Wood Grain Filler for Guitar Bodies

All hardwoods are fairly open grained, some more than others. To achieve a smooth glossy finish we really need an even surface to work with and when using an open grain timber such as Mahogany this can be difficult. To achieve this the open pores should be filled using a wood grain filler. It’s not a difficult job but there are a few basic steps to keep in mind which we will outline below.

Timbermate Wood Grain Filler

Timbermate Wood Grain Filler is a good option.

What is Wood Grain Filler?

Grain filler is made up of three basic ingredients. Firstly there is the binder which is acrylic in water based grain fillers. Silica as a bulking agent (ideal because it wont shrink depending on the temperature of your work environment) and the solvent which in water based grain fillers is obviously water.

Grain filler is not to be mistaken with timber putty. Although handy to have around when working on kit guitars, putty is better suited to repair work due to it’s density compared to grain filler. For example fixing a heavy mark or a poorly placed screw hole.

What Grain Filler Should You Use?

It comes down to what you prefer to work with but it’s not a bad idea to stick with water based grain filler as it’s less messy and dries quickly. Water based products have come such a long way in recent times that it really makes little difference choosing water based or oil based fillers, paints and stains for the most part.

You can generally purchase grain filler in clear or tinted variations. You can also add a water based pigment to achieve the color you prefer. It’s best not to overdo things though as you can effect the drying time if you use too much. If in doubt use no more than 10%-15% pigment.

Another great advantage to using a water based grain filler is you can still stain the guitar after you have applied it. All grain filler will have an impact on the surface color of your guitar body so this allows for a more controlled staining option if done after the grain filler is applied.

Grain Filler Application

If you do require a grain filler to be applied first mix up a batch in a separate container. Start by adding about 10% water straight to the container. Grain filler doesn’t have a use by date so you can simply seal the container leaving the excess you didn’t require. To re-use at a later date you simply add more water. Once mixed into a paste you can simply apply with a rag. You can also brush it on or use a scraping tool but a rag also works well. You will need to really work it into the timber to achieve a good result. Do this by first rubbing firmly with the grain and lastly rubbing against it to really work the grain filler into the timber pores.

Once you have worked enough grain filler into the timber you can start to scrape away any excess. Be sure to scrape the filler away quickly as waterbase grain filler dries very quickly once not being worked with the rag and dries hard, meaning you are going to raise a sweat if sanding too much excess of by hand. Once done, you can begin sanding the surface to get that glossy, smooth look perfect for applying a paint or stain to.

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13 Responses to Wood Grain Filler for Guitar Bodies

  1. Gino January 25, 2016 at 10:01 pm #

    Dear Marty

    Thanks for your blog entry about this.

    I just want to be 100% sure I’m doing it right:

    1. Sand off my mahogany body with maple top
    2. apply the wood filler on the mahogany parts and work it in
    3. paint the whole guitar
    4. apply the lack

    Is this the way it should be done?
    Thanks for answering!


    • Marty January 26, 2016 at 2:36 am #

      Hi Gino

      Thanks for getting in touch.
      That is pretty much the process to follow.

      Just be sure to get the ratio of grain filler to water correct (10-15%) and really work it into the timber, moving in one direction then across the grain in the opposite direction. I’d also recommend then wiping away as much excess as possible before it dries as it does take some time to sand if you have excess to remove.

      With a loosr grained timber like Mahogany I’d do this twice before proceeding.

      Once complete, sand back to a nice even finish using 320 grit or higher gauge sandpaper. (You may need to start with a rougher paper at first but work your way back to 360 before moving on). You should then be able to finish the guitar.

      I generally recommend Timbermate grain filler, there’s more information available here:

      Hope that helps Gino

  2. Julian Klazinga March 10, 2016 at 5:26 pm #

    Ive read some places that the filler should be applied after the stain, is this correct?

  3. Robbie March 13, 2016 at 4:00 am #

    I’m glad I stumbled on this site because I am completely confused on some issues! (Too much web reading). I have an ash guitar that I’m building. Bought the timber mate product (neutral). I first sanded as suggested, used the timber mate, sanded, then applied a stain. Now I’m at the confusing part. I’ve read you now use a sanding sealer, followed by coats of lacquer. Is the sanding sealer necessary? If so, I’m confused on what to use. I purchased minwax sanding sealer, but it says to use polyeurothane after sanding sealer.

    So do I need sanding sealer, or did the timber mate take care of that? I’ve also read that you should “wash” the product with a mixture of lacquer/thinner in order to “seal” the timber mate into the pores. So much to this! I’ve completely confused myself!

    • Marty March 13, 2016 at 8:17 am #

      Hi Robbie

      Thanks for your question. There’s many different ways to go about finishing a guitar so don’t feel compelled to follow any one specific method.
      In answer to your question, no you don’t specifically need to use a sanding sealer. There’s no problem with doing so but you can avoid this step and move straight onto your top coat after staining. Hope that helps Robbie.

  4. Mel June 21, 2016 at 12:13 pm #


    If I want to achieve a natural finish, with just staining, would I still need to do this grain filler step? Thanks for your help .


    • Marty June 21, 2016 at 9:08 pm #

      Hi Mel

      Thanks for your question. I guess the first thing to ask is are you using a timber that requires grain filling? e.g. you only need to do this for open grained timbers e.g. Mahogany.
      With that in mind, you can really do it either way around, my preference is to use a tinted grain filler (if the available tints are within the color range I am looking for at the time) as this effectively kills two birds with one stone. Alternatively, I would grain fill first and stain second. If staining first definitely test your mix on a scrap piece of timber first. Hope that helps.

  5. Mel June 22, 2016 at 11:29 am #

    Hi Marty,

    Thanks so much. What would you recommend, a water based or oil based filler, for a mahogany body ?


    • Marty June 22, 2016 at 9:29 pm #

      Hi Mel, personally I prefer water based, it’s easier to work with. Hope that helps.

  6. Mel June 23, 2016 at 1:50 am #

    Hi Marty,

    Thank you so much for all your help. Appreciate it.


  7. Asif Abbasi July 20, 2016 at 9:58 pm #

    Really glad I found this side. I have crack on my guitar’s (PRS) headstock. The headstock is Mahogany finish. As there are no luthiers or any reapair shop here. I have to fix it myself. So I’m a total beginner about all this. From all the information I gathered from internet I’m thinking
    I should sand the crack a little. Fill it up with grain filler (mahogany colored). Sand it. Use Tru Oil over it. Put a few layers of it. Sand it. Put lacquer on. Wet sand it and buff it.
    Not sure if I should go with wood filler or grain filler? Please help me through this and guide me what products to get for this job.

    • Marty July 21, 2016 at 1:06 am #

      Hi Asif

      Thanks for your question.

      How bad is the crack? If you need to actually repair a deep crack in your headstock I’d firstly fill the crack with carpenters glue (something quite strong) to handle the tension on the headstock. You should then clamp the neck tightly, but be sure to protect your guitar’s surface form the points of the clamp. (I know that’s fairly obvious..but you would be surprised how many people forget to do this).

      When it comes to filling the crack after it has been glued. Grain filler is really more for creating an even surface for finishing. I’d suggest using a timber putty, something along the lines of: https://www.bunnings.com.au/timbermate-250g-mahogany-wood-filler_p1560669

      You would then need to find a finishing product that matches your current finish.

      Hope that helps Asif.

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