In the picture below is an offcut of deck board which was never used. I was wondering about the crystallisation that has occurred. Is that preserver? Is it harmless?
Looks like surface mould to me, caused by being stored with a lack of airflow. The pressure treatment should ensure it won't penetrate the timber, if indeed it is a type of timber rot.
I had something like this on some of my boards - I assumed it was something to do with the preservative reacting with the resin from the pine. - It occured more around areas with knots in...
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