[Public-List] Mast Beam Repair

[Don Campbell]

With the new epoxies like G-flex from Gougeon's,  you have better 
materials than  we had even 2 years ago. G-flex was developed to 
overcome the problems with normal epoxies of adherence and strength of 
joints with teak and mahagony.   G-flex has the strongest modulus of 
elasticity of any epoxy in production so far. If you like the look of 
oak, you might want to call them in Michigan and ask about the reaction 
for red oak . It may make some sense to switch to white oak if there is 
better adherence and you would still have a very attractive beam.to look 
at. White oak has a better reputation for lasting than red oak and the 
really good English white oak will last in soil for 50 years per inch of 
heartwood when used in the construction of wooden henges (similar to 
Stone Henge but made of wood). There was an interesting article on wood 
henges in Scientific American about 35 years ago for that information.
    John has mentioned acids in red oak. Normally plants do not have 
much of an imbalance of ionic charges so these are organic acids but 
strong oxidizers as well . I do know that with red oak particularly,  
that if it sits on steel for long as the board is cut from the log on 
the sawmill, it turns very black, very quickly. The iron in the steel is 
oxidized and the oxide sticks to and discolours the wood. I have never 
tried litmus on red oak sap though. If this is the case that there are 
acids in the wood, every time it gets wet, there is a replacement of the 
hydrogen ion and so the acid reaction continues again, the same way you 
add just water to a wet cell battery.
Don #528


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