# mixing sawdust and glue as filler



## TungOil (Jan 16, 2017)

for those that mix sawdust and glue to make matching wood filler-

- what glue do you use?

- how best to mix it?

- doe it take stain and finish like the surrounding wood?


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## JBrow (Nov 18, 2015)

TungOil,

I routinely mix yellow wood glue with fine sanding dust to fill surface blemishes and have done so for several years. I have thought about experimenting with white wood glue for a better color match, but have not done so. I collect sanding dust from the dust collection canisters on the Porter Cable random orbital sanders and keep walnut and red oak (woods with which I mostly work) dust in containers for this purpose.

I have taken two approaches to using wood glue and dust to fill in imperfections. Both seem to work equally. Whether these methods work well or bad I guess is a matter of personal opinion, but I prefer this type of filler to clear-curing epoxy, commercial wood filler, and waxy post-finish fillers.

In the first method, I apply wood glue to the defect and then press sanding dust (from the wood being repaired) into the glue.

In the second method I mix the sanding dust with wood glue to a consistency of a little thinner than that of peanut butter. I mix by squeezing a dollop of wood glue onto a smooth piece of scrap wood. I then slowly sprinkler sanding dust over the glue and stir. I continue adding dust until I have obtained the consistency that allows me to transfer and press the glue-dust mixture to the defect. The mixture is lightly sprinkled with sanding dust before pressed into place. The light sprinkle reduces the extent to which the mixture sticks to my fingers. Sometimes I have used a putty knife to screed the filler, but if the mixture is too thick, the putty knife can lift the filler from the defect. The "open-time" with this method is fairly short (maybe 10 minutes).

I find that once the glue-dust mixed has cured, a second or third application is required to build the glue-dust mixture proud of the surface. Once the glue is cured, the surface is sanded flush. I try to fill the defect just before sanding to final grit. For example, if my final grit is 180, the filler is applied after sanding to 150 grit. The cured filler is sanded flush with 150 grit and the entire workpiece sanded to final grit.

I tend not to stain my projects; I generally apply a clear film finish (oil-based urethane or polyurethane). The repaired area tends to be darker than the surrounding area and seems to take the finish well. The filled defect on a finished project produces an interesting affect. The defect invites a touch. It is a surprise when the defect (darker area) is found to be flush with the surface; something that is unexpected.


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## waho6o9 (May 6, 2011)

JBrow for the win!


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## TungOil (Jan 16, 2017)

Thanks Jbrow. You method number 2 is exactly what I'm experimenting with tonight on some scraps. I also picked up some Famowood which is my usual go to for filler. I need to do some finish test samples anyway so I'll see how they come out.


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## 000 (Dec 9, 2015)

If I'm doing something that has a natural finish I will mix up some using white glue. 
If I'm doing something to be stained I won't make my own, I normally use Famowood filler. 
(same as TungOil)


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## Carloz (Oct 12, 2016)

Dont do it. When you apply stain you will see why.


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## RichT (Oct 14, 2016)

For minor fills, I have used the Dave Marks technique of filling it with sawdust and dripping CA glue to set it. For the sawdust, I collect larger flakes from around the router table after raising panels, etc, and put them through a Krups spice and coffee grinder. I've also collected it from my sander dust bag. That is a very fine powder and is OK for very small imperfections in glue joints, but for anything on the surface, I prefer the slightly coarser dust from the grinder. I find the coarser powder stains more naturally since it is more porous. Neither will be invisible after finishing, but with a wood like knotty alder, it's difficult to distinguish the repairs versus the natural features of the wood.

Given the type of fine furniture you are building, it's hard to picture that sort of repair being acceptable. It's going to stand out I'm afraid.

I know you specifically asked about glue and sawdust fill, but what I've been working with lately are the various types of burn in sticks from Mohawk. It's intended to be used on finished wood, so the repair is done after finishing. There are dozens of colors, and they can be mixed to create just about any color you need.

In between projects, I like to try to improve my finishing techniques and learn new ones on test boards. I've had very good results with the sticks so far, to the point where I have difficulty finding the repair even on small sample pieces that I've finished, gouged and repaired.

Before springing for a dedicated hot knife, I attached a piece of 0.015" feeler gauge to a soldering iron to test the sticks. It works pretty well. I also picked up some pallet knives at the art store and can use them with a heat gun for a surface to blend on.

Right now, I don't really picture doing glue and sawdust fills in the future, since this is working out to be easier and the results are outstanding.

There are videos on the Mohawk site for more info. I'm still in the learning stages, so I'm not ready to offer any definitive guidance.


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## TungOil (Jan 16, 2017)

Rich- I hadn't thought of using burn-in sticks, I'll look into them as an option as well.

This is what I'm trying to resolve-










It's a very small gap, about 1/64". Unfortunately it's in a very visible space on the top and outside edge of a table top I'm working on. Any other ideas on how to fix this are welcome.


