Using a diamond stone to remove burrs
I got these B4 Squads a little while ago and put a benchmark tune on them at work. We use a Wintersteiger belt and stone grinders and a sweet Trim Jet ceramic edger. I'll talk about machines later if people are interested. You will see the results of the ceramic edger in the photos. The tiny parallel lines at a consistent angle to the edge are from the edger. They are visible but virtually smooth. These are the same marks you'll see on new skis. The Trim Jet is the same type of machine that ski manufacturers use to prep new skis.
I took the Squads out last Monday at Keystone and inflicted a little damage. You can see that I skidded sideways over a rock (probably) and scratched the base edge and left some burrs on the side edge.
On the base edge I created 'innies': gouges in the metal that can only be completely removed by either changing the base bevel or severe grinding and re-beveling. The side edge has the remnants of the innies in the form of burrs or 'outies'. The innies aren't a big deal although they are slightly slower than a smooth edge. The outies, on the otherhand cause significant drag and are quite noticeable while skiing on firm snow. They are a hazard to your hands and clothing as well.
The first step is is work out the innies a bit. For the sake of illustration, I've used a Sharpie to mark up the edge. When you are beginning your tuning efforts, using a marker on the edges can help you see how your stone is contacting the edge.
I'm using a fairly course stone in this demonstration: a black DMT stone is what they call a 300 mesh. It will remove material quickly and makes the work go faster. On skis that really matter, you may want to use finer stones such as a red DMT. You could also start with black and redo with red. The coarser stone will leave marks of its own but as they are less deep than the innies and run in the direction of travel of the ski, the edges will be improved. Finer and finer will eventually give you a sweet, shiny polished edge.
Hold the stone so that one end is just outboard of the ski and the other end is raised in a manner that the contact of the stone is solely on the edge and mimics the base edge bevel angle. You can sight along the base edge and look for daylight (angle not matched) or no daylight (angled matched). A bright light beyond the stone can help you.
Move the stone back and forth using your inboard hand as a guide controlling the stone angle. You can go both ways because the stone is unidirectional. Move along the longitudinal axis. Your outboard hand may help the stone to track along the ski as well, but beware the outies and don't get cut. Using the marker will help you find out if you are matching the edge bevel or not. In the following photo you'll see that I used a little too more base bevel angle than the original base edge bevel (1 degree). If you have really deep innies and want them gone, this is the only way to get them out without resorting to a base grind and re-setting the base edge bevel. In this example I am slightly changing the base edge bevel. This is to favor a smooth base edge vs maintaining the base edge bevel. If these were race skis or carvers, I might leave more innie in favor or retaining the base edge bevel. As these are primarily soft snow skis, I've gone for smoother. It is also useful for you to see what happens if you don't match the base edge bevel. Most skis that are tuned by amateurs end up with an increasing base edge bevel. That is why it is recommended not to touch your base edges and leave it to a shop. With a very fine stone you can touch up your base edges as I demonstrate here without much risk of changing the bevel, but stone your base edges sparingly.
Note that the outboard part of the edge is shiny; the marker has been removed there. The next photo shows a uniform base edge polish.
Now I'll work on the side edge. Again marking the edge helps see what you are doing. Eventually you'll be able to feel and see the proper bevel angle without marking the edges.
Here is how to hold the stone on the edge.
Don't press hard, but rather let gentle pressure allow the stone to settle on the edge. Keep your thumb centered on the stone and centered over the edge. You'll note that the sidewalls were planed back (it has a greater bevel than the edge so it recedes from the edge) during the shop tune so the stone is just on the metal of the edge. My index finger is helping guide the stone.
As with the base edge bevel, move the stone forward and back along the edge. As the outies are fairly severe, the stone will drag a bit and sound rough. As you finish the stoning of the edge, the roughness will disappear along with the outies.
Before:
After:
Performing the same actions with a finer stone, then a fine gummi will smooth the edge even more. For performance carving/race skis, finish in the same fashion with a ceramic stone for the ultimate in polish. If you don't progress to finer stones, you may want to take a light pass along the base edge after doing the side edge. Every time you use an abrasive on the edge you may leave a bit of burr on the opposing side of the edge. This is known as the 'hanging burr' and is a natural result of working the metal. The finer your stones the smaller the burr. Ceramic is as fine as it gets and leaves virtually no burr.
This kind of damage can easily be addressed on the hill with a stone you carry with you. Once you are comfortable that you can match the edge bevel, just knock the outies off with a quick few passes of the stone. Focus on the side edge as that is where most outies occur.
I used still shots because the clarity is better. If a video would help you understand the motions involved, I'll set up for that.
off quickly. 
