Step 5: Apply a coat of sealer

Written by Tagawa | Aug 20, 2026, 7:55:48 AM

Tips for Applying Plaster: Part 5

Applying a sealer prevents the plaster from being absorbed into the substrate and evens out the surface, which helps prevent uneven coating. It also acts as an adhesive when applying the plaster.

Furthermore, on substrates where tannins or stains may surface, applying a thorough coat of sealer can prevent these substances from bleeding through into the plaster.

Although a sealer is applied to suppress the seepage of tannins, it may not be possible to completely stop them from seeping through.

Substrates and Areas Where Sealer Should Be Applied

① Vinyl wallpaper, paper wallpaper, fabric wallpaper

② Gypsum board

③ Mortar and Concrete

④ Sand-plaster walls, fiber-reinforced walls, and Kyoto-style earthen walls

⑤ Plywood and Particleboard

How to Apply Sealer

① Shake the sealer well before pouring it into the drip tray. Be careful not to pour too much at once.

② Start by carefully painting the details—such as corners and the edges where the floor meets the baseboards—with a brush.

③ For larger areas, use a large brush, a trowel brush, or a sponge roller to apply the paint in one go, ensuring no spots are missed.

④Once the sealer has dried—after about 2 hours—apply a second and third coat, building up the thickness with each layer.

Tip! It’s the details that make it beautiful

Be sure to apply a thorough coat of sealer to the upper edge of the baseboard where it meets the floor and wall. Since baseboards are often made of wood, tannins can seep out of the baseboard and stain the lower part of the wall where it meets the baseboard.

DIY Plaster Video Tutorial#3: Sealer Edition

In this episode, we’ll cover the preparatory steps for applying plaster with NURI2, including how to apply sealer and why it’s necessary! Let’s take a look at how to use the base material!

DIY Plaster Video Tutorial#10: Sealer Special Edition (Tannin)

Here’s how to deal with it when “tannin” seeps out!