Alan Turner and Mario Rodriguez*, two well-known and talented woodworkers, were the guest speakers at our most recent woodworking club meeting, a combined meeting with another club. Alan started his own woodworking school several years ago, The Philadelphia Furniture Workshop, where both he and Mario are instructors.
Mario demonstrated mitered through-dovetails and Alan demonstrated how to sharpen
a scraper. Alan sharpens them a little differently than I do, so I decided to have a showdown between his technique and mine. I used the same scraper, a Sandvik, and sharpened one edge with my technique and the other edge with Alan's.
Here’s my process:
Chuck the scraper in a vise, and using a
smooth 
file, square each edge 90º to the sides. Switching to an 8,000 grit waterstone, hone the edge. Skew the scraper as you hone, so you don't plow a groove in the waterstone. Next, hone 1/2" of the face of both flat sides. Put some oil on a burnisher (some people use the handle of
a screwdriver, but I have better luck with a burnisher), hold the scraper in your hand** and, using a fair amount of downward pressure, slide the burnisher 3-5º along both sides of 
each long edge, 5 or 6 times. The idea is to create a hook on both sides of the ed
ge so you can use both sides to scrape.Here’s Alan’s process:
First, he oiled the scraper and the burnisher. Then he laid the scraper flat on the workbench near the edge and used the burnisher to draw the metal out along each long edge on both sides of the scraper, creating a “U” shape of metal along each edge. Then he chucked the scraper in a vise and filed the edges to 90º. He added more oil to the scraper and burnisher, then he drew the metal out once more on the workbench. Back to the vise, he burnished each side of each long edge 2-5º.
To use the scraper, flex the blade between your thumbs
and hold the scraper at 45º to th
e work surface. The moment of truth....They looked the same to me. I was surprised because I thought Alan's would work much better. I still think his is a better sharpening technique that will produce more consistent results. But, take your pick!
*Photos of Alan and Mario courtesy of Robert Aspey.
**It's possible to cut yourself by holding the scraper in your hand while using the burnisher, so to be totally safe, you can secure it in a vise instead.