Sandpaper grit for stainless?

[stealth71]

I just began polishing and I have some pitts and scratches I can't get out w/ the black compound. I think I need to sand it first. I tried searching, but didn't find an answer.

What grit should I start with and move to until the black compound?

This is a 4" tube.

Here is a pic:


Thanks

[alabama_lowlife]

see how well 400 or 600 does it. if the pits are too much to get with that, then work back to 320 or 220 if you have to, then go back up to 600.

[stealth71]

I tried 600 dry by hand and it barely did anything. I guess I need to try a little coarser. Wet or Dry? By hand or power?

[pickleboy]

Originally Posted by stealth71

I tried 600 dry by hand and it barely did anything. I guess I need to try a little coarser. Wet or Dry? By hand or power?

one way to start is having lots of grits on hand and compare the paper to the scratch/ pit. the paper that is the closest to the scratch is most likely the depth of the scratch. move up one grit and start there. as for hand or power that is your choice. just keep in mind that the areas that have little to no scratching you should try to stay off of. as you sand you will put scratches on that will have to be taken off with the next higher grit. i would work up to 400 dry then redo with 400 wet and progress through 600 wet. this is about where sisal and emory start out. from there move to spiral and emory, then on to spiral and green. finish off with spiral and white. if this still is not the shine you want try some red on spiral or loose. hope this helps bro.

[Rasper]

Sanding stainless by hand is a losing game. It's just too hard. You have to use a machine, unless you have a long, long time and a lot more energy than I have. I polish a lot of stainless, and I use a 3000 rpm machine with a soft pad. I usually start with 150, unless the metal is scratched badly, in which case I use 80 first. I go 150, 240 and 400. I use worn out 400 as a finish sanding, then go to emery on a stiff buff. I don't find it necessary to go higher than 400. Using the worn out 400 is enough.
Another thing. Stainless loves sandpaper; it eats it up. You might as well buy a lot of it. I have a little 3 inch air machine by Chicago Pneumatic and use 3M hook-it discs at 50 cents apiece. I can easily use up 50 dollars worth of discs in a day. Stainless is hard. It is hard to cut; it is hard to shape; it is hard to planish; and it is even harder to sand. The funny thing is: once I get it to the emery buff it polishes up fast. You need to bear down on it some, but it comes right up. Then I use green polish and then chrome rouge.
The important thing is, (and no one wants to hear this), you absolutely have to sand out all (and I mean ALL) of the scratches left by the previous grit sandpaper before you move on to the next. This takes a lot longer than you think, especially with stainless, a lot longer. But if you don't get them out, you will have to start all over again.
Get yourself a machine and a soft pad, if you have to rent it, borrow it, or sell your great mother's jewelry for it. You will save yourself a lot of grief.

Richard

[Rasper]

Ever since I wrote the previous post I've been thinking about how to wet sand stainless using that little Chicago Pneumatics polisher. My current project is made from 22 ga. sheet metal, and the heat from the dry sanding does funny things to it. I have to keep planishing it out. So I tried something today. I use a 3M hook-it soft pad. I took a piece of cloth backed sandpaper and soaked it in warm water for a while to get the glue and the sanding grit off, and then dried it in the sun. I glued it to the soft pad with weatherstrip adhesive, which gave me a surface to glue wet-or-dry sandpaper to, using feathering disk adhesive. The initial test seems to indicate total success. The sheet metal stays cool; wet sanding cuts better than dry; and it's a whole lot cheaper than 50 cents a disc; I can cut maybe 12 three inch discs out of a 50 cent sheet of sandpaper. One downside though: I got soaked; it throws water everywhere.