Beautiful cedar deck was originally finished with an acrylic deck varnish. It didn’t even last one year there was a total failure.  I had to sand the entire deck to remove the residual finish. I finished and preserved the deck with a combination of raw linseed oil and pine tar.  These products penitrate the wood and aren’t a film forming finish that just lies on top of the wood.  This deck is now headed in the right direction for a long life.