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Borax impregnation with vacuum press5/12
I started to use borax to help preserve construction wood. On douglas fir I only use it on the sapwood and on pieces that will not be exposed to rain even during construction, because I read it will be washed out in that case.
Now, I have thought of putting the freshly treated pieces of lumber in my vaccuum press to make the borate penetrate.
My vaccum press is a large Polyurethane bag and a pump. It would be easy to leave a few planks in the bag and yust slide the treated planks in the bag, on top of the first planks. My bag is 5 meters long and 1 meter wide, so i could do quite some wood in one go.
My goal would be the be able to let the borate penetrate enough to make it usable on pieces of lumber that might get some rain during the construction phase (which will last a few weeks maximum).
In terms of quantities, I only treat those pieces of lumber that have a large proportion of sap wood, so it's not a lot of wood...
My question is : will the vacuum bag method be efficient ? and how long would you think it will need to stay in the vacuum press ?
Almost all wood treating is only adding the preservative chemical to the outer layers of the wood. So, the question is how much chemical will you get in the outer 1/2" or so? Vacuum alone will not help penetration. Penetration is obtained when the vacuum is released. The borate solution will penetrate better if it includes a surfactant to reduce the surface tension of the water. With some species, the liquid permeability of the wood is so low that the borate will penetrate by diffusion only so vacuum does not help much.
You are aware that the borate chemical used is a special mix of borate.
I've thought about doing a test with some ink diluted in water to see what happens, but regarding your answer i'm afraight it won't do so much.
The chemical I use is boron salt, a fine white powder which I dilue in water. I'm in europe so I'm not very sure about the term "Borax", which I think is also a commercial name in the US ?
Anyway, would it than help to add some soap or dish washing liquid to the water ?