Triangular pencils can help reduce hand fatigue if you're doing a lot of writing or drawing. However, sharpening them can be a challenge, due to their non-traditional shape. After all, most pencil sharpeners have round openings, and it's not intuitive to stick a triangular pencil into one of them. Fortunately for consumers, most pencil sharpeners will work on triangular pencils, you just have to find one that is both sharp enough to hone your pencil to a fine point and the correct diameter.
Buy a sharpener made by the pencil company. Many companies offer sharpeners in addition to their writing and drawing instruments. If your triangular pencil is of a non-standard diameter, purchase a sharpener that matches your pencil. If there isn't a matching model, contact the company for assistance.
Try standard pencil sharpeners. You can find hand and electric sharpeners with two holes, one smaller and one larger. If your triangular pencil is too large to fit into the small hole, try the larger one. Hold the pencil in the centre of the sharpening hole and twist as usual.
Use an adjustable rotary sharpener. Several pencil companies sell rotary sharpeners that will accept a wide variety of pencil sizes and shapes, including triangular. Simply insert the pencil into the sharpener and turn the crank.
Sharpen with a knife. If all else fails, you may be able to sharpen your triangular pencil with a sharp knife. Holding the pencil with the point facing away from you, slide the knife down the shaft of the pencil near the tip and shave away the excess wood until the graphite is exposed.