Shellac Sealer

Shellac Sealer

Shellac has been around for centuries. It is a natural resin secreted by the female lac bug on trees in the forests of India and Thailand. Traditional furniture makers and restorers favor shellac for its versatility and ease of use.

What is Shellac?

Shellac is a resin that is processed and sold as dry flakes, which are dissolved in ethanol to make liquid shellac. It can be applied with a brush, cloth, or sprayer. Its natural origin and glossy finish make it a preferred choice for many woodworkers.

Advantages of Using Shellac Sealer

• Quick Drying: Shellac dries quickly, often within 30 minutes. Multiple coats can be applied in one day.
• Non-Toxic: It’s a safe option for children’s toys and furniture since it’s non-toxic when dry.
• Adhesion: Shellac provides excellent adhesion to wood, forming a good base for other finishes.
• Repairable: Damaged shellac finishes can be easily repaired by re-dissolving the old shellac with alcohol.

Using Shellac as a Sealer

Shellac is commonly used as a sealer due to its excellent adhesion and compatibility with other finishes. It can be used as an undercoat, providing a flawless base for subsequent coatings of paint or varnish. This quality makes it especially valuable in refinishing projects.

Preparation for Application

Mixing Shellac

Shellac comes in flakes that require mixing with denatured alcohol. Using a ratio of two pounds of flakes per gallon of alcohol will create a good consistency for most projects. Mix well and let the solution sit overnight.

Sanding the Surface

Ensure the wood surface is smooth. Sand with progressively finer grit sandpapers, finishing with a 180-grit. Wipe off the dust with a tack cloth.

Applying Shellac

Stir the shellac mixture well before use. Use a clean brush or pad to apply the shellac. Work quickly and use long, smooth strokes to avoid lap marks. Allow the first coat to dry for at least 45 minutes.

Sanding Between Coats

To achieve a smooth finish, lightly sand between coats with a 220-grit sandpaper. Wipe away the dust with a tack cloth. Apply subsequent coats, allowing each to dry thoroughly. Three to four coats will usually suffice for a durable finish.

Using Shellac for Stain Blocking

Shellac is also effective as a stain blocker. It excels at sealing knots, sap streaks, and other discolorations in wood. This prevents these stains from bleeding through the final finish.

• Apply a coat of shellac to the problem area.
• Let it dry completely.
• Proceed with your regular finishing process.

Cleaning Up After Application

Clean brushes and pads used for shellac application with denatured alcohol. It quickly dissolves any remaining shellac, extending the life of your tools.

Maintaining a Shellac Finish

A shellac finish is durable but not impervious to damage. It can be easily maintained by wiping with a soft, damp cloth. Avoid using harsh cleaners or abrasive pads. If the finish becomes worn, applying a fresh coat over the existing shellac will rejuvenate it.

Aging and Shelf Life

Shellac has a limited shelf life when mixed. Flakes can be stored for several years, but mixed shellac only lasts about six months. Always date the mixture and test on a scrap piece before use to ensure it’s still good.

Common Issues and Solutions

• Blushing: This occurs when moisture gets trapped under the shellac. Reduce humidity or apply another coat to fix it.
• Fish Eye: Caused by contaminants on the surface. Clean thoroughly before application.
• Streaks: Can be a result of uneven application. Sand lightly and reapply.

Using shellac sealer can significantly improve the quality of wood finishing projects. Its unique properties of quick drying, non-toxicity, and ease of repair make it a valuable tool for both amateur and professional woodworkers. Understanding the proper preparation, application, and maintenance will ensure a beautiful, lasting finish.