The main structures are lacquered in black or clear varnish.
Sand it down lightly, slap on a couple coats of clear varnish, and they'd be set.
These can be protected by a final coat of clear varnish.
The whole exterior was covered with a coat of clear varnish to prevent tarnishing.
Finally, a new coating of clear protective varnish was applied.
He stripped the floor himself, then lacquered the concrete with clear varnish.
You might try a clear varnish that comes in aerosol cans.
After three years of experimentation, he created the clear varnish, which went into production by 1905.
When it dries, finish with two coats of clear varnish.
Similar to a clear varnish is an acrylic gel polish.