On May 29, 9:39*pm, mm wrote:

snip

How DID polyurethane become so doggone popular?

Simply put, it cornered the market based on far better performance in
virtually every paint and varnish category.

*I used it myself in
on my dining room parquet floor and it only lasted a few years in the
heavily traveled parts. *At the time, I thought I should have used
varnish of some sort.

Odds are you simply brushed on a couple of light coats of polyurethane
varnish (yes, polyurethane is varnish by definition). If you had
followed the directions on the container you would have found
recommendations for many more coats with sanding and wiping in
between, for a highly durable finish. Your poor results are not the
fault of the product, but insufficient and/or improper application.

Joe