Varnish, varnish, varnish

I'm calling it varnish, but I guess it's called polyurethane in English. Maybe that's just a category of varnish. It's water-based, and it's called « vitrificateur » in French. It gives the wood a "glassy" or vitreous finish. I find mentions of "polyurethane varnishes" in Wikipedia.

Here's the staircase drying after the initial wipe-down
with a wet rag. It took a while to dry.

Now that the weather has cooled down, I've been working every day at putting another coat of varnish on one part or another of the new staircase. First I varnished the railings upstairs with a couple of coats, and then the banisters running down the stairs with one good coat. They'll need another.

Looking down toward the ground floor after applying
the first coat of polyurethane varnish.

But I really wanted to get to work on the steps themselves. They were dirty with plaster dust and foot dirt. Each tread was covered with a sheet of cardboard that was taped to the front edge of the step. There were scuff marks on the risers from the heels of shoes — mostly my sandals, I know.

A closer look at the treads and risers
after one coat of varnish...

The first step was to take off the cardboard and, after vacuuming, to wash the whole staircase down with a damp cloth. I added a small amount of distilled vinegar to the water. The black scuff marks washed right off, but after the stairs had dried I realized the glue holding all that tape onto the front of the steps had left behind a sticky residue.

...and a look down from a different angle

I decided to try removing it with a product called White Spirit, which is a paint thinner and general solvent. I was worried about what that might do to the wood, but it turned out fine. I got off all the sticky residue. In some places, it took a little sanding too.

The building contractor left this portable scaffolding with us
for the summer. It'll help greatly with the painting job.

The actual varnishing was pretty easy. That part of the all-day project took only about 90 minutes. And I'm happy with the result. Now I have to apply at least two more coats of varnish to the parts that will be subjected to the heaviest wear — steps, risers, and handrails — before I can call it finished. And then figure out how to apply varnish to the underside of the stair.