How Do I Prepare Bone?

Discussion in 'Luthier's Corner' started by Pjam, Jan 19, 2011.

  1. Pjam

    Pjam Senior Member

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    Sorry if it's been covered before, but what should I do? just go to the butcher and ask for a bit of a cow and wait for it to dry out?
    Is it as simple as that? or am I looking at the wrong species?

    I'm not that clever at getting a good nut first try, I've got time to practice but not an endless supply of bone!
     
  2. delander

    delander Senior Member

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    1. Clean the bone thoroughly (boil if necessary).
    2. Bury in a pail of warm, clean, dry sand for a month or two.
    3. Keep pail of sand & bone warm whilst drying.
     
  3. gator payne

    gator payne Senior Member

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    Go to a pet smart or other pet store and buy a large femer bone. boil it to remove the oils, meral and other by products, allow it do dry out a few days. saw it into a blank sand into a level blank on three sides and ther you go.

    better yet spend a few more dollars and by camel bone blanks ready to final shape. It is in my opinion not worth the effort to process new raw bone compared to the cost of pre prcessed and planed blanks from a lutherie supply house. bare in mind that you will on ocasion get a blank with a flaw but a typical cow bone preprepaired blanks will cost around $5 ready to be shapped. A camel blank around $10 and are a bit harder to find but availble. Really processing you own blanks only makes ecanomical sence if you are doing several JMO
     
  4. oigun

    oigun Senior Member

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    First clean the bone's soft tissue for as far as it goes, then cook it for an hour or so in water with ammonia. Slice it up in convienient pieces using a hacksaw. Let it dry for a couple of days and emerge it in benzene for one or two weeks till the the benzene (washing/white gasoline??) stays clear (the smaller the pieces the less time it takes). You want all the grease to dissolve because that affect the quality of your nut and affect your wood, laquer and glue.
     
  5. bertzie

    bertzie Senior Member

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    Use ultra-fine sawdust, (like the kind you get from sanding). Especially if it's porous wood. It'll absorb the moisture better than most any other material.
     
  6. Freddy G

    Freddy G V.I.P. Member

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    I have on occasion walked out into the yard and stolen one of my dog's bones (she didn't like that very much):D

    I found that it was already sun bleached white, dry (well maybe some slobber) and hard. Cut it up on the bandsaw, and there ya go!
    As was mentioned, make sure it's a femur, not only for it's size but also because it's a weight bearing bone from a large heavy animal and that means the bone is dense.
    Like gator payne says though, it's not really that economical compared to buying bone blanks. And your dog will thank you.
     
  7. Pjam

    Pjam Senior Member

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    Thanks guys. For someone who's learning it's great to have you around.
     
  8. AnthemBassMan

    AnthemBassMan Senior Member

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    -What I did when I made my own bone saddle from fresh cow bone was boil it in soap water for about 2 hours. Keep the water at a simmer, not a rolling boil. Then I filled a glass jar with Coleman lantern fuel, capped it and let it sit in there for about 3 weeks. The Coleman fuel leaches out the fats that are still inside the bone. You could see a bit of sediment at the bottom of the jar. Here's a copy of the article I kept when I did mine.

    Note: the following is a long discussion of and instruction for bone
    cleaning and preparation, not exactly graphic, but nonetheless specific.

    It's easy but involved to prepare bone really REALLY properly for
    instrument work--I found that my experience as a vertebrate museum
    curator/preparator at UC was invaluable in this regard because it taught
    me how to prepare bone really well, and how short-lived some crafts
    processes really are (museum material is prepared so that it will survive
    for centuries). The main problem in lutherie is producing material that
    will do the job, last a long time, and not damage the instrument it was
    meant to enhance. That means that the bone must be very clean and
    grease-free and therefore stable and harmless to nearby materials.
    Cleaning and degreasing are conceptually and technically easy, but natural
    materials being what they are, it's sometimes too easy to lose patience
    with the preparative process and accept "almost-right" material. Don't.

    Source material is pretty easy--the best place to look is a grocery store.
    Buy a fresh cow "knuckle" or a section of long bone, (commonly
    sold for soup, often not on display but almost always available). You can
    also use other species and bones, but cow bone has the virtues of density,
    size, and limited (sometimes nonexistent) marrow cavity. Ask the butcher
    to saw the knobby ends from the bone, or do it yourself with a bandsaw or
    hacksaw. Extract as much soft tissue as possible from the exposed marrow
    cavity (straightened wire coat hanger and compressed air is a wonderful
    combination), then immerse the bone in water or water with household
    ammonia or a little mild detergent added. The ammonia method cleans best
    and fastest but requires a stove with an efficient exhaust hood, the
    detergent is not too far behind (Ivory liquid or similar), and pure water
    works well but takes longer. The advantage of pure water is that the
    resulting broth is soup. Bring the liquid to a boil, then reduce heat and
    simmer for 30-40 minutes (ammonia in water), 50-90 minutes (detergent in
    water), or up to two hours (pure water). The object is to cook away the
    soft tissue and begin the degreasing process. After the assigned time,
    remove and cool the bone, then use running water in combination with
    fingernails and a stiff brush to remove the remaining soft tissue--don't
    be afraid to return to the simmer pot.

