stos
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imitation tortoise shell!
Hello!
I remember somebody was looking for this!
https://www.dictum.com/en/materials/hybrid-materials-acrylic/831450/...
hope it helps!
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Brian Prunka
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This says it is made from casein, which is a plastic derived from milk. While excellent at mimicking the visual appearance of other natural
materials, it tends to be brittle, and likely lacks the strength of actual tortoiseshell. So it would work as a pickguard if you want that look, but
is probably not suitable for a plectrum (risha/mizrap).
Casein is often used to make buttons, as it can look nearly indistinguishable from traditional bone/horn buttons.
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Jody Stecher
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I have played with a risha made from casein. Two of them actually. It's true that the material is brittle and prone to cracking. But a well fashioned
casein risha does not produce a brittle sound. The sound is musical and supple.
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oudistcamp
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Casein picks
I use predominantly casein picks for oud playing.
I find them more resistant to breakage than horn picks, but not as resistant as the real stuff.
Casein picks have a really good 'boing factor', and come pretty close to the real thing.
The sheets are about 3-4mm thick. You would need to carefully split the thickness in half with a small table saw (Proxxon).
Then thin the pick down with a sharp cabinet scraper. Finish with fine grit sandpaper (120-800grit).
Keep testing the risha as you play, and touch it up with more scraping and sanding as needed.
The photos show all but one, are casein picks. Can you spot the real one?
The tapes and gold marker dots are to allow for easy retrieval after I drop them.....
[file]35355[/file] [file]35357[/file]
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jdowning
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Casein glue made from milk or cheese has been used for woodworking since the ancient Egyptians. Presumable these imitation tortoiseshell panels are
just made from a casein glue formulation spread out to dry in a thin sheet with coloured pigments mixed in to imitate the real shell grain and colour?
The glue can be purchased ready made as a dry powder for mixing with water or can easily be home made from fat free milk. Sounds like an experimental
project in the making!
Dried casein glue is so hard that it tends to blunt tool cutting edges.
An interesting application other than rishas might be as a finger board material. German lutes in the 18th C sometimes used tortoiseshell backed with
gold leaf to make dramatic looking fingerboards (the shell material being translucent allowing the gold to shine through).
The imitation material might just work as well as the real stuff being hard and translucent? Brittleness would not be a disadvantage for a fingerboard
material. Would look just as good on an oud I imagine.
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Brian Prunka
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Very interesting John! I love your experiments.
I would expect that it has a nice sound, as it is a natural protein similar to what would be found in real tortoiseshell. It is my understanding that
as plastics go, it is a fairly brittle material, not that it produces a brittle sound.
Oudistcamp, Interesting that you have found them not too prone to breakage, that is good to know. The "brittle" description is probably relative to
other plastics (celluloid, acetal, nylon, etc.), rather than other natural materials (horn, tortoiseshell). Am I correct in understanding that you
cut them in half from the thickness you receive? That seems like a tricky prospect, though I suppose with the proper equipment anything is possible.
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elreyrico
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is there a way to make the material softer ? using a plasticizer to make less brittle ? vegetable oil ?
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oudistcamp
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Yes, Brian. I first saw them into 1cm wide sticks, then use the Proxxon table saw and split the thickness in half.
That way, I get double the amount of picks and much less casein to scrape/sand off.
Yes, you have to be very careful when splitting - use wooden guide sticks and be fully aware where the blade extends.
No music, no talking, no long sleeves, no rings and watches, no chewing gum. Just the usual precautions.
One can also just thin the 4mm thickness by passing the sticks through the drum sander, or by scraping.
Its all fun and good.....
I have broken a few horn picks while playing the oud, but I have not broken any casein picks.
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Brian Prunka
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Cursory research indicates that there are various chemical processes potentially available, some likely result in a more flexible result.
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jdowning
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Casein can be plasticised to the point where it is like rubber. Natural plasticisers like honey and vegetable oils can be used. In fact there is no
need to use any synthetic (or dangerous chemicals like formaldehyde) products to make casein.
Clear (transparent?) casein is made by mixing in Borax (another natural product) to make Borax-Casein. This type of casein is also compatible with
coloured pigments and keeps well unaffected by bacterial decay. This would be my first choice as a starting point for any experimental work in making
imitation tortoiseshell sheet.
Apparently the commercially available casein glues in powder form have solids added to give them a tan colour and therefore may not be translucent. So
best make your own casein glue if clarity is an objective.
Artificial ivory is made by mixing bone dust with casein. Sheets of
this might be used (with wooden underlay) for rosettes or for inlay decoration. Metal powders might also be combined with casein to give an
interesting metallic effect? To avoid blunting of edge tools inlay shapes or even rosette patterns might be cut out of the freshly prepared casein
sheet before it has fully dried and hardened using either a knife or mini 'cookie cutters'?
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Brian Prunka
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Fascinating, John. Can you point to any resources of information on the appropriate process you would use to make these materials? I tried to do some
searching but it was confusing, with most of the available materials more suitable for making actual glue as opposed to plastic, and a lot of
conflicting information.
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jdowning
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There are a number of formulations of casein with different properties but I suspect that there is no essential difference between casein the glue and
casein the mould-able plastic one is just thicker than the other in the fluid state.
Here are some older technical papers dealing with casein that may be of interest:
https://ia600504.us.archive.org/2/items/caseinitsprepara00scherich/c...
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn158.pdf
As making casein is a low cost, safe process using food grade and household materials readily available from local stores, I plan to do some
experimentation in making borax-casein glue sheets - just out of curiosity.
Will report my experiences later on this forum.
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jdowning
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As I shop around locally for the materials to make casein products I have looked at what YouTube may have to offer in preparing these products at
home. Here is one of a series of excellent instructional videos by chemist Robert Murray-Smith (based upon the book previously posted it so
happens).
https://www.youtube.com/watch?v=BnXGZKCrktE
As a chemist, Robert's instructions are more informed than some - for example on how to purify the casein made from skimmed milk powder - so will be a
good starting point for experimentation.
His spoken accent is Northern English so may be a bit difficult for everyone to follow.
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