Following the iron brush

Hello to all,

We have had some discussion about mother of pearl here at Following the Iron Brush.

viewtopic.php?f=55&t=368
http://www.followingtheironbrush.org/vi ... =55&t=1428

The softening, slicing and bending of MoP is a recurrent theme in the field of lacquer craft.

I have re-read the threads about them, and mined that copy of mine of “The Inro Handbook” from the chest. The text mentions the softening and bending of MoP more than one time.



The book “Masterpieces of Chinese Lacquer” also mentions pearl inlay, and the softening of MoP.

Oh, those silly writers of science books…

Have a nice day!

János

Janos sorry for my very late reply, but I had never seen that topic before!

viewtopic.php?f=55&t=1428

Thats really interesting, Janos.
Did you gave this a trial?

I am actually mistrusting books wich are not written by craftsmen or artists in their particular fields.

Sometimes an art scientist or a collector might to read something into something he has seen (the use of some acid) or heard (from a friend of a friend) which could be quite different in fact. But who knows....

One thing I'm wondering is do you think the thin sheets of MOP are created by a) splitting layers off the shell, b) slicing thin layers with some type of veneer saw, or c) by grinding down a relatively thick piece until it is <0,5mm thick? Since shell is a laminate structure splitting is possible (we've all seen it happen on a small scale using a jeweler's saw), but I can't understand how such large pieces can be split without breakage?

the use of acetic acid is described as well in the book Urushi No Waza.

I have no means to scan the pertinent section of it but if photos will do I can snap some and post them at some point.

Hello to all,

Yes, Karl, I have done some experiments. At first I simply soaked MoP plates (white, 1,2~1,4 mm thick material I use for inlays on furniture) in clean water for 24 hours. Nothing happened. Then soaked MoP in vinegar (10% acetic acid) for about eight hours. The acid attacked the sell and dissolved its surface, so the starting thickness of 1,2 millimetre was reduced to 0,8. I was not really surprised, as jewelers use etching on MoP to create patterns (by using nitric acid in place of vinegar for the sake of speed). Then I boiled MoP for about six hours. I tested the hardness with a knife, and the material was a little softer, but only for a short time (15 minutes, or so).

Dear Doug, on Chinese lacquerware I have seen the MoP was about 0,5 mm thick/thin so perhaps it was made by grinding down to thickness. But on Japanese pieces the shell is only 0,1 millimetres thick at times. Grinding down MoP uniformly to such a small thickness would be hard job, and a wasting of precious material. Until the end of the XIXth century MoP was “fished out” by free divers (women in Japan) in small quantities… and larger sizes and exotic colors are very expensive even today.

Splitting/slicing with a knife blade seems to be the most plausible solution to me, because modern lapidary cutting equipment or even the fine jeweler’s saw blades were unavailable to the XVIIIth century Japanese craftsman. But slicing requires the softening of the MoP to avoid breaking and checking, just like in the manufacture of knife cut wood veneers.

Mother of pearl has a layered/laminated structure: thin (under 0,1 millimetre) aragonite layers are bound with animal protein, just like a layer cake. The question is: how to soften this protein adhesive temporarily, as a softened state would allow the flexing of the structure.

Have a nice day!

János

So are we are working towards the assumption that we need to weaken or dissolve the organic protein that holds the calcium carbonate, the argonite platelets together ??.. Has anybody tried boiling the MOP in acetic acid?

And I found this.. think it might be worth while exploring precisely the structure of MOP.

"The Growth Of A Shell
Nacre provides shelter for the soft-bodied mollusk; the strength and resiliency of shell enables the animal to survive the unceasing environmental and tensile pressures endured in its habitat. The shell structure begins with an oval-like, rounded shape called the umbo. The umbo is gradually surrounded by concentric growth rings of nacre that will thicken and widen outward continually, to accommodate the animal throughout its lifespan.

The Shell Structure
The mollusk’s shell contains three layers: the periostacum (the conchiolin layer), the ostracum (the prismatic layer), and the hypostracum (the final mother of pearl layer).