    After the bone is cleaned of soft tissue, air-dry for a day or so, then
    cut with a bandsaw or hacksaw to oversize blanks (bridge, nut, saddles,
    etc). Air-dry the blanks for at least 2-3 days, perhaps a week during
    humid times--to degrease properly they really have to be bone-dry, so to
    speak..... Degreasing is the most overlooked and under-done step in bone
    preparation, even in a few museum preps. Greasy bone will leach fat
    slowly but forever, and the grease will contaminate glue joints, make
    finish and wood part company, stain and degrade wood, and itself
    eventually destroy the bone through a process of slow combustion (one
    carbon at a time). I once attempted to repair a Martin D28 with a homemade
    bone saddle that had leached grease right through the ebony, so that it
    had seeped into the top, caused the bridge AND BRIDGE PLATE to loosen, and
    was almost impossible to remove completely so that a new bridge and bridge
    plate could be installed. I still have nightmares.... Trouble is, bone
    can look clean yet have a substantial grease content that won't manifest
    itself for years, but by then some of the damage will be much too advanced
    to fix. If I've made you paranoid about bone grease and convinced you to
    avoid using bone that even has the hint of a tiny possibility that there
    might be a microliter of grease somewhere in it, good.

    To degrease bone, immerse the very dry blanks in about ten volumes of
    white gas for 1-3 _weeks_. White gas, AKA Coleman fuel, is really
    flammable and so this step should be done in a glass container outdoors
    somewhere in the shade far from structures. Really greasy bone will
    discolor the white gas after just a day or two so replace it at that time.
    The safest disposal for small amounts of white gas is probably to allow it
    to dissipate into the atmosphere, but if you decide to go into production
    and generate lots of waste white gas, best make prior arrangements for its
    legal disposal. BTW, museum preparators use much more toxic solvents, such
    as carbon tetrachloride (CCl4), but only under extremely carefully
    controlled conditions that are simply not available out in the real world.
    Improperly vented CCl4 will eat your liver and cause you to die very
    prematurely, to put it bluntly, so that's why I recommend white gas (which
    is bad enough).

    After the requisite degrease time (which can and should be extended if the
    bone shows any sign of residual grease, such as translucent spots), remove
    the bone blanks from the gasoline, rinse once in clean gas, and air-dry.
    Degreased bone should dry really fast, like in much less than an hour--if
    it doesn't, there is residual grease in the bone so put it back in a new
    gasoline bath. Again, I can't over-emphasize the importance of thorough
    degreasing--you could badly damage someone's valuable instrument if you
    use greasy bone.

    Next, shape and final-fit (but don't install yet) the bone item--nut,
    saddle, etc, and polish it with fine compound (tripoli, then rouge, after
    smoothing with a file and wet-or-dry sandpaper. If the bone is not white
    enough (an individual preference--it will be pretty white after
    degreasing, but not glistening white), bleach with hydrogen peroxide. I
    use 3% peroxide, the garden variety drugstore purported antiseptic, and
    immerse the bone for about ten minutes. Longer tends to overwhiten and
    make the bone look flat. Air-dry and glue in place. DO NOT USE HOUSEHOLD
    BLEACH FOR THIS OPERATION!!. It won't bleach, and it seeps into bone and
    comes back later to haunt you--it makes the bone friable, but usually not
    for several years. Museum people generally avoid bleach, because though
    in years past it was sometimes used for skeletal preparations, most such
    specimens have long since literally crumbled to dust. Nowadays museum
    people almost universally use ammonia (at household strength) for chemical
    cleaning of skeletal material. Bleach is potentially useful during the
    cleaning process, but ammonia is so much safer for the bone and just as
    effective for cleaning that the choice is clear. Ammonia also begins the
    degreasing process (as does detergent), which bleach won't. Also,never mix
    household bleach and household or any other kind of primary ammonia
    (NH4OH.H2O), because your final memory will be of the pretty green but
    acrid chlorine gas that emanates and causes pulmonary edema.

    I realize this was much more than most want to know about where bone comes
    from, but like any preparative process for natural materials (wood
    seasoning, etc), the bone-cleaning process is involved* and best done
    properly start to finish if you want your nut/saddle/bridge to look nice,
    work well, and last longest.

    Sean Barry

    *Also, if the above seems very involved and tedious, it's because it is,
    and that's why for most of my work I purchase bone and saddle blanks from
    the various lutherie suppliers. These are imported from Japan, and are
    marvelously clean, grease-free, and inexpensive. The above instruction is
    really necessary only for unusually large bone pieces, which this post
    addressed."


