A huge iron mortar & pestle for ID and comments

[fernando]

Bought this one today in next town flea market.This thing is no kids toy !!! I had to ask the neighbour to help me carry it up the stairs to the apartment.
The mortar weighs 32,8 Kgs. and the pestle 8,4 Kgs. (total over 91 pounds).
Apparently the mortar was made in two halves, judging by the seam, using with whatever techniques. What do you guys say ... cast ?
And the pestle ball; also cast ? There are three 'marks' in it, each one apparently for a different reason. Could the round one in the side be the mold venting sprue ? The other round one in the bottom; could it be result of the ball having been drilled all way through to secure the handle ? And that (sort of) figure 8 'flaw'; could it be the makers mark ?
The seller says this was a pharmacy tool to crush and grind 'stone' materials to convert them into powder; like talcum. Is this plausible ?

Anyone accepting this challenge ... please ?


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[kahnjar1]

Hi Fernando,
Interesting piece......hope your floor supports are strong! You give weight but not size. Could this possibly be for individual domestic use, for crushing grain into flour?
Stu

[Rick]

Well, it's a floor model; that's for sure.
It's cast iron Fernando?
The Seller's explanation sounds plausible.

[fernando]

Originally Posted by kahnjar1

Hi Fernando,
Interesting piece......hope your floor supports are strong! You give weight but not size. Could this possibly be for individual domestic use, for crushing grain into flour?
Stu

No worries Stu ...
The floor is concrete and the shop downstairs is closed ... for now .
You can see by the wait that this is no domestic apparatus; you don't need such a 19 pounds beast to crush grain into flour.
But you are right, i missed the measurements:
Pestle total length 117 cms. Mortar base 26 cms.; mouth 24 cms.; height 27 cms.

[fernando]

Originally Posted by Rick

Well, it's a floor model; that's for sure.
It's cast iron Fernando?
The Seller's explanation sounds plausible.

Well Rick, i was precisely waiting for those with metallurgic knowledge to enlighten me. I can not distinguish the difference by only looking at its texture. The only 'text' i heard was that, being cast, the magnet would hardly, or not even, stick to it, which is not the case here. It all appoints to the mortar having been made with an entire interior mold and a two halves exterior one, as only the outside has a seam; and i see no signs of a possible interior seam having been ground.
Also the pestle could have been cast, judging by what it looks like a ventilating (or filler ?) sprue. But then, what seems to be a mark of a hole left for the handle introduction would have to be part of the mold., right ?
As for the "makers mark" it could also be part of the mold, like they do with cannon balls.
The handle has a texture that makes it look (to me) like it was beaten (forged) iron, though
But these are all conjectures; i am not sure of anything .


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[Helleri]

Sorry for the late reply...


So firstly, the whole magnet to test for cast iron thing is a myth. Magnets will readily attract to cast iron as they would any room temperature ferrous metal. All a magnet tells you is whether or not the item has a ferrous metal content.


Secondly, not all that is cast is cast iron. A true cast iron has a ridiculously high carbon content. There are reasons for this. Firstly they get hotter a lot easier. Whenever you have a more conductive material touching a less conductive material there is resistance (this is all pertinent but it's going to take a while to get there, bare with me). The whole wants to equalize. The resistance between one material and another builds molecular excitement that heats the more resistant material even more.


This is why some steel pots/pans are copper clad. the copper is very conductive. the steel not so much. So a little heat into the copper translates into resistance that builds a lot more heat in the steel. This works with cast iron because there is a high (higher than high carbon steel) carbon content. the carbon is less conductive than the iron. So it takes less heat to get a cast iron pan very hot, very quickly (they are fuel conservative).


A high carbon content also makes them very hard. This means they have a low friction surface (so they require less lubricant) and they resist permanent surface deformation (scratching).


These are the reasons why something like a cast iron pan is made of this iron with a ridiculously high percentage of carbon in it by weight. Because it's made for heat applications (cooking low fusible point metal casting etc).


However, cast iron is also very brittle. Hardness and toughness are not the same thing. They are mutually exclusive to some degree. You can make something harder (resistance to permanent surface deformation; Like scratches and dents). Or you can make it tougher (resistance to self separation; like chips and cracks). But generally when you make something harder you make it less tough. When you make it tougher you make it less hard.


