Is it really required to let new wood age for 4-6 weeks before applying DuroGrit?

This is more of a recommendation than a hard rule. It mostly depends on the particular wood used.

For example, fresh cumaru wood would definitely benefit from a few weeks of weathering to rinse out the extracts that the wood contains. After all, these might soften the coating when they migrate into the wood. Other wood species such as pine or ipé seem to be less sensitive to this.

We recommend that you test your local wood species or send a few samples to our lab to estimate if this is required in your particular situation.