The Protective Outer Shell
The periostracum is the outer layer of the shell; this is the first layer to form around the mollusk during its immature, glochidaeal stage, and is composed entirely of organic conchiolin, the dark brownish, black, green or dark blue-colored organic substance made up of keratin proteins which are also be found in the human epidermis.

The Prismatic Layer
The ostracum, or prismatic layer, is the central layer and is composed of tiny hexagonal calcite crystals measuring one micron in size. In freshwater mollusks the crystals are mainly aragonite, due to variations of trace elements found in the water. Contrary to its name, the prismatic layer is neither iridescent nor beautiful; it provides a level of stability to the hypostracum, and is brown to brownish-yellow in color with a porcelain finish. The crystals are arranged parallel to each other and are held together by a thin film of organic material.

The Nacreous Layer
The hypostracum, or mother of pearl layer, is the final layer that displays color and iridescence. Mother of pearl is almost entirely made up of calcium carbonate (CaCo3), which contains millions of crystal aragonite platelets. These crystals measure 0.3-0.5 microns in diameter, and are stacked on top of each other in a brick-like structure. Interspersed lie extremely thin sheets of conchiolin that “glue” the platelets together. Each layer grows intermittently; some layers show straight and even growth, while others are rounded, however none of them run directly parallel to the surface of the shell. The result is similar to topographical maps detailing ridges and valleys when viewed under 40x magnification.

Growth of the mother of pearl layers is very slow. In P. margaritifera, the average rate is approximately 13 aragonite platelets per day; other species secrete nacre at faster or slower speeds depending upon environmental conditions.

The Crystalline Effect
Aragonite platelets are transparent and mimic wavelengths of visible light, enabling light rays to be absorbed, scattered and reflected back at the viewer in various hues resulting in the phenomenon of iridescence. The word iridescence comes from the Greek word iris, and translates as “Rainbow”. Grecian legend portrays the ancient goddess Iris personified as a shining arc of color announcing divine proclamations from Olympus to mortals who revered her as a spiritual advisor. "

Hello to all,

After reading Clive’s post (scintillae, scintillae...) I have made a quick search on the web, and a new experiment. Alkaline solutions do not dissolve calcium carbonate, but attack proteins (not as effectively as acids, but…) So I decided to try out ammonia, and placed a piece of MoP into a 30% technical grade solution of ammonia. After about 25~30 minutes I tried the hardness with a knife and the MoP seemed much softer to me. Unfortunately, my workshop is located in a basement in a street, and has inadequate ventilation, so I could not let the MoP soaking overnight. Her is anybody out there with a garden shed wanting to conduct an experiment? I would be grateful.

Have a nice day!

János

Great minds think alike Janos.. I too started to think about a strong alkaline solution to attack the protein that hold the sheets of aragonite (calcium carbonate) together.. anyway I read somewhere that Lye (Sodium Hydroxide) might do such a thing and have placed some MOP in a hot solution to soak overnight.. I'll do a strong ammonia solution (I have a garage ) as you request as well.

OK.. done Janos.. my ammonia solution is about 25%.. will check it in the morning.

Morning... Its a good morning as had a terrific result at the poker tables last night but unfortunately cannot report any breakthrough on the MOP front. Janos.. I left a piece in the ammonia solution for 14 hours with absolutely zero effect. The experiment with Sodium Hydroxide was equally dissappointing.

Back to the drawing board.

Dear Clive,

Thank you for doing the experiments! So you have not find any change in the properties of the MoP… damn. But the solution must be simple: those ancient Japanese men did not have refined technology to employ… but they succeeded, somehow… Really frustrating, isn’t it?

Any idea, any new method to try?

Have a nice day!

János

my bet would be on some simple protein dissolving enzyme .

Hello to all,

Dear Ford, that enzyme thing is plausible, but how could I attain proteinase enzymes easily? Perhaps I should try and put some MoP in a bottle of Pepsi.

I have found a little more about shells in "Conservation of Furniture".



Have a nice day!

János

you could try health food shops....