So with this foreknowledge about how all that works in place we can now think about this logically. Would it make sense to make a pestle and mortar out of a material that is brittle and better suited for high heat applications? The obvious answer is "No". You'd want it to be made out of something softer. High/medium/low carbon steel as well as wrought/ductile iron are all better options. Now there are different grades of cast iron. So it's possible that it's just on the edge. A little higher than the highest carbon content crucible steel . But a little lower then what would be used for cooking.


So we can reason that this is obviously on iron product. But likely not the same grade of iron as the cast iron used on say a Wagner skillet. That's what can be discerned about the composition without handling the piece in person and doing some tests.


What test would I do to narrow it down? About the only reliable one. A spark test. This is fairly non-destructive (although it would leave marks). And it works basically by touching some part (obviously a part that isn't going to be visible on display) with a grinder. The spark shower, shape, spread, arc, and color can inform one as to what the composition is with high precision.


In case you are interested in knowing how to do this test yourself for narrowing down that composition (it's not hard) here is a link to a PDF on the subject: Metal Identification


Now onto application. Again we can reason this out. This is extreme overkill for pounding out some flour or meal in my estimation. You've a much harder and heavier set of materials than is any where near necessary to efficiently grind grain.


This seems more on the order of what is used to crush pigment minerals for paints and dyes. Or Borax and alum crystals for flux and fixants. Or Limestone to be baked into quicklime. Or large salts for glazing. This seems like it would fit better around a dry salter's (someone who makes inks and dyes) or a potter's setup. Even a small foundry more so than a kitchen.


Regarding construction I would say that the mortar definitely looks cast. the dot and line on it is a classic Sprue and seam mark. We even see scoured marks going against that grain. Indicating that there was left over scales/scabs which needed to be chiseled off. On either the mortar or the ball you can see the striations in the grain pattern that even indicate direction of molten flow.


The ball seems to have a large sprue mark (perhaps two?).
But on the ball there is that interesting smaller bit that looks squarish. That could very well be a pin that in part secures the ball to the shaft. So the peen at the end would keep the ball from falling off the shaft and the pin would keep it from moving up the shaft or turning on the shaft (if it is indeed a pin).


The shaft is definitely not cast. But manually hammering out a nice round round like that is fairly difficult and time consuming. Likely it was extruded and then drop forged. Which is basically where the smith has a die that the piece is suspended over. And the piece would be moved and rotated against the die as a large hammer is lifted and dropped (not driven with force but let to fall under it's own weight) onto the piece causing it to conform to the shape of the die. I wouldn't doubt it even if the rims of the mortar got a few turns against a drop forging die post-cast.


I've not seen a pestle and mortar quite like this before. I've seen ones this large and even larger. But those are invariably made of wood. I don't think this was a mass produced thing. This has the appearance of having been made in a workshop for a specific purpose.


I couldn't even begin to speculate on a date. The processes that would have gone into making this have been around in Europe at least since the middle ages. There isn't anything definitive in evident process that would nail it down precisely as to place or time of origin.


I hope what I have laid out here was not too much of a bore to read through and that it is at least somewhat helpful.

[Edit: the seam is not an indication that the mortar was made in two halves. Just that it was a two part mold for a single piece and the seam with it's sprue is simply where the mold would have been opened.closed at. Check the bottom of the mortar for another sprue mark (this will give an indication of mold orientation)].

[Edit 2: The 8 mark is likely a missed/skipped blow from a setter. That is what looks to be the exit hole of what I believe to be the pin I referred to earlier and it would have been peened there. If there were a makers mark it would likely be on the bottom of the mortar].

[fernando]

Originally Posted by Helleri

... I hope what I have laid out here was not too much of a bore to read through and that it is at least somewhat helpful...

By all means, a wealth of knowledge being poured and, as you would expect, my need of some time to digest all technicalities that you cared to pass through.
I am delighted with your explanation and thank you very much for that.
Unfortunately i don't seem to able to track its provenance: the seller has bought it in a chandelier factory (scrap lots, left overs, whatever) and that's as back as he will go.
... And no, there is no sign of seams or makers marks in the bottom; completely plain.

