AusBonsai

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I posted this last night in response to the awesome bench plans on the above link, but thought I'd post my question as a separate topic in the hope of getting more responses

I showed the plans to a member of my bonsai club and he mentioned something I hadn't thought of.
Is there any possible danger from any chemicals 'leeching' from the decking timbers onto the plants on the shelves below? We'll also be watering the plants (and therefore the decking) on a daily basis - more so than any regular decking might get wet.

Does anyone here know much about decking and the chemicals they contain? Hoping someone might have already researched this

Hi Bek , leeching may occur if decking oils are used and not sufficantly dried , that takes time . The tanins that can leech out of raw timber especially hardwoods will stain and are almost inpossible to remove so a sealer is used not an oil . Treated pine timber has had the cyanide removed back in the late 80's early 90's and doesn't effect any plants I have .

Cheers . Alpineart

If water is dripping from a shelf onto plants underneath, I would be more concerned about shading than chemicals.

I expect most timber sealers, eg Ultradeck, would leach very little. Unsealed treated pine would be much more toxic.

I would suggest using older ( seasoned) hard woods eg jarrah over freshly milled timbers especially merbau which contains a lot of tannins. Treated pine is nasty stuff with all outdoor use treated with differing levels of copper chrome arsenate they even recommend a thorough hand wash after handling which can't be good for the trees. There is a fantastic although pricey alternative called mod wood which is imitation timber decking which requires no oil or treatment and obviously no tannins If I was to build a permanent structure I would invest in this stuff.

The way the bench id designed, the shelve do not overlap, so you shouldn't get any leeching from the timber into your pots...

Interesting point.

I haven't noticed any issues with the bench that I have built.

Having said this I did lose a Banksia/Dryandra last year for no good reason and this may have copped a bit of run off.
As mentioned earlier I think the way the structure is designed means that very little run-off ends in your trees.

Personally I am thrilled with mine.

Thanks for the responses - I'll seal the decking timber anyway, to be safe. I admit I hadn't had a really close look at the plans to realize there was no overlap at all..

My benches and poles get the old fashioned linseed/turps mix. Let them dry for a couple of days, never had an issue.

Hi Bek,
I am also an SA Bonsai club member. I have many benches built from unsealed treated pine, and have no issues with them.
Consider one of South Australia's premier industries, grape growing and wine producing. What are all those grape vines held up with? Wires, and poles made from treated pine.

Good point I suppose, but I guess I was figuring that with smaller bonsai pots = less soil, so any chemicals that might leech would be more likely to have an effect as it won't 'spread' through a larger soil volume. But really, I'm probably just over thinking it. I do have a habit of doing that, haha!

Have you considered using one of those wood/plastic composite decking materials?

I don't have any experience with it at all, so I'm not recommending it, but maybe someone else on the forum has some experience with it and can help with advice.