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## josephf (Aug 29, 2012)

wait end grain . i would think that this is not going to be easy . i do not know what your building or the detail . If this was a kitchen cabinet I was building i might rub a similar colored caulk in the gap and walk away . if this is a "piece" I might change the detail ,maybe add a dutchmen or a wedge of wood following the line of the joint . 
there is always "call it good" 
what needs to happen is to get the black line to go away .then it generally will not be seen .
ahh -I feel your frustration .been there . alot easier to swallow when it happens years down the line .
that hot wax idea might work here .be a good repair method to have in the shop .has to be something that has give .far better to have a crack in the joint then cracked filler .


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## rwe2156 (May 7, 2014)

> This is what I m trying to resolve-
> 
> 
> 
> ...


You will have a very difficult time getting that to disappear.

I would abandon any though of glue/sawdust (I never do it because it looks awful) and either insert a sliver of wood using epoxy or CA

I'm a big fan of "happy accidents" ala Bob Ross so consider accenting with an inlay.


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## josephf (Aug 29, 2012)

Well said


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## bondogaposis (Dec 18, 2011)

I prefer to use sawdust and hide glue. I think it blends in with most finishes better.


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## TungOil (Jan 16, 2017)

I will experiment with cutting a sliver to fit. It might be hard to cut a 1/64" sliver of wood to fit in there…..


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## RichT (Oct 14, 2016)

> I will experiment with cutting a sliver to fit. It might be hard to cut a 1/64" sliver of wood to fit in there…..
> 
> - TungOil


The only problem with a sliver is that it's going to be long grain, and you're putting it in a cross grain opening. I see some test joints in your future, Tung


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## diverlloyd (Apr 25, 2013)

You can run a flush cut saw down the gap until the pieces fit together tight.


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## TungOil (Jan 16, 2017)

I'll try to cut the sliver end grain. I still have all the drop offs, I should be able to find the one that came from this piece easy enough.

Replacing it is not an option, unfortunately. Already glued on, would do more damage trying to remove it. The segments are all sequential/grain matched, a replacement would look out of place.

The photo is making it look worse than it really is, the gap is only about 1/64" or so. Some sort of filler is the likely fix and I'm sure I'm the only person that will ever notice it (well, and now all of you too!). But it still bugs my perfectionist side…..


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## OSU55 (Dec 14, 2012)

No filler of any kind takes color like the surrounding wood, and sawdust mixed with glue is the worst - the dust is fully saturated with glue and can't absorb color. Matching wood not to be colored, only top coated, is completely different - glue & sawdust are ok, as well as fill pieces etc. Depends a lot on the topcoat used. I add color to some degree for any project. I have recently been using Timbermate filler, and am finding it far better than the other fillers I've tried. Mixed with acrylic paint I find areas or grain cab be filled without color being absorbed ito surrounding wood. Test is required to get the correct shade after the piece is dyed/stained, but I've had great success.


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## ClammyBallz (Apr 16, 2015)

Would be nice to see the whole piece. You might be better off using a 1/8" router bit and adding an inlay to hide it.


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## dday (Jun 27, 2014)

I've never had success with the glue/sawdust filler. For that line you're trying to hide, if recutting the joint and joining it cleaner isn't an option.. then I would cut a dado along the line and insert some accent wood, or even a piece of the same wood , turned with a different grain.. and if it's not in the middle of the piece, create a symetrical matching accent also.

Fancy "accents" can hide a multitude of sins…


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## TungOil (Jan 16, 2017)

> Would be nice to see the whole piece. You might be better off using a 1/8" router bit and adding an inlay to hide it.
> 
> - ClammyBallz












the joint in question is near the 6" rule


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## OSU55 (Dec 14, 2012)

What is your planned finish schedule? Stain/dye and color? Topcoats? Etc. any inlay etc would need to be repeated at each joint to look the best. With some color, and especially with a darker glaze, it could be blended in using filler.


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## Carloz (Oct 12, 2016)

> the joint in question is near the 6" rule
> 
> - TungOil


1/64" gap is the least of your problems. The wood expansion/shrinking of the perpendicular (almost) grain direction will make much bigger gaps and cracks in unexpected places. 
Unless there is something I do not see here.


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## TungOil (Jan 16, 2017)

> What is your planned finish schedule? Stain/dye and color? Topcoats? Etc. any inlay etc would need to be repeated at each joint to look the best. With some color, and especially with a darker glaze, it could be blended in using filler.
> 
> - OSU55


Working that out right now, I have some sample panels prepped to try out several topcoat options. each will have half of the panel stained with the Darrell Peart formula: General Finishes dye stain mixed 7 parts orange to 4 parts med. brown. Other half will be natural.

