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