Differences Between Wood Filler and Grain Filler

“Is grain filler the same as wood filler?” This is one question you’d surely ask if you’re somewhere between the construction and finishing stage of your project and you are wondering how to get that perfectly smooth surface.

Grain filler is a batter-like paste that you wipe onto wood, leave to set for a while, and then wipe off. It functions just as the name suggests; it fills the tiny pores of the grain and is available in several different colors; natural wood color, tints, and others. On the other hand, wood filler is a putty-like product used to fill gaps and cracks in large areas. Its thicker consistency makes it suitable for repairing wood from the inside. It doesn’t have the same color as the wood and would need extra staining.

Although they might seem the same and are sometimes used interchangeably, they are poles apart. There’s a lot explained in this article about these differences. Read on for more. This guide contains all you need to know about both of them.

Is Grain Filler the Same as Wood Filler?

Grain Filler

For open-grained woods such as oak, mahogany, and walnut, it is impractical to build up layers of standard wood finish due to large pores present in the wood grain. A grain filler helps seal these pores and leaves an evenly textured finish.

Grain fillers are made of a binder, i.e., wood finish, a bulking agent and a solvent. The binder can be water-based or oil-based. For water-based fillers, the binder can either be acrylic or urethane. For oil-based fillers, it is typically a combination of oil and varnish.

The type of binder used will determine the solvent you’d used. Water-based fillers use water as the solvent, whereas, for oil-based fillers, mineral spirits are used. Silica is used as the bulking agent in both types. This is because it prevents wood from shrinking and expanding in response to temperature and humidity changes.

Wood Fillers

To conceal a significant defect on a piece of wood, wood filler comes into play. Woodworkers use it to fill cracks in joints, nail holes, and other blemishes in their projects. Wood fillers are a little challenging to apply but are useful during any woodworking project or construction.

They are made by mixing wood residues such as sawdust or wood fibers with a binding agent. The binding agent could be petroleum or water-based.

Petroleum-based wood fillers can be used for outdoor projects. On the other hand, water-based fillers are best suited for indoor use.

Both types bind tightly to the wood and harden, adding to the structural integrity of the wood. They, however, do not improve the strength of wood joints like wood glue or mechanical fasteners.  

Wood fillers are only available in a single color and are not tinted. Try applying a small amount of the filler first, then some wood stain. Keep doing this until it matches your wood’s color.

How to Use Wood Filler?

Getting a wood filler to perform its job isn’t daunting once you have the right materials and the proper tutor. Follow our easy guide to learn how to use a wood filler.

Required tools and materials

To use a wood filler correctly, you’ll be needing the following;

  • Putty knife
  • Oscillating sander
  • Clean rags
  • Mineral spirits (or acetone if you are working with petroleum-based fillers)
  • Sandpaper
  • Tack cloth
  • Wood stain
  • Shop vacuum

Step 1: Mix the wood filler

To use wood filler, you need to first mix it up in a container with a putty knife until you get a uniform consistency.

Step 2: Spread the filler over the wood

Spread the filler over the wood as quickly as you can. Be careful not to put on more than required because wood fillers dry up fast, especially petroleum-based fillers, as sanding off the excess may prove difficult. Apply wood fillers only a small portion at first; then, you can apply more if it shrinks to some extent as it dries.

Step 3: Push the filler into cracks in wood

Press the wood filler deeply into the cracks; you can use your fingers. After which, you clean off the surplus filler from the wood. Also, wipe your finger with a dry cloth to get rid of the filler. Water or mineral spirits will also be useful in removing any leftover residue.

Step 4: Allow to harden and sand

Allow the filler to harden for roughly one hour. Sand the wood filler into a smooth surface using an oscillating sander first and then sandpaper. Use a tack cloth to clean off the dust residue from sanding. If you have a lot of dust residue, you might need a shop vacuum.

After these, you can coat and shine the patched area. Remember to stain the area to even the color differences.

How to Use Grain Filler?

Here’s how to use a grain filler;

Applying a grain filler isn’t so difficult. You need to get the color of the filler right. Else, it will leave apparent damage. For this, you need a trowel/brush, sandpaper, a piece of burlap and the grain filler.

Before applying the grain filler, sand off the surface and spread over some putty, if you slather on the grain filler without concealing the defects in the wood, it would only make them more noticeable.

Spread on the filler with a brush or trowel and wipe off the excess. Please leave it to harden for 30 minutes or, better yet, an hour. Then, sand it down to get an even surface. This works generally, but some fillers require unique applications. In such cases, adhere to the instructions on the label.

The Best Wood Filler and Grain Filler to Buy

When buying wood and grain fillers, go for products that help you realize that final clear finish depth and glossy shine. We recommend the Aqua Coat Wood Grain Filler and the Gork’s Goodfilla Water-based Wood Filler.

Aqua Coat Wood Grain Filler provides a solid advantage; beginners and seasoned contractors can use it. It adds depth and guarantees a mirror-like finish. It is quite stress-free and durable too.

Also, choosing Gork’s Goodfilla Water-based Wood Filler means quality at a fair price. This wood filler accepts stains and finishes nicely. You can easily sand, plane, paint, stain, or lacquer it. It is designed to provide a terrific working experience for both the experienced artisan and the DIYer.

Final Thoughts

Wood finishing is an all-or-nothing step in woodworking projects. It’s that one place where you either hit or miss. One way to get it right is to apply fillers where necessary. Use wood fillers if you need to fix blemishes in your wood like a major crack. If you want to even the wood surface and get that glass-like shine, you need a grain filler.

Martin Swizz

Hi! This is Martin, I like to research, experiment, and learn new things related to wood carving and other kinds of woodworking.

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