[Richard G]

I don't suppose we will ever know, but I would not rule out some large or commercial kitchen use, or bakery etc.
Attached, I hope, is a picture of a kitchen of an aristocratic home in the UK which seems to show a very large mortar, altho' dissimilar, to the right of the table facing you
Regards
Richard

[fernando]

Thank you for caring, Richard .
If my eyes don't deceive me, that one is even taller than mine but apparently made of wood.
Still the conviction is that mine was made to grind something harder, to work on a static & industrial basis. With its weight (73 pounds without the pestle), the kitchen personal would find rather difficult to move it aside, when needed.

[A. G. Maisey]

Thank you very much for that spark test link , Helleri. This is something I have heard mention of a couple of times, but have never used, and my own test methods are good enough for my purposes, but the complete explanation you have linked to is very interesting, and a good addition to my 'tool box'.

Again, my thanks.

[Richard G]

Fernando,
I think the mortar itself is stone, standing on a wooden column, with an iron pestle.
Best wishes
Richard

[fernando]

Oh, i see now. What brought my attention in the first place was that the column looks like having been (deliberately) turned with effects similar the table next to it; perhaps a coincidence. This pestle set however seems to be the only period implement in this kitchen, judging by the shining copperware.
Pity the pictue is not larger. Can you read what is written in that black board, Richard ?; just curious.

[Richard G]

Fernando,
This is the kitchen of Burghley House in the UK. The house and kitchen were constructed in the early 17th Cent. and has not changed a lot since. The implements are all old, early 20th Cent. at the latest. The house is still owned and occupied by the same family but is regularly open to the public

The notice, rather prosaically reads:-
"It is expressly ordered by his
Lordship that no servants shall enter
the Kitchen except on business
or remain longer than is necessary
to perform what they have to do"

Above the sign there are the heads of fourteen turtles that were apparently regularly brought live to the kitchen to be slaughtered to make soup.

Best wishes
Richard

[fernando]

Thanks much for the info, Richard.
I will keep in mind the prosaic notice and will forget about the turtles !

[Helleri]

Originally Posted by Richard G

Fernando,
This is the kitchen of Burghley House in the UK. The house and kitchen were constructed in the early 17th Cent. and has not changed a lot since. The implements are all old, early 20th Cent. at the latest. The house is still owned and occupied by the same family but is regularly open to the public

The notice, rather prosaically reads:-
"It is expressly ordered by his
Lordship that no servants shall enter
the Kitchen except on business
or remain longer than is necessary
to perform what they have to do"

Above the sign there are the heads of fourteen turtles that were apparently regularly brought live to the kitchen to be slaughtered to make soup.

Best wishes
Richard

Additions to the kitchen being 20th c. at the latest does sound about right. On the wall we can see what appear to be fully copper platters. The newest looking implements are the pot atop the cupboard and the various vessels on the table in the foreground (closest to the camera). These appear to be copper-clad-steel. The cladding of steel in copper became a thing around the turn of the last century and became popular in the early 1900's.

The idea behind it is that copper is low impedance whereas steel is high impedance. The steel insulates cold things poured into the vessel. Any amount of heat wants to migrate to an area of lower impedance (the copper cladding). So cold things poured in actually get colder.

But this works as well the other way around. Copper can be heated easier than steel because it has lower impedance. And the impedance differential creates a resistance that heats the steel even more.

So what we end up with are containers that get hotter, faster, with less fuel consumed, when placed over heat. But they also cool off quicker (internally).

So cold things stay cold longer (and get colder once poured in). Things that need to be heated get brought to temperature faster, and stand times are shorter (as they also cool down faster). The wait times in a normal kitchen operations are effectively cut in half by this innovation.

[Rick]

Fernando, you said that the fellow you got this from bought it in a defunct chandelier factory.
If they happened to make glass in that factory it could have been used to prepare the raw glass to make pate de verre or other components needed for making glass.

[fernando]

Excelent reasoning, Rick ; the best one, until further enlightening (ever) comes up.