Options for Inlay Materials

Turquoise inlaid Olivewood hollow form

Overview: There are many different inlay materials that make good fill for voids on your projects. While you may opt to leave some of these voids unfilled on certain projects, at other times you choose to fill these voids to accent your turning. This is one of those areas in woodturning where most folks either like the look of filled voids, or they dislike them.

It was not all that long ago that I preferred the look of open voids, but I've since changed my mind, at least on some projects. Depending on the style of the project and the timber, a nicely filled void can be a very provocative addition to the turning, enhancing the overall visual impact of the piece. Here are a few tips to get you started with filling voids and channels in your work.

Pre-Sealer First: When you're ready to fill a void, crack, hole, or channel in your project, you need to consider pre-sealing the area to prevent the inlay binder from wicking into adjacent timber cells. Spray Shellac and Lacquer work well for this task and are usually on hand in most woodturner's studios. Remove any dirt, or debris from the area with compressed air prior to sealing. Larger bits of loose bark and frass can be easily removed with old dental picks (you can get these for free from most dentists).

Once the area has been cleaned of any loose bark, dirt, sawdust, or uninvited guests, spray the sides, bottom and the adjacent area around the fill area with spray Shellac, or Lacquer. When the spray finish has dried, you can install the inlay material. If you choose not to pre-seal your fill areas, thin binders like cyanoacrylates (Super Glue, or CA) and thin epoxy can wick into adjacent timber cells and darken the wood. These areas will become very visible when you apply your final finish. To prevent this problem, always pre-seal.

Spray lacquer can be used to pre-seal the inlay area to prevent discoloration

Binders: Most inlay materials are set using various viscosities of cyanoacrylates (CA's) or thin binary epoxies. You can also use other materials like Polyester resins as binders, but they are harder to work with if you're not experienced with these types of resins. I use both CA and thin binary epoxies for most of my inlay binders however, I'm starting to use polyester resins more and more for some projects where the unique properties of these resins can be advantageous.

Polyester resin is an excellent binder for many inlay materials

CA's are popular binders for
many inlay materials

Fill Materials: Almost anything can be used as fill material. Among the more common materials used by woodturners are crushed stone, sawdust, metal dust, metal shavings, coloured resins, coffee grounds, stone nuggets and plastic pellets to name a few.

I've seen hundreds of different items used as fillers on woodturnings. Some worked well and accented the project, while others looked really bad and degraded the overall look of the piece. The lesson learned here is to always practice on a scrap piece of wood before you risk using a new fill material on your expensive bowl, hollow form or pen blank. Don't ask me how I know this…

Brass shavings are an inexpensive and
popular inlay with many woodturners

If you use a lot of crushed stone, making a stone crusher can save you a lot of money

Tools to Make Your Own Crushed Stone: If you like the look of crushed stone in your work, but cringe at the thought of paying $10.00 USD for a small one-ounce bag, fear not. You can easily crush your own stones for a fraction of what you have to pay for crushed stones at most woodturning stores. I use a lot of crushed stone in my studio, so I had a friend of mine make me a stone crusher. This allows me to purchase rough stones, scraps and off-cuts from jewelers and crush them myself as needed.

Rough stones are loaded into the metal tube and the ram is replaced and struck with a hand held sledgehammer until the stone is broken. Sifting screens are then used to grade the crushed stone into three different sizes. Another advantage of crushing your own stone is that you can use a much larger variety of stones in your work than what is commonly stocked at woodturning stores.

You can save a significant amount of money by crushing your own stone, but only if you use a lot of stone. If you will only use a small amount of crushed stone now and then, it's cheaper to buy the pre-crushed stone. It's ready to go right out of the bag and it's easy to use, but it's none too cheap in large quantities.

Scrap stone chips can be purchased inexpensively from most jewelers or rock shops

Wood shavings are an easy-to-use and
inexpensive inlay material for woodturnings

Inexpensive coffee grinders can be used to produce finely grated sawdust for inlay material

Abrasive Considerations: One key point to remember with fill materials is that the area will have to be sanded (in most, but not all cases) with abrasives, so make sure whatever material you choose, that it can be sanded with the abrasives you use in your studio.

When working with crushed stones, observe the Mohs hardness scale to insure your fill stones can be sanded with your abrasives. If you purchase your stones from woodturning supply stores, you don't have to worry as all of the crushed stones sold can be easily sanded with standard abrasives. However, if you get into crushing your own stones, check the Mohs scale before purchasing any new stones.

Safety Note: Always follow all manufacturers safety instructions before working with your lathe, or any of the tools or products you may use. If you are unsure about any operation, obtain competent professional instruction before proceeding. Use and wear all necessary safety devices during turning and observe safe woodturning practices to prevent accident or injury.

Steven D. Russell is a professional studio woodturner, teacher and writer. He has written numerous articles for international woodturning magazines, which have been published in more than 78 countries around the world. Steve has demonstrated in numerous cities across the United States. His studio, Eurowood Werks, specializes in bowls, platters and hollow forms with unique visual and tactile treatments.

Steve is also the current and founding President of the Lone Star Woodturners Association, Inc., an AAW member chapter. The LSWA is a 501(c)3 non-profit educational organization dedicated to teaching and demonstrating the art and craft of woodturning.

Steve is also a featured writer for the Guild of Master Craftsman's "Woodturning" magazine, published in London England. Woodturning magazine is the world's leading magazine for woodturners. Look for his articles covering technical topics, or project based articles in an upcoming issue.