Wood Finishes for Decoupage

Instructions for Preparing Wood for Decoupage Projects

When planning a decoupage project on a wood base, remember the old saw, "Oil and water don't mix." For example, the most common decoupage glazes, Mod-Podge and Elmer's Glue-All, are water-based and will not adhere easily to wood that has been stained with an oil-based stain.

This does not mean you cannot mix media, but if you do, you must allow enough time for all solvents to properly dissipate - sometimes several weeks between coats, to get around this problem. Read A Decoupage Bleed Problem for more.

If you've already stained wood with an oil-based stain, you will need to seal it with an oil-based sealer or, better yet, go oil-based all the way and use an oil-based medium for your decoupage coating(s) (instead of Mod-Podge or Elmer's).

If you want to decoupage a piece of old furniture and are not sure what type of finish it has, find an inconspicuous spot to test your glaze. To want to make sure it adheres properly (no bubbles), dries completely (no tackiness), and is sufficiently durable for the intended use.

Mod-Podge over oil-based polyurethane may lift and separate under heavy use. It might be alright for wall art but would not work for a cocktail table.

If you plan to paint the wood, your choices are pretty straightforward. With Mod-Podge or Elmer's as your glaze, use (water-based) acrylic paints. With varnish as your glaze, use oil paints.

If you want, or have, a stained wood base for your decoupage project, the decision is a bit trickier because of the many types of wood finishes on the market and the sometimes misleading marketing. The primer below should help clear up any confusion.

Oil Finishes

Oil finishes and stains are not recommended for decoupage, so decoupers can skip to the Varnish section unless they want to know why.

Oils seep into the wood and penetrate the wood's fibers. Because of this, oil finishes cannot be built up to a thick coat like polyurethane or varnish. They offer less protection but are easier to apply, which is their primary advantage. Another advantage is that simply wiping on more oil can often repair minor scratches.

Varnishes (including Polyurethane)

Varnishes are oil-based and are one of the most protective finishes available. The level of protection increases with additional layers. The primary downside of varnishes is that they are slow drying. The long drying time can allow dust and dirt to settle and damage the finish. Because of this it is best to finish your project in a clean dust-free room if possible.

Varnishes are produced by cooking an oil and mixing it with a resin such as synthetic alkyds, phenolics, and polyurethanes. Polyurethane is a varnish made with polyurethane resin to make it more protective and durable.

When more oil is used than resin, the finish becomes more flexible. This type of varnish is called "spar varnish" and is ideal for outdoor use because the flexibility makes it more forgiving of seasonal wood movement.

Oil - Varnish Blends

Just to make things more confusing, finish manufacturers have introduced a blend of varnish and tung or linseed oil. These finishes are applied and act similarly to an oil finish but the varnish adds additional protection.

They will still cure in the wood like an oil finish and should not be used if you plan on building up layers on the surface.

Therefore they are not recommended for decoupage.

Shellac

Shellac is one of the few natural resins still in use today. Although not as durable as a lacquer or varnish, shellac still provides a modest amount of protection. The big advantage, and the reason the finish is still in use today, is that shellac is alcohol based which makes it very fast drying.

Because shellac is fast drying, it is less likely to collect dust like varnish. It is often too thick to apply with a brush and requires thinning with denatured alcohol before it can be brushed.

This finish also requires that you work fast with your brush and maintain a wet edge.

It is available in a range of colors from clear to an orange/amber color.

Orange/Amber shellac is known for the warm tones it gives wood. Stored shellac breaks down over time, so be sure to purchase a fresh can, and don't use anything over a year old.

Lacquer

Lacquer is a solution of shellac in alcohol, often colored with resin from the gamboge tree or stigmas from the Old World saffron crocus.

It is used most often in furniture factories because its fast drying properties reduce dust related finish problems. It is usually applied with a spray gun although "brushing lacquers" that cure slowly are also available.

If you choose to spray a lacquer finish be aware that the fumes are hazardous to your health and the dry dust can be explosive.

Water-Based Finishes

Because of increasing environmental concerns a new class of finishes has been developed. These "water-based" finishes are often marketed as "polyurethane", "varnish", or "lacquer" which is technically incorrect and causes much confusion.

You can tell if a finish is water-based because the can should mention "water cleanup" as an added feature. "Water-based" finishes are basically latex paint without a pigment.

The two primary downsides are that they tend to hold visible brush marks and are less durable than the more conventional finishes. They also tend to bubble with brushing.

You'll want to use a synthetic bristle brush and try not to over-brush the surface. Also try to avoid temperature and moisture ranges that exceed indoor conditions. Moisture or temperature ranges on either end of the scale can cause drying problems.

For more on decoupage, visit The Decoupage Index Page.