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  1. #1
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    Default Jarrah - slab characteristics

    I'm preparing a 2600mm long jarrah slab to use as a desk and was wondering about some of the gum (?) pockets. I call them gum pockets because I'm not sure what they are! They aren't knots but do contain black/dark coloured, hard crystal-like "pebbles". Is this in fact gum? How are these areas typicallyp prepared/stabilised? Clean out the loose crud and fill with epoxy? In my case the main pocket is about 100mm by 50mm and maybe 5mm or more deep so a glossy epoxy fill would look a bit iffy and I'm thinking of leaving it unfilled.

    Apologies I don't have a pic to hand.

    A second question, unrelated: assuming I secure the slab to three walls on cleats, will a 2500mm span be too much for this material? The slab wanes and is 350mm wide in spots and closer to 600mm in others. It's about 40mm thick.

    Many thanks in advance as always!

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  3. #2
    Join Date
    Feb 2006
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    Perth
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    Default

    Quote Originally Posted by michhes View Post
    I'm preparing a 2600mm long jarrah slab to use as a desk and was wondering about some of the gum (?) pockets. I call them gum pockets because I'm not sure what they are! They aren't knots but do contain black/dark coloured, hard crystal-like "pebbles". Is this in fact gum? How are these areas typicallyp prepared/stabilised? Clean out the loose crud and fill with epoxy? In my case the main pocket is about 100mm by 50mm and maybe 5mm or more deep so a glossy epoxy fill would look a bit iffy and I'm thinking of leaving it unfilled.
    Yes it is gum.
    If you leave it unfilled, not only will it slowly crumble and come out over time, it will also collect fluff/lint/crud and it will be hard to get out and this will look very ordinary. I suggest filling it with black epoxy and it will look great


    A second question, unrelated: assuming I secure the slab to three walls on cleats, will a 2500mm span be too much for this material? The slab wanes and is 350mm wide in spots and closer to 600mm in others. It's about 40mm thick. !
    This depends on the load applied but in you case I reckon it will be fine.

  4. #3
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    Quote Originally Posted by BobL View Post
    Yes it is gum.
    I suggest filling it with black epoxy and it will look great

    I suggest not cleaning it out & filling it with Clear Epoxy.

    Steve
    The fact remains, that 97% of all statistics are made up, yet 87% of the population think they are real.

  5. #4
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    Default

    Well, I've taken to the live edge with a drill-mounted wire brush and a cup brush. I think all of the bark is off and I'm left with the pale sapwood.

    Looking at the photos I've posted, any thoughts as to what I've done/how to proceed? I've perhaps been a little too keen with the wire brush but also wanted to ensure all the loose stuff was off and this is the result: darker wood showing through in a few spots and few "chips" showing the same.

    Should I keen going with the aim of removing that thin strip of pale wood altogether? I should probably do a little more sanding as well to get the wire brush marks smoothed out...

    Some days I feel like a real hack, today is one them!

    IMG_1185.jpgIMG_1186.jpg

  6. #5
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    Canberra
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    Fill the gum pockets with epoxy, but use a glow in the dark pigment (blue is nice)!!!!

  7. #6
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    I dont think you have been too aggressive with the wire brush.

    If it was me, I would soften the sharp edges with some 100 grit, Fill any gum pockets etc with Epoxy, (Ive seen the glow in the dark stuff, It's not my cup of tea, but if you like that sort of thing, it's an idea). Then I would give it all a good sand & seal it with polly.

    Be sure to give the underside the same amount of coats you give the topside.


    Steve
    The fact remains, that 97% of all statistics are made up, yet 87% of the population think they are real.

  8. #7
    Join Date
    Nov 2010
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    Perth W.A
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    There are a few good ways of dealing with voids, black epoxy resin works well but can be expensive.
    I often use Builders bog turbo mixed with the concrete colouring oxides they can be mixed togther to give almost any colour, small defects can be filled so that they are almost invisible especially in jarrah and darker timbers.
    Larger voids and defects can look less than convincing but you can use black oxide to make them look like gum veins.
    Be sure to mix in the oxides first and make sure you are happy with the colour before adding the hardener as it will harden in a few minutes.It sands beautifully when fully hard.

    The builders bog turbo has a hardener that is red in colour which can be a pain with very light timbers as it changes the colour of your mix very slightly, the mix ratio is about 50:1.
    There is another brand that has a white hardener, can't think of the brand at the moment, might be Selley's ?

    You can also use west sytems for a clear effect, some people put coins, pebbles and even small opals in the voids and then clear fill them.Don't fill very large voids in one go as there is significantt heat build up and some out gassing resulting in trapped bubles.

  9. #8
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    Jul 2008
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    Default gum pockets

    My favored way of dealing with gum veins-pockets is to fill with clear casting resin-slightly tinted to match the timber-also with some of the crumbled solidified gum-from off-cuts etc.so that it looks like solidified gum. Can be made to have the same finish as the rest of the surface.-Very effective-if the tint is right. By the way use spirit type stains -not pigment-& definitely NOT water based. When it works well-looks totally natural with a smooth surface.

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