I moved into a new home and found a ton of leftover cedar plank siding in the attic that I want to use to construct raised beds. However, they are tapered in shape so I would like to put two planks together using wood glue for added strength. Over time, will wood glue leach into the soil and if so, would it be problematic?
I think that would depend on which wood glue you choose.
The tight bond products would probably be a good choice since they do make one that is water proof and they all are based on the "Elmer's carpenter's glue recipe" which is also a fair choice even though I don't think they make a waterproof or resistant model.
I would not use any of the "polimer" glues like gorilla glue, those are more likely to have components that might possibly leach since they are a resin type expanding glue.
This is probably an either or proposition in the larger picture, but I personally like to be overly cautious when it comes to things like glue or treated wood.
Bryant RedHawk wrote: they all are based on the "Elmer's carpenter's glue recipe"
Classic white or yellow wood-workers glue (Elmer's) used to be made from cow hooves and other connective tissues from horses and cows. They even had a cow integrated into their logo; Elmer the bull, mate of Bordon's Elsie the cow. Today, wood glue is made of synthetic ingredients, but perhaps you could find someone who still manufactures wood glue using the classic cow-hoof formula (hydrolyzed keratin). That would be benign for your soil. Jello is pretty much made of the same stuff—if you would not be concerned with dumping a dish full of lime jello into your compost pile, you wouldn't need to be concerned about using classic animal-based glues.
But does anyone sell that stuff anymore? A quick search of the interwebs turned up nothing for me. And I'm not too sure how long it would hold up in a consistently wet environment like a raised bed.
I'd use mechanical means to hold those boards together: nails or metal screws. If they rust, that's not a problem—it just adds to the iron in your soil and your plants will appreciate that. Or use stainless screws that will not rust if you want them to last forever. Or wood pegs? Is there a way to connect those boards using cedar pegs? Its not like they have to bear a lot of weight or anything --- they just have to sit there on the ground and keep the soil in place.
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Timothy Markus wrote:Freddie, do you mean that the boards have a wedge-shaped profile and you want to invert one so that the thin edge is reinforced by the thick edge of another? Like putting these together: AV
Yes, exactly as you described. I feel that mechanical attachments might be overkill for these boards since the thing edge is actually very thin. Putting them together will get me about a 1/2" thickness.
I would just double them up, staggered at the joints if you want, pound pegs around the perimeter, put in the boards, then infill the raised bed. The soil will push the boards into the pegs, so you don't need to glue or fasten them at all.
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