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Preserving Bark

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  • Preserving Bark

    I am building a river table from a 110 year old basal cookie of a white spruce ( which has an great historical pedigree).

    I had no control over the season when it was cut, which can make a difference to the stability of the bark.

    After initial industrial band sawing, I was left with a roughly 2" slab of 4ft diameter.

    It still had its bark partially attached after 18 years of drying ( I think dryness is also key to success) so I wanted to keep it BEFORE I did more work on the slab.

    The wood had shrunk so I took a gusset out of the bark with a Japanese pull saw so the bark would rest tightly on the sub-bark live edge.

    I went right around the bark edge with fine brads ( 1.5"), pre-drilling the holes every two inches apart and only partially hammering them through the bark.

    Predrilling is important to stop the bark splitting and to ease the brads into the hard live edge. Always put the brads in the centre line of the bark....well away from any subsequent depth of finishing!

    I squeezed Titebond III glue into all the open cracks between the bark and the live edge on BOTH sides of the slab, using thinned down stir-stick wedges to temporarily and gently open up the cracks....I repeated the squeezing until the cracks could contain no more glue....it soaked into the bark a lot in places and I had to use a wet rag to clean any surplus drips.

    I punched the brads home. In some cases the brads would not punch home and bent....these I pulled, redriiled and used small headed black baseboard screws. Then I clamped all the cracks (not easy to do on a rounded surface) and let the glue dry for a full 24 hours. Repunching was needed when the clamping created freeplay in some brads and a couple of baseboard srews were retightend

    I router planed the slab with my homemade router planing sled (lots of fun to make from scraps and use effectively...there are some tricks to fine tune the router plunging in this setting)....allowing very loose bark to fly off if the router chipped it BUT I always ran the router INTO the bark and NOT out from the bark.

    After router planing, I soaked the entire bark and edge with Zinsser Shellac thinned 4tbs shellac to 2 tbs 99% ethanol alchohol ( bought from the Quebec liquor store...I think your store can order it if not stocked and the reason stated). NO OTHER thinner works. I made up mine a batch at a time to avoid waste, using dollar store plastic cups and wooden party coffee sticks.

    The soaking was done working from both top and bottom using a foam brush and holding a tin-foil pie plate beneath to catch and reuse the drips......make sure that you brush off all residual drips and let it dry for 12 hours.

    Then, reapply PURE shellac at full strength in the same manner....and let it dry for 24hours.

    The bark was now very stable and had darkened up considerably....quite a nice antique look. The brads did not show unless you looked really hard....you could touch-up each one with a wood colouring pen if you really wanted to!

    I belt sanded and palm sanded both surfaces of the slab smooth including the bark top and bottom faces which held up very well to this level of abuse.

    After I have done my poly-casting for the river effect, I will wet sand the surface with 2000 grit and finish including the bark with Rubio-Monocoat ( application of which is an art of its own!).

    Did you know that Shellac really is beetlejuz....I like saying that I beetlejuzed it!

    Good luck, Bryan
    Last edited by bcook; 01-22-2019, 03:35 PM.
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  • #2

    Re: Preserving Bark

    Hey, Bryan,

    Thanks for sharing our process with us. I've worked a bit with bark on a few pieces now, but never resorted to using brads or any other physical fasteners. I don't think they'll do much and may actually contribute to splitting the delicate bark. But, hey, that's only an assumption on my part, and if it works for you, then good on ya!

    I have gone the shellac route as well and agree that it certainly helps a lot. The product I use is shellac flakes and denatured alcohol; the most recent flakes were these from Lee Valley and I get my denatured alcohol from the states. (I transport it myself). Once I've allowed the shellac to dry I usually spray it with lacquer.

    I know of some who use epoxy to stabilize the bark, but haven't done so myself and therefore don't want to comment on its utility.
    All the best,

    Marty

    President of Kingston Wood Artisans https://kwoodartca.wordpress.com/

    Proud member of the Wadkin Blockhead Club

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    • #3

      Re: Preserving Bark

      Thanks Marty....predriiling for the brads stopped any splitting of this particular 2-3mm bark....I put them through thicker pieces and not in any obvious spot of potential weakness...it sure helped tighten the bark to the live-wood even with the clamps. Time and wear will tell.....I will report back in a couple of years!!!! My denatured ethanol alcohol came from Quebec. My real challenge now is how to seal both end openings where the epoxy river meets the curved bark edge of the slab, in such a fashion as to get no leaks when pouring. Best wishes, Bryan

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