    L8R,
    Matt
     
  9. Pjam

    Pjam Senior Member

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    Thanks Matt :)

    Just one question, what is Colmans lantern fuel? We've got differnt trade names in the UK.

    Parafin perhaps?
     
  10. David Collins

    David Collins Senior Member

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    White gas. You can also use kerosene, naphtha, mineral spirits - they're all just different grades of petroleum distillates, and do a fine job in helping to degrease bone.

    I get a number of femurs from local butchers and farms each year, then typically cut off the knuckles to expose the marrow and bury them in the back yard for a few months. When I dig them up toward the end of summer, most of the work is already done for me.

    I've scraped off the soft tissue and boiled them straight from the butcher before, but it seems that boiling with so much fat and tissue present tends to drive oils further in to the bone as much as it takes it off the surface. By burying them to get rid of all the soft tissue first, it seems to take fewer boiling sessions to clean them up (replacing the water until it starts to boil more clear, have less oils coming out). I still cut them up and soak them in white gas to dissolve out as much remaining oils as possible, but I'd say bugs and bacteria in the dirt do most of the work for me.

    If you're making just a few nuts or saddles then buying processed blanks from suppliers can be much more practical. For me, I use a lot of bone, and need pieces in such a never ending array of shapes and sizes that this is simply the most practical supply I've found. Plus I prefer to have more control over the quality and processing of the bone. Many of the blanks that I've bought in bulk are mediocre in quality at best - warped, porous, chalky from harsh chemical treatments, etc. When I buy and process the bone myself I know it's coming from a pastured cow that developed strong thick walled bones, rather than some 15 year old dairy cow with osteoporosis that never left a pen somewhere in China, then processed with harsh chemicals that may degrade the bone.

    Okay, maybe imported bone blanks aren't that bad (blanks from places like StewMac are usually just fine), but I've found it the most economical and practical source when you need a large variety of shapes and sizes of good quality bone. If you only need a few and you know exactly what sizes you'll need, then it's probably easiest just to order a few blanks from StewMac.
     
  11. Thumpalumpacus

    Thumpalumpacus Senior Member

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    It's kerosene, so far as I know, which is paraffin:

    Kerosene - Wikipedia, the free encyclopedia
     
  12. Jim_D

    Jim_D Member

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    How about the handle from an old knife or fork? I bet you could get a set of those at a charity shop or car boot sale for a good price. Reminds me of reading about using a toothbrush handle to practice cutting out a plastic nut. My brother once spent a day filing a door bolt down square to make a brass nut too.
     
  13. David Collins

    David Collins Senior Member

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    It's easy to forget how different the terminology is applied in different countries. In the US paraffin is what we call canning wax.
     
  14. gator payne

    gator payne Senior Member

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    That is exactly what I was fixing to say:applause:
     
  15. Pensioner

    Pensioner Member

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    Using fresh cut bones is a hassle. I bought a large, thick walled one from the local pet store. It had been cleaned up (boiled?) before being packed with whatever that "treat" stuff is that they use. I cleaned the muck out, gave that to the cat (refused to touch it) and boiled it for about ten minutes. Then through the dish washer a couple of times and, after drying out a week, I started sawing with a hand saw.

    That was the hard bit. Bone, as you know, is hard stuff. If you've got a band saw then your in good shape. I reckon it took me an hour of sawing just to get a good enough blank for a nut. You have to ask yourself how much your time is worth. Buy one and forgo all the boiling washing and sawing.

    On the other hand, if you don't quite get the bought one right you've got to buy another. With a prepped dog-treat-bone, however, you might be able to get a dozen or so blanks.

    Also, the smell of sawed and filed bone takes a little getting used to.

    P
     

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  16. AnthemBassMan

    AnthemBassMan Senior Member

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    -Oh man! You can't say enough there! I ran mine through my Dad's thickness sander to get it roughed down to what I needed for my saddle. We both had our shirts over our noses. Here's a couple links to the saddle I made. Not quite step by step, more like a work in progress. I did this probably 4 years ago. I work in a grocery store so I went to the meat dept. and ran a couple soup bone shanks through the bandsaw to get some nice pieces to use.

    New Saddle pictures by AnthemBassMan - Photobucket

    New Saddle Part 2 pictures by AnthemBassMan - Photobucket

    L8R,
    Matt
     
  17. David Collins

    David Collins Senior Member

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    Agreed. It's simple for me - the time it takes me to cut up a couple of bones in to useable blanks then size them as needed on a belt sander is less time than it would take me to put together an order for blanks. That's because I'm tooled up to do it all very efficiently and easily. If I didn't have the tools to make this so simple, I certainly wouldn't bother trying to process your own.
     
  18. Pjam

    Pjam Senior Member

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    Jim THAT is clever :applause: I'll try it. Even the size is about right, not to much cutting perhaps.
     

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