Polyurethane and Paint:
Trends change quickly in the world of decor and design, and it is likely that you will want to keep up with the times. Wood furniture often comes with a polyurethane varnish or lacquer that prevents an easy or immediate decor change. But with careful preparations, you can paint over finished wood in your home and update its look. It requires some patient sanding and oil-based paint products to adhere to the plastic and polyurethane finishes on wood and commercial wood furniture. Here at Painters in Austin, we will wake you through the tips and tricks to make this job easier!
Polyurethane coatings are made with mineral oil solvents or may be a water-based polyurethane, so the answer depends on what you are repainting with, and which polyurethane you are painting over. Painting over any solvent based paint or finish with a water based paint, latex, or acrylic can be problematic, since even after the oil solvent is dried and the paint is cured, there may be some surface solvent retained on the paint, and water based paints don’t adhere well to the surface. Add the fact that many polyurethanes are gloss or semi-gloss, the new paint may not bite as well as you would like for it to.
You can paint over a surface of polyurethane varnish if you prepare it properly. Polyurethane is typically hard, durable, and glossy, and it is these qualities that make a finish vulnerable to chips and flaking. You don’t have to remove all the varnish before you start painting. Preparation will pay off in the long run by providing a long-lasting finish. Here’s how to go about with it:
Things you’ll need:
- Clean, lint-free cloths
- Mineral spirits
- Wood filler
- Protective face mask
- Fine-grade sandpaper
- Liquid sandpaper (optional)
- Oil-based primer
- Oil-based topcoat
- Dampen the cotton rag with the the trisodium phosphate solution. Wipe away all dirt, grease and grime from the surface of the wood, scrubbing away at any tough stains. Let the wood air-dry before proceeding.
- Sand the wood with a sanding sponge, power rotary tool, oscillating sander or sanding block until the varnished wood is smooth and the wood has lost its gloss and sheen. Use lower grit sand paper for rougher finishes and thicker varnishes. Wipe away any dust residue leftover from sanding with a tack cloth.
- Apply a thin coat of primer onto the wood. Apply in careful, even strokes to avoid any thick splotches of primer in isolated areas. Let the first coat dry to touch.
- Apply a second coat of the primer. Allow to dry overnight. Sand until the primed surface is smooth to remove uneven textures due to blotches in the primer application and from the brushstrokes.
- Apply a single coat of the enamel paint in the same manner of application as the primer, using long and even strokes across the surface of the wood. Let the first coat dry to touch before applying subsequent coats of paint.
- Avoid “one-coat” paints; they are expensive and do not provide a long-lasting finish. If you do inadvertently sand back to the wood, you need to make sure that your primer is capable of stain-blocking, as natural wood can bleed resins that will force their way to the surface and spoil the painted finish.
- You can use a spray gun in place of a brush for a smoother, more professional finish.
- Apply a wipe-on polyurethane varnish to protect the paint job if desired.
- Oil paints take a lot of time to dry. If time is an issue, substitute the oil-based enamel paint with a high-quality 100% acrylic paint.