This is what separates the men from the boys, a finished product from an unfinished product. However ,this also takes a little bit of finesse.
I have spent many years polishing stainless steel. There are several different types of finishes. The ones that I will be talking about are your number 4 finishes. Which is basically a finish that comes from the mill that has a grain to it. It is easy to duplicate if you have the right finishing tools. You can see this type of finish when go in the kitchen of a restaurant.
Lets talk about the tools that are required. One of the first things you will need is a variable speed grinder with a drum wheel or a pneumatic wheel. A die grinder with different carbide burrs. And a finger file, which is basically a miniature portable belt sander. These are the basic tools that are required to finish stainless. There are some other specialty tools that I will talk about later on.
Now lets say you just welded a stainless steel sink in a table or better yet you just welded up a corner seam on a dish pit table. I will go over both of these because your process will be slightly different. Whenever you are finishing an inside weld in a corner the first thing you have to do is to smooth it out. Restaurants don't like to see any welds because bacteria can grow in the ripples and it's easier to clean. Everything has to be smooth that will be in contact with water or food. Now the first thing that I do is I take my die grinder with a small round carbide burr on it and I lightly shape the weld. I don't spin it at the fastest rpm as this will burn up your bit. I just want to take an ever so slight amount of material out to make it smooth. Pay special attention to the edges of the weld because as you grind it you will see a line. This has to be blended in. I put minimal pressure on the bit and a low rpm. Once I have shaped it where you can't see the edges of the weld or any ripples I then switch to a cartridge roll. This is basically a roll of sandpaper that has been rolled into a cone and glued. You have to have an arbor that it will screw on to. I use a 120 grit to smooth out the roughness from the carbide burr and to blend it in. I stay in the corner. The less you stray the less you have to clean up. You just want to work on the weld and nothing else. These cartridge rolls don't last long. They are consumed at a very fast rate, especially if you are really spinning these at fast rpm's. After the cartridge rolls the weld is looking pretty good. It should be smooth without any gouges in the base metal. The next thing I do is I put on a fresh cartridge roll and then I take a fine scotchbrite hand pad and I tear off a little bit and wrap it around the cartridge roll. This is just used to blend the edges of the weld in and it puts a semi polish on it. That's it, it's that easy.
For the sink the method differs slightly. Again you just want to stay on the weld. The first thing is to take down the weld and shape it. For this I use a right angle grinder with an 80 grit sanding pad. I start in the middle of the weld and shape it. I then switch to a 120 grit pad and smooth it out, paying close attention to where the weld meets the base metal. I don't want to have to do any extra finishing so I am trying not to let the grinder slip and hit any other part of the table. Once I have gotten it smoothed out I use a flap disc with a 120 grit sand paper. A flap disc is a series of sandpaper that on an arbor that rotates in a circle. This will actually be used to put a grain in the metal. You just want to stay on the weld. After this I switch to a drum wheel that has a medium scothbrite pad. This will smooth out the roughness from the sandpaper and begin blending the weld to the rest of the metal. Then I switch to a finer pad and do the same thing. This is a process that takes time and patience on your part. Do not try to cut too many corners when doing this as it will show. Everything shows on stainless. After you do a few of these you will probably pick up a few tricks of your own. Try different things! What works for me might not work for you.
