A note about slurry thickener.
Play the devil's advocate.
If your say Lortone 7 inch tall barrel is spinning very slow at say one revolution per minute and you have clean water as slurry the water will certainly wash the coarse abrasive to the bottom of the barrel.
If you have a Lortone 7 inch tall barrel spinning very rapidly at 100 revolutions per minute with clean water your abrasive will certainly be well mixed due to the furious turbulence.
So I hear this additive argument constantly but no one stops to reveal their RPM.
And the speed of rotation controls so many factors in rock tumbling.
And barrel diameter is also an important factor when analyzing the effects of speed.
The arguments usually stem from the old fashioned 'do it by the book' philosophy.
The book is written for the weekend warrior that does clean outs on the week ends.
And suggests using 60/90 coarse grit that will work with clean water.
Because it is simple and easy for the average person that is not educated about ways to tweak/speed the tumbling process.
I chose to move on to much coarser grits for faster coarse shaping and it saves electricity and shortens the coarse grind.
The coarsest grit costs the same as 60-60/90-90 and even 46 and 30 grit. Why buy such fine abrasives to coarse shape hard agates ?
To roll #4 and #8 grit(and 30 for that matter) I had no choice but to add slurry thickener to suspend it.
I add 2-3 cups of dry clay to the barrel, add rocks, add grit, add water, seal the barrel and chunk it on the shafts and walk away.
Come back every 2-3 days and add more abrasive, pour a bit of slurry off and add water IF it is too thick. Easy peasy. Clean out on week end.
This gaurentees a X2 to X3 faster coarse grind. Suits me. A little effort during the week goes a long way speeding the grind.