How to Seal a Porous Item Before Resin Casting: A Step-by-Step Guide


Resin casting is a popular craft that allows you to create stunning and durable items. However, when working with porous materials like wood or ceramics, it’s essential to seal them properly to prevent air bubbles and ensure a flawless finish. In this article, we will guide you through the process of sealing porous items before resin casting.

Why Sealing is Important?

Before we dive into the how-to, let’s understand why sealing is crucial. Porous materials have tiny air pockets that can trap air bubbles when resin is poured onto them. These air bubbles can ruin the final result, leaving your project with an uneven surface. Sealing not only prevents this but also enhances the durability of your casted item.

Materials You’ll Need

Before we get started, gather the following materials:

  1. Porous items (wood, ceramics, etc.)
  2. Sandpaper (various grits)
  3. Sealant (epoxy resin, polyurethane, or wood sealer)
  4. Paintbrush
  5. Gloves
  6. Mixing cups and sticks
  7. Resin for casting
  8. Resin mold
  9. Heat gun or torch
  10. Safety goggles

Step-by-Step Guide

Step 1: Preparation

Begin by preparing your workspace. Lay down a plastic sheet or newspaper to protect your work surface from spills. Put on your gloves and safety goggles to ensure your safety throughout the process.

Step 2: Sanding

Start by sanding the porous item thoroughly. Use different grits of sandpaper to achieve a smooth surface. Sanding helps open up the pores and prepares the item for sealing.

Step 3: Cleaning

After sanding, wipe away any dust and debris from the item’s surface using a clean, dry cloth.

Step 4: Choosing the Sealant

Select an appropriate sealant based on the material of your item:

  • Epoxy resin: Ideal for a wide range of materials, including wood and ceramics.
  • Polyurethane: Suitable for wood surfaces.
  • Wood sealer: Specifically designed for wooden items.

Step 5: Applying the Sealant

Using a paintbrush, apply a thin layer of your chosen sealant evenly over the entire surface of the item. Ensure that the sealant penetrates the pores. Follow the manufacturer’s instructions for drying times.

Step 6: Sanding Again

Once the first coat of sealant is dry, lightly sand the surface again to remove any imperfections and prepare it for the second coat.

Step 7: Applying a Second Coat

Apply a second coat of sealant and let it dry thoroughly. This additional layer will further seal the pores and provide a smoother finish.

Step 8: Casting

Now that your porous item is properly sealed, you can proceed with resin casting. Mix the resin according to the manufacturer’s instructions, pour it into the mold, and carefully place your sealed item into the resin.

Step 9: Removing Air Bubbles

To eliminate any air bubbles that may have formed during casting, use a heat gun or torch to gently pass over the surface of the resin. The heat will cause the bubbles to rise and pop.

Step 10: Curing

Allow the resin to cure according to the manufacturer’s recommendations. This may take several hours or even days, depending on the type of resin used.


Sealing porous items before resin casting is a crucial step to ensure a flawless, bubble-free result. By following these steps and using the right materials, you can create stunning resin castings that will impress everyone.


  1. Is sealing necessary for all porous items before resin casting? Yes, sealing is essential for preventing air bubbles and achieving a smooth finish, especially when working with porous materials.
  2. Can I use any sealant for wood items? It’s best to use a wood-specific sealer for wooden items, as it provides better adhesion and protection.
  3. What if I don’t have a heat gun or torch for removing air bubbles? You can try using a drinking straw to gently blow on the resin surface to release air bubbles.
  4. How long does resin casting typically take to cure? Curing times vary depending on the resin type and manufacturer’s instructions. It can range from a few hours to several days.
  5. Where can I find high-quality resin and molds for casting? You can find a wide selection of resin and molds at craft stores or online craft supply shops.

Sealing porous items is a crucial skill in resin casting, and with practice, you can create beautiful and professional-looking resin creations. So, get started and enjoy the world of resin crafting!

Sharron Gimik
Sharron Gimik

Sharron is the founder and creator of Homestead Sparkle, Down Home Wicks, Bundt Cake Admiration, and Timbers Cove. She loves crafts of all kinds and started as a candle maker. She loves to bake and collect decorative cake pans too.

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