Anti Freeze wood rot treatment discolouration?

by Dave

I am writing in reference to my wife Ann Marie's boat Helios, featured on this site.

After reading the section on wood rot and its treatment, the recommendation is to use ethylene glocol used in antifreeze or borate solution.

My question is does this mean actually use antifreeze or use ethylene glycol.

Having looked at antifreeze here in Ireland, I cannot find any which does have some type of colour to it: blue luminous green or red.

If the intention is to use anti freeze would these not discolour the wood and leave some type of residue which may stop adhesion of varnish later?

Also I'm assuming that since we are taking every thing back to the wood, for re-painting/varnishing, the whole boat needs this treatment.

What is the recommended method of applying the stuff.

Is it a quick lick with a brush or does it need to soak right in and, how then would you know if it had?

After applying this treatment in the correct way does the wood need to be re varnished straight away or can it wait until we are ready to final paint the hull.

I'd like to be sure we do it correctly first time so as to avoid a future major overhaul for as long as possible.

All help,but, especially from the person who wrote the article, would be greatly appreciated.


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by: Dave

Thanks a million Mike, that clears it up perfectly.

Though we both have a lot of practical experience, restoration is a new field for us, and we'd like to do her right.

As such your sage like advice is invaluable as are all the comments.

Go raibh mile maith agaibh. (irish for thanks)

by: Mike

Hi Dave,

It is the glycol that kills off the rot spores, antifreeze just happens to be the most convenient way, for you and I to procure it in small quantities.

The dyes that are used are normally so weak that they will hardly discolor the wood.

One reason why glycol/antifreeze works so well is that it is water soluble so it will penetrate dry and even wet wood.

And the dye in the antifreeze is also water soluble so any traces can be washed off easily.

You can paint it liberally around anywhere you think there may be rot spores, the wood will soak it up easily so use plenty, just beware not to splash too much as you don’t want to be breathing it in, (though I don’t think it is as toxic as that epoxy the previous owner used).

hi guys
by: Dave

Thanks for your replies,
I'm afraid a boat of this vintage isn't going to have some rot somewhere.

We did find some.

It came from bad maintenance from a previous owner.

Instead of repair a bit if impact damage on one side the plank was fibre glased over.

This became apparent after taking off more of the paint.

Still for the most part she's pretty good.

Anyway it needs sorting.

So is it actually antifreeze? or ethlene glycol that's used.

I'm thinking of looking for that clear product, any recommendations, brand names, etc?

by: Anonymous

If you do find any rotten wood, you need to cut it out cutting well back into the sound wood.

Then as treat the exposed end grain with the fungicide/antifreeze/borate.

Any rot spores that may have spread into the sound wood will have traveled along the path of least resistance, eg. along the grain.

Once, whatever you have used, has had a day or two to soak in and do its worst, the surface can then just be cleaned off and painted as normal.

If you do need to treat areas which are going to be clear varnished then it probably best to use a clear fungicide, there are various brands on the market.

If you do decide to treat the wood with creosote as a preventative measure it must be allowed to soak in and dry completely before over painting and the paint must be of the oil based type.

Rot treatment
by: Mike

Hi Dave,

I got the impression from Ann Marie’s description of “Helios” that the wood was sound under all that paint.

If there is no rot then there is no need to even think about using ethylene glycol or any fungicide.

You could use a preventative such as coal tar creosote but even that isn’t strictly necessary as long as she is well painted and kept ventilated.

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