I punched a few holes in one test panel and filled half with Famowood Mahogany, other half with sawdust I collected from the drum sander when I made the veneers for the tops mixed with some white glue. Hopefully one of those will do the trick. I have two coats of stain applied so far and at this point, without any topcoat applied, the white glue + sawdust is winning hands down.


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## TungOil (Jan 16, 2017)

> 1/64" gap is the least of your problems. The wood expansion/shrinking of the perpendicular (almost) grain direction will make much bigger gaps and cracks in unexpected places.
> Unless there is something I do not see here.
> 
> - Carloz


Indeed, good thing it's shop sawn veneer over Baltic Birch plywood cores!


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## TungOil (Jan 16, 2017)

Here are my samples so far. I plan to test both stained and no stain- this is the stain test sample. I punched two pairs of holes about 1/8" diameter with an awl, then filled the left hole with Famowood Mahogany and the right hole with a paste made from Elmers white glue mixed with sanding dust to a peanut butter consistency. The Famowood sample is just below the tip of the steel rule and the sawdust/Elmers is below the tip of the pencil. Without any finish, the sawdust is a much better match, but that is not surprising since the sawdust came from sanding the veneer.










I then applied 3 coats of General Finishes dye stain, but no top coat yet. Depending on what angle I look at the sample, the repairs either blend perfectly or are quite visible. From this angle, the Famowood looks too light and the sawdust is a near perfect match.










From this slightly different angle, the sawdust looks too dark and the Famowood is a good color match.










looking at it in person, I think the sawdust mix is the closer match so far. We'll see if that changes after I apply the topcoat.


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## JBrow (Nov 18, 2015)

TungOil,

After seeing the problem, considering insertion of a shim to fill the gap might be a better way to go. Picking up on what I understand to be diverlloyd's suggestion, a handsaw could be used to cut the gap in the table edge banding joint wide enough so that a shim could be glued into the saw kerf. If the shim matches well to one or the other side of the joint and the joints are tight, the repair would likely disappear completely.

The biggest problem with this approach would be ensuring the handsaw cut is true and straight in the vertical and horizontal directions. If this approach is taken, then obviously a well thought out setup would be required to guide the saw and produce that straight cut.

Since you are looking for a crack filler, it may be helpful to evaluate the glue-dust and Famowood options on a some practice cracks rather than on a divot. Potential problems could arise when trying the pack the crack with sufficient filler. If such difficulties exist, these problems could be flushed out by practice-filling a crack.

Two pieces of scrap wood could be screwed to a backer piece of plywood with the ends butted together while leaving a slight gap. The butted ends of the scrap pieces could be spaced apart with a sheet of paper inserted between the blocks to produce that narrow gap. Once the blocks are screwed in the place, removing the paper spacer would reveal the practice crack. Then the two methods could be tried.


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## wormil (Nov 19, 2011)

I have a suggestion. Whatever method you use is going to show so rather than try to get an impossibly perfect match I would go another way. Glue a shim in place and make it slightly darker than the wood, fill and smooth any cracks so you can't feel it. After staining and after your seal coat, take a dry brush dipped in stain and rub your finger across the bristles creating a spatter effect around the repair. (Goes without saying that you'd want to practice on scrap first). The random spattering will make it more difficult for the eye to focus on any one spot (camouflage). Commercial furniture finishers use a similar technique to hide flaws. You can also do it between layers of finish.


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## JAAune (Jan 22, 2012)

> I know you specifically asked about glue and sawdust fill, but what I ve been working with lately are the various types of burn in sticks from Mohawk. It s intended to be used on finished wood, so the repair is done after finishing. There are dozens of colors, and they can be mixed to create just about any color you need.
> 
> - RichTaylor


If I can't add a real wood repair, I too, always do touch ups after applying the first coat of finish. It's the only way to ensure a perfect color and grain match.


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## TungOil (Jan 16, 2017)

Thanks to everyone for the many good suggestions. I'm going to continue to tinker with different ways to tackle this. I have plenty of scraps in the bin to work with and I just picked up some walnut Famowood to test. I have some segments glued up to simulate the 1/64" gap I'm trying to deal with.

In the end, it's just 1/64", really not much anyway.


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## Finn (May 26, 2010)

I do a lot of filling in slight gaps while doing inlay. I use white glue and sanding powder of the wood in the project. (saw dust is way to coarse)
Using yellow glue will darken the filler a bit. I apply this filler, which I mix to the consistency of mayonnaise, with a credit card used as a squeegee. Allow to dry 20 minutes and sand off well. Clear finish will work well if the voids are very narrow. 1/16" or less. Stain will not work well with this filler. Any filler mix that is not sanded off completely will look cloudy under clear finish like Lacquer or Poly. You can test, this before applying finish, by wiping mineral spirits on the project and any problem will show up immediately.


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