wilson32
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The truth about plywood sawdust ?

Hi - I just purchased a Jora JK125 and I would like to use sawdust to keep the moisture down. My saw dust source is mostly from solid pine but there is a small percentage of dust from plywood. There seems to be a lot of anecdotal "don't compost plywood dust" which makes sense because it is intuitive and easy to repeat.

Upon searching I have found info that suggests there really is no problem composting the glues found in plywood - although I have yet to find an explanation of what the glues are and what if any toxins the dried glue may transfer to my vegetables.

Is there a scientific truth on this topic? If it matters, the plywood that I usually cut is interior grade baltic birch.

Thanks for your thoughts.

toxcrusadr
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I have never been too concerned with the kind of glue used in plywood and chipboard. Having said that, I also have to admit I don't know much about its actual contents, and as an environmental chemist and composter I probably should look into it. One thing about glues, though, is that once they're dry, they're a lot like polymers or plastics. Large molecules have much less chance of being toxic. Some glues have solvents which can be more toxic, but wood glues tend to be water based rather than solvent based, and besides, any volatiles will evaporate away during the drying process. Water based glues do their gluing with long chain proteins or carbohydrates, and I would think they're fairly biodegradable. It wouldn't surprise me if plywood glue was made from waste tree resin, but I don't know that for sure.

You certainly want to avoid sawdust from treated plywood (formerly CCA and now something else, the initials escape me) and lumber.

toxcrusadr
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After some quick reading it appears urea formaldehyde glue was the target of some new regulations back around 2006. Formaldehyde of course is a toxin, but due to its volatility and biodegradability, I'd be much less worried about it in the compost than I would if I were surrounded by offgassing products inside my house. Even if it were still there, and I suspect it's been greatly reduce or eliminated in recent years.

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applestar
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Yep I was going to say formaldehyde too. The thing is, the long chain carbos -- as well as the moisture in the wood and cellulose -- would require *some kind* of preservative. Formaldehyde.... Or something else if there are less of it in use now.

What do preservatives do if not kill/prevent microorganisms from growing?

So I'm still wondering about how plywood/pressboard/particleboard sawdust might affect the compost pile.... :?

toxcrusadr
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Not sure what you mean about preservatives, unless you are referring to treated lumber. Regular untreated OSB and plywood for interior use does not have any special preservatives. The formaldehyde is only there as part of the glue that holds it together.

A little research at my usual places indicates formaldehyde aerobically biodegrades rapidly.

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applestar
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Right. My understanding is that some kind of mold deterrent is needed in the glue.

toxcrusadr
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Hmm, I was not aware of that.



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