How To Make Sanding Sealer

Sanding sealer is a crucial component in woodworking, especially when you’re aiming for a smooth, flawless finish.

It’s applied before the final finish to seal the wood grain, making the final sanding process easier and ensuring a smooth surface for the final finish.

In this article, we’ll delve into how you can make your own sanding sealer at home.

Key Takeaways:

  • Sanding sealer is used to seal wood grain and provide a smooth surface for sanding.
  • It can be made using shellac or lacquer, diluted with denatured alcohol or lacquer thinner.
  • Using sanding sealer can save time, reduce the amount of final finish required, and ensure a smooth, glossy finish.

What is Sanding Sealer?

Sanding sealer is essentially a diluted finish, often made from shellac or lacquer, that’s designed to seal the wood grain and provide a smooth surface for sanding. It dries quickly, sands easily, and prevents the wood from absorbing excessive amounts of the final finish.

Why Use Sanding Sealer?

  • Smooth Surface: It fills in the wood pores and creates a smooth surface, which is essential for a glossy finish.
  • Saves Time: It dries quickly and sands easily, making the final sanding process faster.
  • Economical: Using sanding sealer can reduce the amount of expensive final finish required.

Making Your Own Sanding Sealer


  1. Shellac or Lacquer
  2. Denatured Alcohol or Lacquer Thinner


  1. Shellac-Based Sealer:
  • Mix a 1 lb cut of shellac. This means 1 lb of shellac flakes in one gallon of denatured alcohol.
  • For a pre-mixed solution, you can dilute a 2lb cut of shellac (like Bullseye SealCoat) to a 1lb cut using denatured alcohol.
  • Alternatively, buy dry shellac flakes and mix with denatured alcohol.
  1. Lacquer-Based Sealer:
  • Mix lacquer with lacquer thinner in a 1:1 ratio.
  1. Apply the sealer using a brush or spray system. Let it dry according to the manufacturer’s recommendations, usually a few hours.
  2. Once dry, sand the surface lightly with fine-grit sandpaper to achieve a smooth finish.

Note: Commercial sanding sealers often contain materials that can interfere with finish adhesion. It’s advisable to test on a scrap piece of wood before applying to your main project.

Alternative Sanding Sealer Recipes

  • Talc-Based Sealer: Mix 15% talc powder, 40% varnish, and 45% thinner. Adjust the consistency by diluting if it’s too thick.
  • White Glue Sealer: Mix 1 part Weldbond glue with 5 parts water. This creates a porous sealer, allowing stains to penetrate the wood evenly.

Relevant External Links:

Advanced Techniques for Making Sanding Sealer

Understanding the Components

Shellac vs. Lacquer

Both shellac and lacquer can be used to make sanding sealer, but they have distinct properties:

  • Shellac: This is a natural resin that’s dissolved in alcohol. It’s non-toxic and can be used for food-safe finishes. However, it’s less resistant to water and alcohol.
  • Lacquer: This is a synthetic finish that’s more durable than shellac. It dries quickly and offers a hard, durable finish.

Thinning Agents

The choice of thinning agent can affect the drying time and consistency of the sealer:

  • Denatured Alcohol: Used for shellac-based sealers. It evaporates quickly, leading to faster drying times.
  • Lacquer Thinner: Used for lacquer-based sealers. It’s more aggressive than denatured alcohol and can dissolve older coats of lacquer.

Customizing Your Sanding Sealer

Depending on your project, you might want to customize your sanding sealer. Here are some variations:

  • Tinted Sealer: You can add dye or pigment to your sealer to achieve a tinted finish. This is useful if you want to add a hint of color to the wood.
  • High-Build Sealer: For a thicker coat, reduce the amount of thinning agent. This will give you a sealer that builds up faster on the wood.
  • Fast-Drying Sealer: Increase the amount of thinning agent for a sealer that dries rapidly. This is useful if you’re working on a tight schedule.

Safety Precautions

When making and using sanding sealer, always work in a well-ventilated area. Both shellac and lacquer can produce fumes that are harmful if inhaled. Wear protective gloves and a mask, and keep the materials away from open flames.

Frequently Asked Questions

1. What is the primary purpose of a sanding sealer?

A sanding sealer is used to seal the wood grain, providing a smooth surface for the final finish. It ensures that the wood doesn’t absorb excessive amounts of the final finish, leading to a more even and polished look.

2. Can I use sanding sealer on all types of wood?

While sanding sealer can be used on most types of wood, it’s especially beneficial for woods with open or uneven grains, such as oak or mahogany. It helps in achieving a smoother finish on these types of woods.

3. How long should I wait before sanding after applying the sealer?

Typically, you should wait until the sealer is completely dry. This can range from a few hours to overnight, depending on the type of sealer and the environmental conditions. Always refer to the manufacturer’s instructions for specific drying times.

4. Can I use sanding sealer as a final finish?

While sanding sealer can provide a smooth surface, it’s not designed to be a final finish. It’s best to apply a topcoat over the sealer to protect the wood and enhance its appearance.

5. Is there a difference between sanding sealer and wood conditioner?

Yes, while both products prepare the wood for finishing, they serve different purposes. Sanding sealer seals the wood grain, making it smoother for the final finish. Wood conditioner, on the other hand, is used to prevent blotchy or uneven staining, especially in softwoods.

6. Can I tint my sanding sealer?

Yes, you can add dyes or pigments to your sanding sealer to achieve a tinted finish. This can be useful if you want to impart a hint of color to the wood before applying the final finish.

7. How do I store leftover sanding sealer?

Store sanding sealer in a cool, dry place away from direct sunlight. Ensure the container is tightly sealed to prevent the sealer from drying out or getting contaminated.

8. Can I apply sanding sealer over an existing finish?

It’s not recommended to apply sanding sealer over an existing finish. The sealer is designed to penetrate the wood, and an existing finish can prevent this. If you want to refinish a piece, it’s best to remove the old finish first.

9. How do I clean up after using sanding sealer?

For water-based sealers, you can use soap and water. For oil-based or solvent-based sealers, use the appropriate solvent, such as mineral spirits or denatured alcohol, for cleanup.

10. Is sanding sealer toxic?

While sanding sealer itself isn’t highly toxic, the fumes from certain types, especially those based on solvents, can be harmful if inhaled. Always work in a well-ventilated area and wear protective gear, such as masks and gloves, when working with sanding sealer.

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