I’m working on a small project (epoxy coasters) but every so often I keep getting these weird marks. Sometimes they are as deep as shown, other times they are smooth but more white-ish dull marks.
Does anyone know what is causing these marks and how can i remove them?
The board is a .75" aromatic cedar, planed down to .4"
Also if anyone has a good method of sanding the side of coasters…I’m interested!
It’s called ‘tear-out’, and what’s happening is that the wood isn’t cutting, the blades are ‘ripping’ the wood from the surface.
Sometimes the direction of the grain of the wood means that this is almost inevitable no matter what you do. If you can, check the sharpness of the tool you are using, tear-out definitely gets worse as the tool dulls.
If this is off a planer, often running the wood through in the reverse direction can make a difference. However, sometimes that difference is just that this section gets better, but a different section of wood gets worse. For example, around a knot the tearout will typically just move from one side of the knot to the other.
Taking an extremely shallow final cut may also help.
It seems to me to be worse in softwoods, but hardwoods are not immune - I frequently see it in Birch around knots, for example.
An idiots take. I know that hard wood has close rings. Soft wood has wide rings interspaced due to how it grows. Cutting a log the wrong way will open the rings another direction. Quarter sawn, Half sawn… I am still learning
Looks like the soft wood is being torn out by the cutter.
This is grain tear out. The grain runs in multiple directions and can chip out when cutting. Make sure your tool is sharp. You can try various things like Dewaxed Shellac (Zinnser Universal Sanding Sealer) to harden up the wood or the Minwax wood stabalizer. Both of these products are applied and allowed to dry (short time). They help make the wood surface harder and less likely to chip out. Those wide cathedral arches are very soft wood. The darker rings are harder but can still chip out. You commonly see this on highly figured woods when run through a planner. The fibers are unsupported and the cutting tool lifts the grain up and it tears out making the exact pattern you see in your picture.
If the material is already torn out you can try grain fillers. Fill the torn out parts with grain filler, let dry and then sand flat. Unfortunately it is the nature of wood to chip out.
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