That's roughly an hour drive from where I was born and grew up. I can take
notes, translate and post the full transcript to the list if you want :)

> That mine is downright medieval !!! The US Mine Safety Administration would
have apoplexy after one glance!  You can only wonder how dark it is down there
when there is no video crew in there with their electric lights! No Personal
Protective Equipment whatsoever.

The coticule was quarried since Roman times and there aren't that many veins
around so there's a chance it was indeed medieval :) And yeah, Belgium mines
weren't exactly the safest places to work in, especially old ones like the one
shown in the video.

> The two-man push-pull saw is interesting.  Note the worker setting the teeth
with a hammer, freehand!  What sort of a saw plate would this be? How thick?

The saw plate is salvaged from a broken scythe blade, and the worker is not so
much setting the teeth as making new ones (they're referring to it as sharpening
the saw but that's not sharpening). The cutting action of the saw actually comes
from the wet sand that is poured on the stone. The whetstone is then polished on
a sandstone that is lubricated once more with wet sand. Originally this was
seasonal work for local farmers, to get some more income during the winter...
this is why the saw blades were made from broken scythes (waste not want not).

Similar story with the semi-industrialized process they show next, which is
probably late 19th or very early 20th century. The swinging multiple blades
frame saw is actually mostly providing the pressure and the cutting action is
from the wet sand that's poured on the stone on a regular basis. The long strips
then get chopped to correct dimensions and are sent off to the polish.

The more modern process, using a circular saw doesn't need much explanation.
With the more modern process, thicker coticule layers get cut and the offcut is
then glued to a slate backing using resin. Resin is also used to reinforce lower
quality coticules with cracks or defects (the bit with the hot iron where they
rub a stick of resin). The polishing of the whetstone is done on a large cast
iron disc that is once again using wet sand. There are two different grades of
sand used, the rough one to finish dimensioning and flattening the whetstones.
Then the final polishing with very fine sand coming from two possible
quarries... one of which being the place where I grew up.

> Although Roy Underhill wrote of trying to "harvest" whetstones in the wild,
have any Porch dwellers actually found one?

I did harvest whetstones from the wild, there are several known spots in
Belgium, France, Luxembourg and Germany where you can easily find decent
whetstones. I still have a stash of metamorphic rock downstairs that slurries
readily and finishes edges somewhere between 6000 and 8000.

That metamorphic rock came from the back side of Trier in Germany, close to the
old slate quarries. There are several known veins for whetstones in that area...
there's an historical quarry along the Moselle between Trier and the Luxembourg
border. There are also two historical quarries between Trier and Bitburg, which
used to supply whetstones for Solingen and Remscheid. As far as I can tell, and
I spent a couple of years researching in old German books, the metamorphic rock
I collected in Trier was never commercially quarried.

I'm currently living in France, not too far from the mine where the "La Lune"
whetstones were quarried... I actually visited part of that mine two years ago.
The "La Lune" mine, the coticule mines and the Eifel area of Germany are
actually part of the same mountain range, and very rich in slate and metamorphic
rocks. The biggest activity in the "La Lune" mine wasn't the whetstones but the
slate and the activity died down when cheaper slate was imported from other
countries. I do believe the "La Lune" is commercially quarried again, but on a
very small scale (I think it's a one-man operation, similar to the Welsh slate
hones operation near Yellow Lake).

It's always worth picking up thick slates (1" or 2" thick) that have a light
sparkle to them and to wet rub them with a piece of similar material. If you get
a slurry, chances are you could use that as a hone after lapping.