Introduction: Virtually Invisible Wood Putty for Any Species of Wood - Free!

OK, I confess - I'm a perfectionist. If you don't believe me just ask my wife. To me, there are few things worse than completing a wood project and having gaps in joints or noticeable circles where a hole was filled with wood putty. The colors never seem to quite match and - even if they do - the commercial wood putties don't seem to take a stain or finish the way they claim to. There is a simple and essentially free solution however - make your own wood putty as needed and specifically for the wood you are using. Here's how.

Step 1: Kick Up a Little Dust

You'll need a scrap piece of the wood you want to repair. For the example shown I'm using walnut. You'll also need a scroll saw, a fine-toothed Japanese style saw, a sander, or some other method of producing very fine sawdust. For my example I used a scroll saw. Clean the table of the saw so there is no dust on it. Then cut several strips of wood - it's the sawdust that's important here - not the wood (see Figure 1). Be sure to turn your air jet (if your saw has one) away from your work so you're not blowing the dust away as you create it. Once you have a satisfactory little pile of sawdust, scrape it all together with a piece of paper (Figure 2) and funnel it into an old prescription bottle or something like that (Figure 3). Label the bottle with the species of wood. Helpful note: When I'm working with a particular species of wood I do this as a routine. I've built up a little library of prescription bottles with labels on them - walnut, bloodwood, cherry, etc. Then I just pull out the bottle I need at any given time.

Step 2: Mix Your Putty

In Figure 4 you'll notice the gaps along the joint where I've glued two pieces of walnut together. This is what we're going to fix. Pour out a little pile of the sawdust onto an expendable surface such as a piece of paper. Use a toothpick or slender scrap of wood to form a hole in the center like a volcano (you do this because when you add the glue it tends to roll right off the sawdust).

Step 3: Mix Your Putty Continued

Squeeze a little carpenter's glue into the caldera (aren't we using fancy words?) of the volcano (as in Figure 5) and use the toothpick to mix it with your sawdust until your mixture is about half glue and half wood (Figure 6). Mix and squish until you can no longer see the glue separately from the sawdust. You can pour the remaining loose sawdust back into your bottle for future use.

Step 4: Applying the Putty

Work the glue/sawdust mixture into the flaw you want to repair. Mound it over the top a bit to allow for shrinkage as the glue dries. Figure 7 is from another repair on the same wood.

Step 5: Sand and Finish

Once the glue has dried, sand the repaired piece smooth - and there you have it. Can you see the repair in Figure 8? Hard to spot, isn't it? And even harder after a finish of Danish Oil is applied (Figure 9). And please bear in mind that these photographs are all extreme closeups. Since this repair is about half wood, it will take stain and finish just like the surrounding wood. If you want to prove to everyone that you're truly OCD, you can do the sawdust collection process while you're working on any given project - the color of any species of wood will vary from one board to another, and by using sawdust from the piece you're actually building, the color of the sawdust you're using for the repair will exactly match the wood.

Thanks for taking a look at my Instructable. I hope it's been helpful, and

Peace,

Radical Geezer

Comments

author
Hashem_Mehyar (author)2016-02-05

The thing is, the fix will become clear as day when painting it, because the wood would absorb the dye or varnish, and the glue wouldn't .

author

Some more specific information from my own experience, Hashem. This fix on darker woods has not presented any absorption/matching problems at all. On lighter woods, it may turn out that the raw fix will be just a wee bit darker than the surrounding wood because the glue portion of the fix tends to dry a bit darker. You could experiment with different types of carpenter's glue I suppose, and Sixsmith (below) has recommended epoxy, which I haven't tried. But if you're finishing with oil or some sort of varnish, these tend to darken the wood slightly anyway, so the fix becomes even less noticeable. The only case I can think of where the fix may not essentially disappear is with a very light wood and a polyurethane finish. The fix may be a bit darker than the surrounding wood and polyurethanes are water clear - they do not darken the wood at all. So if there is any degree of difference of color in the raw fix, that difference will probably remain in the finished piece. But the point is that I haven't come across any other method of repairing a flaw that will come as close to a perfect match as this one does.

