Overview: Torn grain is one of the more difficult challenges for new and intermediate woodturners. Sometimes, even with the sharpest tools and the best techniques, it can happen while turning. Reversed grain areas, soft or punky wood next to sound wood, density differences between early and late wood, wild grain and other situations can sometimes cause grain tear out when turning. Some species are more susceptible to grain tear out than others, but there are effective ways to deal with this challenge, so your sanding will be faster and easier.
Preventing Torn Grain
Tormek T-7 10" wet grinder (left) and Baldor 8" slow speed dry grinder (above)
Frequent trips to the grinder can help to prevent torn grain
One of the best ways to prevent grain tearout is to stop and sharpen your gouge if you notice any areas that are not cutting cleanly. The edge life on your gouge is highly variable, therefore our first and best response to any cutting problem we encounter while turning, is to stop and sharpen our tools. If that does not solve the problem, then you still have lots of options available to improve the quality of your surface.
One quick and easy way to improve the cut quality in a torn grain area is to apply paste wax to the area. Simply wipe a small amount of paste wax (I use Renaissance Microcrystalline Wax) into the stubborn area and take another cut with your freshly sharpened gouge. This can be quite effective on some timbers as the wax helps to stiffen the fibers slightly, so they can cut cleanly.
Another option is to spray a bit of clear lacquer onto the area. Allow the lacquer to dry and take another cut with your gouge. This is highly effective on many timbers, so give it a try. Spray Shellac also works well, but I do not always have it on hand, so I use Lacquer most of the time. Lacquer dries very fast and really helps to stiffen the torn fibers to allow them to be cut cleanly.
Shear Scraping to Remove Torn Grain
If you do not want to apply anything to the surface, consider shear scraping the area with a freshly sharpened scraper. When we shear scrape, we hold the angle of the cutting edge at 45 degrees and lightly skim the area with the scraper. This will produce feather light shavings that look like goose down. Shear scraping is an excellent technique to deal with torn grain and offers a side benefit as well - less sanding.
Shear scraping a platter
Close-up view of the long wings used for
shear scraping on an Irish ground bowl gouge
A properly shear scraped surface can reduce your abrasive protocol up to 50%, by allowing you to start sanding as high as 320-grit. If you have my DVD video on bowl turning, there are a couple of segments on shear scraping the outside and the inside of a bowl that shows this technique clearly.
Trust me, you really want to learn how to shear scrape! I use it primarily to reduce sanding, but it works equally well to repair damaged areas.
My bowl turning video includes segments on shear scraping the interior and exterior of a bowl
Power Sanding to Remove Damage
Last but not least, you can power sand the area and remove it with abrasives. This is the least desirable option for many people, as very few wood turners like to sand! However, at times this may be your last, best option. If you have a small patch of torn grain that you want to sand, lock your lathe spindle and lightly power sand the specific area before you begin sanding the rest of the bowl.
When you have removed the damage, unlock the lathe spindle, turn on the lathe and sand as normal. The area you worked on with the lathe off will be blended into the rest of the surface and should disappear. If your damage is very deep, this option may leave a dip in the surface. There are no doubt other ways to repair surface damage, but these have been the most reliable for me over the years and I encourage you to give one or more of them a try the next time grain tearout rears its ugly head in your studio.
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.