with no heat and left 24hrs
Pulls 1 & 2 were after 12hrs and quite clear. Yielded very little.
Pulls 3 & 4 after 24hrs with much more vigorous agitation (agitate 30s, stand 10mins x3) greenish and a bit cloudy. OK yield.
Pulls 3 & 4 after 36hrs with much more vigorous agitation greenish and a bit cloudy. Lots of orange goo which RXed gave some reasonable yield.
Total: 0.7%

Attempt 2:
Different bark supplier. Acid cook 8hrs heated this time but had to replace 1/3 of the water half way through due to container incident.
Pull 1 was done at cooling after 2hr heat bath. Totally clear, nothing at all after evaping half and 12hrs freezer.
Given this, pull 2 will be done after a long wait

Am I just wasting my time with freeze/thaw and acid cooks if the bark is only going to yield anything after sitting in base for days on end? Should I just go STB and salinate with a long wait?

For attempt 3 I froze the bark/water then let it thaw half way. I then drained off any liquid and broke the frozen mass into small chunks. I batched the frozen chunks with some liquid in a 600W blender. This created a frothy lumpy mimosa milkshake which I have re-frozen.

Fingers crossed.

To give appropriate advice, I need to know if you are using MHRB or ACRB. For MHRB, I would definitely recommend an STB. Also, what acid are you using?

It is MHRB. Acid is distilled vinegar.

The partially-frozen-in-water + liquid in a blender seems to have done a reasonable job. The result was milkshakey but still with solid lumps of stands. The previous one is at 72hrs baseified (+ the acid and salt obvs) for 72hrs and does now seem to have broken down. Damn this stuff is tough!

Can't really help on your low yields, my friend used MHRB with Cyb's Salt Tek and got 2%, which I thought was good.

On the bark front, my friend finds freezing and thawing a couple of times helps make it easier to grind into more or less powder. Plus a pretty powerful blender (he uses the smallest Nutri Ninja Auto IQ, which is well up to the task) always helps. You do need plenty of power and good blades.

I think the low yields have also been a combination of bark and insufficient agitation. I read a lot that said to be gentle and worries about emulsion layers but vigorous agitation for 30s and the stand 10mins x3 and the hexane is coming out less clear.

If you are using a lot of lye there is no need to worry about emulsions. Shake away