What does grain filling do??

[Toller]

I am reading "Finishes & Finishing Techniques" by Fine Woodworking. They recommend using a grain filler for oak, and suggests dark to emphasis the grain.

So I bought some Behlen's Water-based brown grain filler, sanded, applied, and sanded again per directions on one half of a piece of red oak. I then put on some Spainish Oak stain and two coats of poly on the whole piece.

The grain is more striking on the treated side, and they seem to reflect light differently, but that is about it. They don't feel any different, or look all that much different. In fact, I kinda like the unfilled more; it is subtler with more variation in the grain coloring. I think the neutral would be nearly identical.

So... what is the difference supposed to be? What I observed, or did I screw up somehow and it is supposed to be completely different? Thanks.

[Frank McVey]

Hi, Toller.

Grain Filler should do exactly what it says - it fills the pores and, properly applied and cut back, should leave a perfectly smooth surface for subsequent finishes. You can do without it and simply rely on successive coats of your finish and cutting back to fill the grain, but grain filler makes the process go more quickly. It's used a lot in french polishing where you want to build up to a mirror finish. Shellac "sinks" a lot, so it would take many coats to fill the grain if filler wasn't used.

It can also be used to give different colour effects to the wood - limed oak is an example of this.

It's very easy to drag it back out of the pores if you're heavy handed when applying it, and this may what has happened to your piece Apply it quite thickly *across* the grain, to minimise this. Even with this precaution, it's sometimes necessary to go back over the piece with the filler again if it has large, coarse pores, like oak. Fine-pored stuff like mahogany only usually needs one application

I'm like you - I prefer to see the texture of the wood.

HTH

Frank

[JGS]