Painting/oiling Macrocarpa Vege Beds

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Paul1977

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#279527 21-Oct-2020 13:42

The other half is wanting to put in some raised Macrocarpa garden beds for growing vegetables.

I hate the look of timber once it silvers off - so from a food safety standpoint, can these safely be painted or oiled on the outside? The sides will we 100mm thick, so I would have thought it would be fine but don't really know?

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MikeAqua

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#2589748 21-Oct-2020 14:26

You'll be fine oiling the outside.

Your main issue will be with oiling the tops, as some of it will run off into the garden.

Conqueror oil is biogro approved. It's a spraying oil, not a timber oil, but it might work.

I suspect any sort of varnish or similar will blister off as the timber absorbs moisture

Mike

qwertee

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#2589780 21-Oct-2020 14:58

See my post on this topic

Forums › Home Workshop DIY › Building raised vegetable gardens - need tips & advice

cheers

timmmay

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#2589810 21-Oct-2020 15:29

100mm thick wood sounds expensive.

Paul1977

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#2589814 21-Oct-2020 15:34

qwertee:

See my post on this topic

Forums › Home Workshop DIY › Building raised vegetable gardens - need tips & advice

cheers

Thanks, not a lot in there about exteriors finish options though.

Paul1977

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#2589815 21-Oct-2020 15:37

timmmay:

100mm thick wood sounds expensive.

Macrocarpa sleepers. Not the cheapest in the world, but should last a good number of years.

Paul1977

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#2589817 21-Oct-2020 15:45

Can I use something like a decent penetrating oil, or a penetrating timber stain like Resene Woodsman?

I think trying to find something certified as food safe will be difficult, so just trying to determine if anything like the above could leech through 100mm of timber into the soil?

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qwertee

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#2589836 21-Oct-2020 16:08

Once you decide on a finish, I suggest that you get some off-cuts and paint on the stains using the colours you like

I did 6 test stains and with 1 coat and 2 coats.
Mitre10 painted them on for free , but I had to buy the test pots from Resene and Bunnings.
Didnt like the woodsman colours and finish from Resene. Too chocolatey!

Ended up with Watty Aquatech oil stain, water based. Being water based was a safer option and I doubt it will leech through 100mm macrocarpa.
Mine are 50mm thick.

My understanding was that oils need yearly re-painting, but the stains fare better and maybe need a stain it every 2-3 years.

Do put up some photos of the build when you have finished.

Paul1977

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#2589891 21-Oct-2020 16:38

qwertee:

Once you decide on a finish, I suggest that you get some off-cuts and paint on the stains using the colours you like

I did 6 test stains and with 1 coat and 2 coats.
Mitre10 painted them on for free , but I had to buy the test pots from Resene and Bunnings.
Didnt like the woodsman colours and finish from Resene. Too chocolatey!

Ended up with Watty Aquatech oil stain, water based. Being water based was a safer option and I doubt it will leech through 100mm macrocarpa.
Mine are 50mm thick.

My understanding was that oils need yearly re-painting, but the stains fare better and maybe need a stain it every 2-3 years.

Do put up some photos of the build when you have finished.

Thanks. Will still be a while, landscaping is just starting.

timmmay

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#2589896 21-Oct-2020 16:52

I know a guy who works for cabots who do stains, part of dulux. I'll ask him.

timmmay

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#2589967 21-Oct-2020 18:19

My friend says "anything Cabots make is fine once it's dried as it's all nontoxic. People use it all the time to oil/stain planter boxes/veggie gardens. Oil based would be best."

qwertee

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#2590119 22-Oct-2020 08:28

I left my macrocarpa raised bed to dry for about 4 weeks before staining.

Observed about a 4-5mm gap at some of the mitred cap corners and sides after this time frame as the wood dried.
This was all flush when first assembled.

cheers

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Paul1977

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#2590131 22-Oct-2020 09:10

timmmay: My friend says "anything Cabots make is fine once it's dried as it's all nontoxic. People use it all the time to oil/stain planter boxes/veggie gardens. Oil based would be best."

Cheers