when good decks go bad

[john@AEC 37]

G'day

A friend of mine had a deck built around the pool over summer (that's winter to you) and ....

The builder coated the timber, some parts twice, soon after laying it, with Linseed Oil - a vegetable oil, from the seeds of the Flax plant. Being a vegetable oil it is great food for mould. And guess what... is that mould growing in those boards? or is it tannins etc reacting with the Linseed Oil?

But wait there's more... the decking boards are splintering, and I mean SPLINTERING. Not those annoying little ones, these are more like spears that get stuck in the soles of your feet (1/4 to 1/2 inch long and very painful, especially when the last piece won't come out).

Does anyone have any clues as to what could be causing the timber to split/splinter?

This last summer has been drier and milder than average, although there were still more than a few hot days (100F +) and heavy storms, the deck faces north (into the sun - that's south to you).

The timber is "Yellow Balau" - a hardwood from South East Asian rainforests (http://www2.dpi.qld.gov.au/hardwoodsqld/13214.html).

Any help will be appreciated, as it is a shame to see such a great deck ruined.

[seymore 90]

WOW hardwoods splintering like that i would ahve never thought that could happen??

Looks like mildew to me....do a test spot with some bleach to verify the mold.It's not suprising for it to come from the linseed oil and veggie oil

The cracking boards are dry from the sun and you're saying this wood was just built and the linseed oil was applied 3-4 mths ago?

What are you choices for stain down under mate?

[john@AEC 37]

Hi Shane

That's correct, building started last Sept/Nov and the decking boards were completed in mid December.

The owner wants the builder to replace the worst of it... BUT... he's too busy with the next big job to even complete this one, let alone do fix ups.

As for stains and oils... there is Cabot's, Feast & Watson, and Intergrain (all made by Orica) plus a couple of others made by the other big international paint company, and a couple of small time independants. Flood have recently started pushing Spa'n'Deck - and some of the pro's are using it. I've started using a locally made product, it's great to be able to meet the owner & scientist - the company only does timber protection products.

Thanks for the thoughts

[Beth n Rod 1,279]

G'day

A friend of mine had a deck built around the pool over summer (that's winter to you) and ....

The builder coated the timber, some parts twice, soon after laying it, with Linseed Oil - a vegetable oil, from the seeds of the Flax plant. Being a vegetable oil it is great food for mould. And guess what... is that mould growing in those boards? or is it tannins etc reacting with the Linseed Oil?

But wait there's more... the decking boards are splintering, and I mean SPLINTERING. Not those annoying little ones, these are more like spears that get stuck in the soles of your feet (1/4 to 1/2 inch long and very painful, especially when the last piece won't come out).

Does anyone have any clues as to what could be causing the timber to split/splinter?

This last summer has been drier and milder than average, although there were still more than a few hot days (100F +) and heavy storms, the deck faces north (into the sun - that's south to you).

The timber is "Yellow Balau" - a hardwood from South East Asian rainforests (http://www2.dpi.qld.gov.au/hardwoodsqld/13214.html).

Any help will be appreciated, as it is a shame to see such a great deck ruined.

On of the characteristics of Balau is that it has a prickly feel to it. We bought deck furniture and one of the tables and two of the chairs are Balau. I have run my hand over the table and gotten a splinter from it. It has little pinhole pores. That is the problem. If you can sand it after cleaning, I would suggest that. Then I would seal it, scuff sand it, and seal it again. This may (or may NOT) help to fill those pinhole pores that are the beginnings of splintering. The sealing method I described is more akin to furniture finishing, but I am not sure you will be able to deal with the splinters any other way. If you choose to replace the boards, use Ipe instead if available and use anchor seal on the ends. We just put Wood Tux on our Balau, but not long enough ago to do you any good. If you can't get Wood Tux, try Cabot's Australian Timber Oil, if you can't get that, try Sikkens SRD. I know some people prefer parafinnic oils, but for your problem, I would suggest a little film followed by close observation to make sure that if the finish begins to fail anywhere you can catch it right away.

I have never seen a Balau deck, but based on what I have seen with Balau furniture, I would guess your problems will be ongoing. It's the wood.

Beth :cup:

see links below....

Profiled Timbers - Hardwood Profiles Specification

http://www2.fpl.fs.fed.us/Techsheets/Chudnoff/SEAsian_Oceanic/htmlDocs_seasian/shorea_spp_balau.html

[RPetry 564]

John,

The builder used just linseed oil, without added mildewcides / fungicides? If so, that has got to be some type of mold / mildew / fungus.

What is troubling is the close up picture. It looks like the discoloring is beneath the surface, or into the substate of the wood. Have seen this in the past here in the States. A major manufacturer of questionable quality linseed oil based wood stains did not use effective mildewcides for years.

I would try Shanes suggestion of testing a spot with bleach. If that doesn't work, on some woods a very long, and I'm saying 4-6 hours of dwell time of a strong NaOH solution may work. But its murder on the wood and near impossible to do.

[Beth n Rod 1,279]

Balau will do that. The pinholes are deep enough that if you get mildew down in them, it's a a pain. If you look at the pattern, dots with streaks, you can see the mildew went into the pinhole and followed the length.

You might try a couple test spots for different solutions and see what works best. Don't forget to neutralize. I would still sand it before you finish it. Balau has a tough hardwood, but not a very strong sapwood, which adds to the problems. The owner needs to know this wood is very prone to splintering. It will come back in time is my bet.

Beth

p.s. our table started to mildew last year, I hit it with a percarb which seemed to stave it off fine, and then this spring we stripped the table, sanded it and sealed it.

[john@AEC 37]

Thanks for the thoughts and replies

I'll try and get out there during the next week and have another good look at it - especially the splintering and how deep the mould is.

Yes, the builder says it was just straight linseed oil, so no additives. Thanks for the tips on resealing products - I was thinking a film product might help, or at least keep applying oil untill no more will soak in. Sikkens looks great when new but it doesn't last well (our climate would be similar to Texas), would Flood's Spa'n'Deck work?

Thanks again:lgbow: