I have a job where I need to make 4 crates that are being shipped to China.
I can purchase materials(wood) locally that have the necessary bug stamp. I was wondering once I have
fabricated the crates, will I be able to use a clear polyurethane to protect the crates form moisture?
Yes you can use a protective coating on your crates. I personally use Minwax Polycrylic clear satin water based protective finish; 3 coats worth. I also only use man made wood products, usually plywood and stencil the crates 100 % Plywood.