What Does Interlocked Grain Mean in Woodworking?

In interlocked-grain wood, the grain has a pattern whereby the fibers twist initially in one direction and then switch direction for the following growth rings and continue this cycle as the years pass. Instead of growing in the same direction along the length of the board, the fibers move in a weaving way, and this creates a shimmering pattern once the lumber is either quartersawn or planed. Bubinga, Sapele, African mahogany, and Padauk are some of the exotic hardwoods that are commonly associated with interlocked grain as they are important to luthiers and woodturners because of their beauty; however, different grain orientation requires a different approach to using the tools.

What Is Interlocked Grain in Wood?

Interlocked grain is a description of wood fibers that do not follow the same directional pattern all the way down the length of the board. The wood fibers twist in a clockwise direction through a section of annual rings and twist in the opposite/direct, counter-clockwise direction next. The cycle continues this way as the wood grows. The analogy to keep in mind is that of loosely braided rope as opposed to one made of parallel strands. The log having this grain structure has its planks sawed in such a manner that opposite bands (those with the interlocked pattern) cause the ribbon stripe illusion that characterizes such wood types as Sapele and Bubinga.

Why Does Interlocked Grain Form?

The property of interlocked grain is primarily an inherent genetic characteristic of some tropical and African hardwoods, although environmental factors such as the wind, soil, and competition for canopy light may cause the extent of the interlock to vary between individual trees. The interlocking of grain is a constant feature of Bubinga, Sapele, African Mahogany, and Padauk. This is why these exotic woods are highly prized for their beauty in making furniture and as tone woods the same structure that causes the shimmer also provides a mechanical interlocking strength.

Which Exotic Hardwoods Show Interlocked Grain?

Not every interlocked-grain species behaves the same way at the workbench. The table below compares four of the most popular exotic woods carried at Exotic Wood Zone.

What Does Interlocked Grain Mean for Tonewoods and Guitar Building?

However, when it comes to luthiers, interlocked grain means more than just an interesting look. Reversing grain in Bubinga results in a very unique glassy sheen of Acoustic Guitar Set Backs and Sides that shifts depending on how light hits the wood, and in Sapele it's a tight ribbon that works great for Fingerboards and Headplates thanks to its uniform look after finishing. African Mahogany is a wood whose grain is mostly straight with some interlocked ribbon pattern here and there. This way it remains light and resonant while still providing a figure in case you get lucky. Padauk's interlocking tends to be subtler, but on quartersawn Bridge Blanks and Drop Tops it adds just enough chatoyance to complement its vivid orange-red color.

How Do You Work With Interlocked Grain Without Tear-Out?

The interlocked grain means that the cutting edge will be constantly following the grain in one place and going against the grain just a few millimeters away from there. It is exactly the reason for the tear-out to happen. There are several tricks that separate good results from bad.

• Always keep your blades, cutters, and plane irons super-sharp since any that aren’t will actually tear at the interlocked grain rather than slice through it.
• Use shallower cuts and reduce the feeding speed for the router table, planer, and jointer.
• Plane or scrape in short sections, reversing direction as the grain reverses; a card scraper or hand plane at a skewed angle helps a lot.
• When working on the lathe, perform light shear cuts rather than heavy roughing cuts when machining Bowl Blanks and Pepper Mill Blanks.
• Use the full range of grit sizes in sanding, do not skip stages; cross-grain marks appear easier on interlocked-grain wood than on straight-grained wood.
• Examine the board using raking light prior to making the cut so that you can identify how the ribbon pattern goes.

Interlocked Grain vs. Straight Grain vs. Figured Grain

These three terms get mixed up often, so here's how they actually compare.

What Mistakes Should You Avoid With Interlocked-Grain Wood?

Most tear-out and finishing issues can be blamed on a few simple mistakes that are easily avoidable, which should be mentioned before embarking on your first project made from Bubinga, Sapele, African Mahogany, and Padauk wood.

• Planing or routing only in one direction instead of planing in the direction the ribbon of interlocked fibers switches its direction.
• Using dull tools that instead of slicing the fibers cleanly, they tear them apart.
• Neglecting some sandpaper grits and thus leaving scratch marks across the grain that become very visible after applying the finish.
• Choosing a heavily interlocked, highly figured board for a first-ever turning or fretboard project instead of starting with milder stock.
• Forcing a cut against visible tear-out instead of stopping, reversing feed direction, or switching to a scraper.

Where to Find Interlocked-Grain Exotic Woods for Your Project

Exotic Wood Zone offers Bubinga, Sapele, African Mahogany, and Padauk in all forms of the material that are used to create items: Acoustic Guitar Set backs and sides, Bridge Blanks, Drop Tops, Fingerboards, and Headplates for guitar makers, along with Turning Blanks, Bowl Blanks, Pepper Mill Blanks, Pen Blanks, Knife Blanks, Bottle Stopper Blanks, and Hobby Woods for woodturners. In case you need to work on cutting boards or some other item in small dimensions, Thin Stock Lumber in the same interlocked grain woods provides a great possibility to have the ribbon-stripe effect without purchasing an entire board. All the pieces are shot individually so you will be able to see the level of interlocking figuring prior to purchase.

Frequently Asked Questions

1. What causes interlocked grain in wood?
   Interlocked grain occurs in wood as a result of the way that a tree's growth fibers twist and turn in opposite directions as each ring forms, eventually creating a pattern. There exist certain species that seem to be indicative of genetic predisposition for it.
   
2. Does interlocked grain make wood stronger or weaker?
   Neither does it, in other basic ways. Interlocking grain adds to resistance for splitting parallel to the length of the board because grains cross instead of lying in one direction only, but it also makes the wood more vulnerable to tear-out when it’s being cut or planed.
   
3. Which woods are known for interlocked grain?
   Bubinga and Sapele are well known exotic woods. African Mahogany is also used a lot. Padauk is another common choice. Some people also mention Sipo. And they may refer to genuine Mahogany too. These trees often have interlocked grain. You see this in many tropical and African timbers.
   
4. Is interlocked grain the same as figured grain?
   Not exactly. Interlocked grain refers specifically to fibers reversing direction in bands. Figured grain is a broader term covering curl, quilt, flame, and other patterns and it's often layered on top of an interlocked grain structure, which is why figured Sapele and figured Bubinga are especially dramatic.
   
5. Can beginners work with interlocked-grain wood?
   Of course, but using the right materials helps. For example, both African Mahogany and lightly interlocked Padauk are easier to work with compared to highly figured Bubinga. The most critical things for any artisan are sharp tools, light passes, and a complete sanding process; experience does not play any part.

Interlocked Grain, Summed Up

The wood with an interlocked grain is nothing but the wood whose fibers change their direction in repeating stripes rather than remaining in straight direction, and the interlocked grains are responsible for the ribbon-striped figure and depth in Bubinga, Sapele, African Mahogany and Padauk. Working with it is just about having a keen eye to see the direction of the ribbon stripes before cutting and using sharp tools. Whether you're gluing up a tonewood set for your next build, turning a bowl blank on the lathe, or looking for a striking exotic wood for a cutting board, Exotic Wood Zone carries these interlocked-grain hardwoods across guitar parts, turning blanks, and lumber, ready to ship. Browse the current Bubinga, Sapele, African Mahogany, and Padauk selection at Exotic Wood Zone and pick the board that matches your next project.