Sawdust/Epoxy Mix for Filler

[Randy Heinemann]

I am making a couple of natural edge tables. The tops are walnut slices; so end grain. I need to secure a couple of checks with epoxy. In the past, I've used dye concentrate to color the epoxy, but recently saw some work done where the creator used sawdust from the sanding operation of the wood mixed with epoxy. It seemed to be a better option from the standpoint of appearance. However, I don't know the specifics of proportions of epoxy versus sawdust.

Has anyone done this?
How much sawdust is needed to color the epoxy?
Could I add too much sawdust and interfere with the strength or curing of the epoxy?

Generating the sawdust is also kind of a big job? I can collect it with a sander with on-board dust collection but, in my tests, sanding doesn't seem to yield very much in the collection bag.

For anyone who has tried this, your input would be very helpful.

[Cary Falk]

I have never had any luck getting a match to my liking with sawdust and glue.

[al ladd]

I use a hand held belt sander with a cloth collection bag. My sander is a Ryobi form 1983 and it's the only thing I've used it for for over 30 years. I can generate enough dust to fill a film canister (remember those?) in a few minutes. Take the bag off and shake it out over newspaper, and funnel into your container. 120 grit works well.... Add as much as you can to the epoxy , mixing it in well. Also works well to fill crack packed with dust and saturate with CA. Fill will always come out darker than the wood it was made from, so you might cheat that a bit by selecting , for walnut, a board of mostly steamed sapwood.

[Richard Coers]

Keep in mind that cookies never stop moving. They shrink and swell every winter and every summer. For coloring epoxy to fill small knot holes, I use epoxy and dried used coffee grounds. The filler has a variegated color and doesn't look like plastic. As with any new process, please practice on a piece of scrap. Too many questions about how to I fix this color.

[Randy Heinemann]

Keep in mind that cookies never stop moving. They shrink and swell every winter and every summer. For coloring epoxy to fill small knot holes, I use epoxy and dried used coffee grounds. The filler has a variegated color and doesn't look like plastic. As with any new process, please practice on a piece of scrap. Too many questions about how to I fix this color.

Wood never stops moving. I believe that is the point of filling the cracks on a cookie that may travel far enough for the piece to break. Some of the imperfections I wouldn't touch but there are a few cracks that are all the way through and might travel to the edges.

[Doug Garson]

Wood never stops moving. I believe that is the point of filling the cracks on a cookie that may travel far enough for the piece to break. Some of the imperfections I wouldn't touch but there are a few cracks that are all the way through and might travel to the edges.
For cracks like you describe I would recommend adding bowties to stabilize the cracks, epoxy won't necessarily hold a crack together.

[Michael Rutman]

I had a friend come over to show me how to do it, we used the bandsaw to get the sawdust, worked great, just turn off the dust collection.

After filling and when it was still a bit unset, she pulled out some very small saws and started adding wood grain patterns to the epoxy. Took quite a while. After we were done, she said if it was her project she'd have left 1/8" gap and finished it with putty. Looks better and stains correctly.

[Randy Heinemann]

Wood never stops moving. I believe that is the point of filling the cracks on a cookie that may travel far enough for the piece to break. Some of the imperfections I wouldn't touch but there are a few cracks that are all the way through and might travel to the edges.

The place I bought the pieces from is the expert. He does this professionally and has for years. He didn't recommend bowties for any of the cracks because of grain direction. He said, from his experience, they wouldn't hold. There are, in fact, only about 4 or so cracks in the two together which he recommended stabilizing with epoxy. He uses sawdust of the same type of wood that the pieces are from; in this case walnut. Since I bought the pieces flattened, the only thing left is some sanding. Using a belt sander would ruin a perfect flattening job. So, right now, I've decided to look in my lumber and turning blank stock to see if I can find a piece that is close to the same color as the two I am prepping; then use a belt sander on that piece to create enough sawdust for the fills. There is also a knot which I may fill in on one side to make sure it doesn't loosen up and this is very dark (almost black), so I might use coffee grounds for that one or some dark powdered dye. Currently I have System Three epoxy which may be sufficient for all of the work. Also, after contacting System Three, they indicated that, for larger cracks and fills, their Mirror Cast is a better choice. It takes longer to cure but doesn't generate as much heat when curing, which apparently can cause some discoloration. However, if I did a couple of partial fills, then their General Purpose would be fine as long as I wait between layers. So, I will experiment with what I have on some other walnut and see what happens. They are tables for my daughter so I want them to look as professional and as good as possible. Thanks for some recommendations. I've heard them all and threw in other information, but it was all useful.