Help re Mast Spar Varnish

I have some McCloskey "Man-o-War" that I want to use
on porch handrails for a handicapped man. We live in
the desert where daytime temps are generally over 100
degrees F for 3-4 months of the year (up to 118 degrees),
and down to 10 degrees F in the winter for 1-2 months
(has been down to 0 degrees F in the past).

How many coats should I put on so the varnish doesn't
flake off?

Josephi

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