Wood Window Restoration Basics

Updated: Apr 16

Tips & Tricks for Window Restoration Suggestions Using Swedish Windowcraft Methods:

There are a variety of methods and techniques for wood window restoration but below are the most basic steps to achieve the best results for a full restoration using Linseed Oil Putty and Linseed Oil Paint. (Ottosson brand, Viking brand)

To prep, the wooden sash should have all the old paint/putty removed using infrared, the glass carefully put aside and cleaned, and all necessary repairs/Dutchman repairs completed. There is no better option that replacing bad wood with new wood vs. using modern filler, putty, or epoxy products.

Sash can be “primed” ahead of time with a 30/70 ratio of 30% Linseed Oil Paint and 70% Purified Linseed Oil if so desired or "primed" after shellac is applied to the glazing grooves.

Step 1: Shellac

Apply a substantial coat of dissolved shellac flakes (mixed in denatured alcohol 24 hrs ahead of time in order to achieve a thick syrup like consistency) to glazing grooves/rabbets.

Allow to dry. Once dry, carefully remove any shellac outside of grooves if needed with a sharp scraper.

Step 2: Backbed with Linseed Oil Putty

Massage Linseed Oil Putty until warm and soft. Apply to the glazing grooves/rabbets.

Avoid trapping air bubbles in the putty as you apply.

Backbedding putty can be a softer consistency then the consistency used to glaze.

Step 3: Install glass and glazing pins.

Press down glass carefully until snug against groove/rabbet.

Style of glazing pins can vary – completely based on personal preference.

Use wooden spacers if needed between glass and frame to suppress excessive movement but avoid a very tight fit.

Step 4: Glaze

Apply Linseed Oil Putty with putty knife.

Smooth carefully, creating clean, sharp corners.

Carefully dust putty with super fine pumice powder or whiting/chalk if needed.

Possible to use the fine pumice powder or chalk to soak up excessive oil on the glass.

Step 5: Paint immediately with Linseed Oil Paint.

Mix Linseed Oil Paint well before each use.

Use a soft, stiff bristle brush and apply relatively thin, even coats of paint.

Paint 1/16-1/8 onto the glass to create a proper seal.

Putty needs to be coated with undiluted Linseed Oil Paint at this stage.

Do not apply 30/70 primer.

Apply 2-3 undiluted coats of Linseed Oil Paint onto the putty line and onto the glass.

Apply in 60+ degree temps and with good air circulation.

Each coat should be completely dry before the application of the next.

Step 6: Trim

Once final coat of paint is fully dry, trim back paint on glass if needed for an attractive sight line. Use sharp glass scraper against a long spackle or drywall knife.

Paint should be 100% dry in order to achieve a clean line.

If it begins to smear during the trimming process, stop and allow to dry further before trying again.

See the window restoration videos on the Earth+Flax YouTube Channel to learn more.