Working with Exotic Woods
Here in North America we have access to some of the world’s nicest furniture making woods. That said, I always find myself being drawn to some of the more exotic woods from around the globe. Timber like rosewoods, wenge, or ebony always interest me when it comes to small objects or accents to things that I build. As beautiful as they are, some of them definitely require extra thought and care while using them.
Some exotics can cause allergic reactions. Not that domestics woods are safe for all to use, there are just more examples of exotics causing problems. Exotic woods are also typically harder and require a different approach when it comes to tools and surface preparation. There are also considerations to be made when gluing exotic woods. Let’s take a look at some of the practises I use when working with this beautiful stuff.
As beautiful as these timbers can be, they can sometimes cause health issues. They are like a milkshake - how can something so tasty cause an ice cream headache? Many woods, including domestics, can cause a range of allergic reactions that you should be aware of. They can range from a simple skin rash or watering eyes, to something more severe like vomiting. Some woods are also classified as sensitizers, meaning that the reaction you get will get worse with every subsequent exposure.
When I was a student at Rosewood Studio I had a severe reaction to makore. This species of wood is associated with the following symptoms: irritation, nausea, headache, giddiness, and nervous system/blood effects. Needless to say, I don’t work with makore any longer. The Wood Database has a great chart that lists some of the worlds most common woods that can cause health issues. This doesn’t mean that you will have the reactions listed. It’s simply something to consider when you are deciding on a new wood to work with. It goes without saying that you should always be reducing the chance of inhaling wood dust through effective dust collection systems and/or wearing a mask. Wood dust is a known carcinogen, so please take appropriate measures.
When working with any of the tropical hardwoods like rosewoods, it’s best to take more care when gluing them up. Tropicals are typically extremely dense and oily which can cause issues if you use water-based adhesives like PVAs. The oil resists water-based glues and can cause a joint failure. It’s important to note that the resistance to PVA doesn’t always happen, but it is something to consider. I prefer to not take chances with this, and thankfully there are a few simply techniques that can make adhering these woods a bit more effective.
The first thing I like to do is scuff up the surface with some 150-grit sandpaper. Tropical hardwoods are incredibly dense. Combine that with the oiliness and the glue will not be able to penetrate the surface. Sanding helps, but don’t over do it because you can end up taking the glue surface out of flat, causing even more problems.
The next thing I do is remove some of the surface oil with a rag and solvent. There isn’t a hard and fast rule as to what solvents will do the trick. Depending on the species, oil content, and density, I will experiment a bit to figure out which solvent to use. Some of the most common solvents that seem to work are: mineral spirits, lacquer thinner, denatured alcohol, and acetone.
Speaking of glue, there are some considerations here as well. I avoid using PVA glues of all types simply because the risk of failure is too high for me. Instead, I prefer to use an epoxy resin as my adhesive of choice for these exotics. A thin layer is all you need and I have found good results with EcoPoxy brand epoxy. I personally like this brand because epoxies tend to give me a headache when working with them, but the EcoPoxy doesn’t. No need for headaches.
It’s pretty safe to assume that you can all but put away your hand planes when working with many exotics. That certainly doesn’t mean that I don’t try though. In my experience, you need to use high cutting angles to get them to tame these hard woods. I usually try 60° or higher which means either using a wooden plane with a high angle blade bed or a bevel-up plane with at least a 50° blade bed. This high angle will result in a Type 2 chip that fractures the shaving early and often making it more difficult for the wood to tear out.
It’s also important to ensure that the plane you are using has a tight mouth opening. The tighter the mouth, the more support you will get directly in front of the blade, which will in turn reduce the chance of tear out. With blade angle and mouth opening covered, it’s time to move onto maintaining the blade’s sharpness. This is perhaps the most important factor when using a plane to work with exotic woods (or any woods) Blade sharpness is one of the most important factors to a plane’s performance. Many exotics have a blunting effect on tools because of mineral deposits or silica in the wood. This means you will be doing a lot of sharpening, not only to your planes, but any other tools you use.
I find scrapers to be the most useful tools to use on exotic woods. Scrapers all but remove the chance of tear out and leave a beautiful, lustrous surface on the wood. Card scrapers do a fine job but keep in mind that they don’t have a sole. This lack of sole can lead to uneven surfaces, especially if you are working in a small area that may have tear out. The #80-style cabinet scraper is my tool of choice if I’m going to scrape a surface. They are fairly easy to set up and have enough sole to prevent taking surfaces out of flat. You can also use a scraping plane, but these tools are notoriously tricky to set up and can cause more headaches than dealing with the wood itself.
The final option is always sanding, but it’s important to work with a sander that has great dust collection like the Festool sanders and dust collection systems. As I personally found out, even just a small amount of airborne makore dust was enough to induce coughing, watering eyes and a runny nose. Please don’t take any chances with your health. We have to stay healthy if we want to keep woodworking!
Using exotic woods is a great way to spice up your woodworking colour palette as they can add interesting grain, textures, and figure to your work. They require a bit of extra care and consideration, but they are worth the effort in my opinion. The best way to get familiar with these woods and their qualities is to simply try them out. In order to understand, you must do.