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Burning hardwood for ash

My dad plans on burning some old hard wood left over from 40 or 50 years ago when they renovated the house. He wants to burn it so he can use the ashes on the garden as pot ash. I have tried to convince him this is a bad idea, but he will not listen to me. I dont know if there are any preservative in this wood, I have heard of some woods containing chemicals or arsenic as preservatives. I am concerned if he burns the wood firstly potentially toxic smoke, but also if he does use the ash on the garden and there are these toxins in the wood then surely they will be present in the ash and will in turn end up in the fruits and veggies of the garden, eventually making their way into the body of whomever eats the produce.

The annoying thing is my parents have a box of sulfate of potash in the garden shed, and I have tried to tell him this is the same thing. He is a stubborn old man who will not listen. He also likes to add additive to the garden when they are not needed, and fertilize things when ever he feels the urge.. Also likes to prune fruit trees in the dead of winter. I once had a macadamia tree which was doing well for its first two years of life, it suddenly died following a visit from dad.. when I asked if he had done anything to it he said "No I didnt do anything to it, I only gave it some fertilizer"... Fertilizing my tree constitutes to doing something to it..

It was an Australian Native, it did not need fertilizing... I believe this is why it dropped all its leaves and died.

Anyway back to the burning of the 50 years hardwood (I think they're roof beams but I am really not sure)

What I want to know is would this wood contain anything toxic? I will keep trying to convince him not to burn the wood, but past experience tells me this will make not a scrap of difference to his mind.

I really hate when people burn stuff in there gardens, I am pretty sure it is illegal but aside from that, I personally dont like it because it dirties the environment. I really enjoy fresh air and I know I'm not the only one.

Any advice would be immensely helpful and really very much appreciated.

Stay safe all

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Comments

EricL

Hello @AngryBird

Thank you for sharing your concern about burning hardwood to ash.

Your caution is well placed. Externally treated timber and pressure treated timber are not recommended to be burned. These types of timber when burned produce toxic fumes which can be harmful and fatal. Older preserved timber used heavy metals in their preservation and remain in the ash and is highly toxic.

It is difficult to tell what type of treatment has been applied to older timber. But the general rule is that timber that has been in the open for more than a year and has not rotted will often have some form of chemical treatment on it. I can understand your difficulty convincing your father that burning old hardwood is not safe. I've run into the same issue with my mother trying to convince her that online banking is safe.

Perhaps you can offer a compromise to use the timber as sleepers or as pathway borders. Perhaps a garden project that can utilize the timber to bypass the option of burning.

Here is a handy link: Treated and Contaminated Firewood

Let me tag our experienced members @TedBear and @JDE for their recommendations.

If you need more advice or information, please let us know.

Eric

TedBear

https://www.workshop.bunnings.com.au/discussion/comment/14379#Comment_14379

Hi @AngryBird , although I agree with @EricL in general about the risks of burning treated timber....

given that the timber was used for house construction 40-50 years ago, it is quite possible that it is Jarrah, (distinctly beautiful red grain when the outer grey layer is removed... rasp a bit it or saw through a piece to see).

If so, it won't have been chemically treated, so it is safe to burn.... but that would be almost criminal to do so.

https://www.redmondsawmill.com.au/products/structural-timber/

If it's jarrah, then it is hard to come by and highly desirable for furniture and other uses, so to burn it is an awful thing to contemplate.

It will also have a lot of gum in it, so probably isn't the best for putting on plants anyway.

In any case it is a mistake for people to think that Potash is just pot - ash and made from the ash of wood.

Potash is potassium salts, which is the fertilizer. It can be leached out of some timbers, but is often extracted from other sources.

And you are right to protest about creating extra smoke for no good reason.

Good luck with the convincing - it's a hard task with family,

AngryBird

https://www.workshop.bunnings.com.au/discussion/comment/14379#Comment_14379

Thank you Eric for your reply, and the links. I have printed out the document in the link you have in your post and I will try again to change my dads mind.

He has spent the last two days with the angle grinder cutting an old commercial beer keg (which he lawfully purchased, all totally above board there at least) building a vessel to burn the wood in.

I feel I have a better shot now armed with this new information provided by yourself and TedBear.

Kind regards

AngryBird

https://www.workshop.bunnings.com.au/discussion/comment/69740#Comment_69740

Hi Ted,

thank you for your information, the prospect of it being Jarrah is quite exciting and I will have to check it tomorrow. I will try and convince dear old dad yet again. Perhaps I will have a better chance now with this new knowledge.

Thank you for you help

Kind regards

AngryBird

Just an update here:

I have shown my dad the information provided by EricL and TedBear, and as expected met immediate resistance. Before I could finish reading out the information to him, about potential preservatives in the wood, I had been interrupted with his best/classic defense "but its hardwood" as if this somehow absolves it of any additives or preservatives. He seems to think that if it is hardwood, it automatically has no chemicals/additives or preservatives.

When I said it is illegal to burn and not good for the environment he says "Im not going to make a big fire, just have it smoldering for a long time".. I think this would still make smoke. And when told that potash is not just any wood ash, his mouth said "okay" but I got a look that said 'I dont care what you say, I'll do what I like' and I know he'll just burn the wood when he thinks no one (me) is looking. Only other thing I can do is hope it is Jarrah and appeal to his desire to get some money for the wood. But some how I just dont think I will be that lucky. I will upload some photos of the wood later if I can. and hope to identify it, I know this is unlikely.

Cheers all.

EricL

https://www.workshop.bunnings.com.au/discussion/comment/14389#Comment_14389

Hello @AngryBird

I'm sorry to hear you were not successful in convincing him. I suggest enlisting the services of a seasoned builder to take a look at the timber and identify what type of wood he has. You could also enlist the services of his close respected friends.

Please keep us updated, we look forward to the wood being repurposed.

Eric

AngryBird

https://www.workshop.bunnings.com.au/discussion/comment/69753#Comment_69753

Hi Eric,

I may have got somewhere via mum, she said its not worth risking giving family cancer down the track if they have eaten the produce and that gave dad a pause and he agreed with that. But time will tell if this was enough.. I havent given up yet. and I have left the literature around for him to read, when he thinks no one is looking. Fingers crossed the message gets through.

Thank you for all your help.

Cheers

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