I remember watching my dad repainting the skirting and doors in our house when I was a child. He would always sand back to pretty much bare wood before applying an undercoat and then topcoat. I will admit that it left a really nice finish, but it seems like a lot of work and something I have never done myself. I have always cheated and taken the easy route when painting over varnished wood, what is the easy route you ask? Keep reading to find out.
Can You Paint Straight Over Varnished Wood?
Yes, you can paint straight over varnished wood. There are two options open to you that I would highly recommend. You can sand the varnished wood lightly with a high grit paper, this will give your paint a better surface to key to. The next option is to use a primer such as Zinsser B-I-N. This can be painted straight onto shiny surfaces like varnish and gloss with no problems.
Using Zinsser BIN
BIN is a shellac-based primer from Zinsser, I have written about it on here extensively as part of my which Zinsser primer to use post.
This primer can be painted straight onto shiny surfaces, surfaces such as varnish and gloss. And even better, it dries quickly too, meaning you can overcoat it within hours. So no more sitting around waiting for your primer to finally dry.
I actually did a test of all three of the different Zinsser primers over varnish, you can find them here Can You Use Zinsser BIN Over Varnish here Can You Use Zinsser Cover Stain Over Varnish? and here Can You Use Zinsser Bulls Eye Over Varnish?
From my testing, all three of the primers worked but BIN worked really well.
I scratch tested the BIN using this woodblock and it did not chip or scrape at all, so the paint is thoroughly stuck on there.
This method also works really well if you are going from dark wood to a light colour. Zinsser BIN is a great stain and colour block so will help you to easily change from dark to light.
Sanding the Varnish
This is the second option for painting over varnish and is definitely the cheapest but also the hardest work. If you are going to sand varnish before painting then don’t use rough paper. You want something 120 grit or above.
If you use too rough sandpaper then you will gouge the wood and leave marks in it which will then show through your finish, so be careful.
The easy way to do this is to not try and take all of the varnish off and down to bare wood. instead, you just want to scratch the surface enough to allow your next coat of paint to stick to it.