author

Try mixing the sawdust with flour, and then use water to make a paste. This has roughly the same absorbtive qualities as the wood itself.

author

that's new! I'll try that

author
Radical Geezer made it! (author)Hashem_Mehyar2016-02-05

That's not the case, Hashem. If you've mixed it properly - so that it's at least half sawdust - the fix has virtually the same absorption qualities as the surrounding wood. I'm including a picture of the same joint I made in the article but a day later. The Danish oil has been absorbed and I promise you I did nothing else to it - didn't even wipe a cloth over it. Can you see any difference between the fix and the wood in terms of how the oil has been absorbed?

walnut joint.jpg
author

Hell no! OK then, I guess I've got the ratio wrong, great work, and from you I learn.

author
rwilliams22 (author)2016-02-07

This is a good tip, but I can suggest a modification which may improve it. Wood glue resists certain finishes. If you mix the fine sawdust half-and-half with flour (not self-rising flour), and add a bit of water, you have a mixture that will take a stain or varnish as well as the surrounding wood.

I learned this from a friend who built boats, and he used a mixture of sawdust and flour to rub down the boats before varnishing. After rubbing with the mixture, he would remove the dust with a wet rag. Any of the mixture that was embedded in a crack would then be glued in place. In case of a small leak, the flour and water mixture would swell up, sealing the spot.

author

Sawdust and flour? Now that's an intriguing idea - I'm going to have to try it. My guess is that it would also produce a great color match even on lighter woods. I'm glad I started this conversation - I'm learning as much as I'm sharing. I'm also thinking that if you're working with smaller projects rather than something as big as a boat and you want to wind up with a really smooth surface, you'd want to make a paste with the flour and sawdust by mixing in a bit of water before you applied it, over-fill, let dry, then sand smooth. The only problem I can see is if you're making something that's not going to have any finish at all...just natural raw wood. In that case a sawdust/flour fix probably wouldn't hold up over time. But a truly outstanding outside-the-box idea - Thanks!

author
Wood Chuck (author)2016-02-06

I have used this method for years and yes it works very well. Another alternative is to use thin CA glue (superglue). I also find the white glue instead of yellow glue doesn't leave the dark glue mark. Thanks for posting

author
oldcarnutjag (author)2016-02-06

thank you I now have a use for old film cans.

author
JACK G (author)2016-02-06

Jack

Filling cracks with a glue and saw dust mixture is not successfull when light coloured woods are used.The glue leaves a darker line. I use a light clear glue used for repairing veneer is a closer match when finshing.

author
sixsmith (author)2016-02-04

if I'm using a power sander to finish my projects I like to clean out the dust collector bag before I switch to 220, then I use that collected saw dust in the same manner as you, though, I personally find epoxy a bit easier to work with compared to wood glue, but it does cost quite a bit more.

author
chrisagnew (author)sixsmith2016-02-06

this is my exact method, works well. right out of the sander and mix with a little epoxy. if i am getting really serious, can add trans tint to the epoxy to darken it a little

author
chrisagnew (author)sixsmith2016-02-06

this is my exact method, works well. right out of the sander and mix with a little epoxy. if i am getting really serious, can add trans tint to the epoxy to darken it a little

author
Radical Geezer (author)sixsmith2016-02-04

That's an excellent idea for collecting sawdust. I would worry a bit about the quick dry time of epoxy and whether it would take stain as well, but it's certainly an idea that deserves consideration. Thanks!

author
sixsmith (author)Radical Geezer2016-02-04

Epoxies come in all sorts of cure times, I am generally good with the 15 minute time, unless I've got a lot to do. the only thing is epoxy is pretty hard so I always scrape the joint while it's wet with a razor blade so the epoxy is dead level with the rest of the wood.

author
Jobar007 (author)2016-02-05

Personally, I always use the saw dust from sanding the board. I'm like you in the regard to perfection. That's why I don't store any saw dust. The difference between different boards of the same species is too great for my OCD nature.

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Bio: Vietnam era veteran (USAF), former air traffic controller, former entrepreneur, former clergy, former chauffeur. Currently retired and busier than ever. Devoted husband to an extremely ... More »
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