Methods of Core Preservation

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Methods of Core Preservation

• Phil Rumford Superintendent, Gulf Coast
  Repository
• Meeting of the Curators of Marine and Lacustrine
  Geological Samples
• Estes Park, Colorado. September 2007

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A Simple Method

• Polyethylene Bag
• Oxygen Absorbing Pack
• Bag Sealer
• Advantages
• Cheap
• Packs can absorb up to 200cc of O2
• Retards mold, mildew, and bacterial growth
• Disadvantages
• Methods success relies on barrier qualities of
  bag
• Messy, labor intensive, difficult to store

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More Sophisticated

• Use an aluminized bag as an effective O2 barrier
• Flush bag with N2, add O2 pack, and core section
• Heat seal bag

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Problems

• Expensive
• Time consuming
• Difficult to know when bag is properly flushed
  with N2
• Requires skilled/patient user
• Tried on ODP Leg 169 on sulfide rich cores, and
  was not successful

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Vacuum Sealing

• No Aluminized bags
• No N2 flushing or O2 packs
• Simply vacuum seal the corewith a good barrier
  film
• Small table top models (as shown)cost _at_ 2.5K
• Works great on hard rock samples with very little
  moisture content
• Negates the need for d-tubes, increasing
  available storage area

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Problems

• Nozzle type sealers will not give an adequate
  seal on wet sediment cores.
• The prolonged exposure to vacuum that is
  necessary on sediment cores may desiccate
  material and ruin delicate structures
• Use of this method on the RV Chikyu was not
  successful

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Possible Solution

• Food industry useschamber vacuum sealers to
  vacuum seal wet goods
• Chamber sealers are expensive and not
  commercially available in the size needed for
  cores
• May still have the problems of desiccation and
  physical damage to the cores

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Shrink Film

• Benefits
• Has no effect on sample
• Excellent barrier films available cheaply
• Equipment readily available - cheap and reliable
• Equipment easily tailored to fit budget and
  work-load
• Negates the need for d-tubes, increasing
  available storage area
• Allows clear view of core after wrapping

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Types of Equipment Available

• Basic systems available for under 200

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Manual L-Bar Sealers Cost used 2-5K
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• 3

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Automatic Side Seal WrapperCost 30-70K
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• The side seal wheel is shown below
• It seals the long axis of the bi-fold film

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• The bar sealer seals and cuts the leading and
  trailing edges of the film.
• It is operated by a photocell that can detect the
  presence of the core liner.

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The in-feed conveyor and film feed mechanism
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Tashina feeds a core section into the machine
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The core section being wrapped
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The core section enters the heat tunnel
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The wrapped section
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D-tube storage racks at the GCR
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Wrapped cores without d-tubes in close packed
storage
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Type of film used by IODP

• Cryovac BDF20001
• Good O2 and water vapor barrier
• Easy to use, will shrink and re-shrink
• Gives a clean clear finish
• Costs about 0.12 per 1.5m section to wrap

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Future of Plastic Film

• Rapidly evolving technical field (nanotechnology
  in plastics)
• Driven by pharmaceutical and food industries
• New types of film constantly being produced

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New O2 Scavenging Film from Cryovac

• The scavenging component of OS films is an
  invisible layer of the packaging. A patented UV
  light triggering process starts the scavenging to
  remove residual oxygen up to 10 - 20 faster than
  ever before.
• With faster scavenging, your products will retain
  their high quality longer by slowing oxidative
  deterioration of efficacy, integrity,
  reliability, potency and freshness.