SIC powder.

[Legion]

Lately I've been reading up on Arkansas stones, and I think it is just a matter of time before I find one that I need to flatten, and I don't want to kill my Atoma.

Looking for hints, tips and recommendations for using SIC powder.

Grit? Surface materials? How much?

How do you guys do it?

 

[LJS]

I use a progression of grits and I think others do too. Mine are something like 80, 120, 240, 360 etc. I have some finer too but normally this is enough.

I use a much larger ceramic tile that is something like 1’ x 2’ for the grinding surface. I have several I bought cheap one time and they wear out after some use.

Trial and error will tell you how much and what to do but start with maybe a teaspoon of SIC, get it wet but don’t wash away, and see what you think doing swirling motion or back and forth. Needs to remain wet or at least for me. Actually I let water run the whole time lightly as it helps flush the stone-swarf out of the SIC powder which clogs its cutting power.

Few things to make note of:
#1 and pretty important I think - SIC, especially coarse grit, can eat out poc marks in the Arkansas stones if not careful. I think putting too much pressure and not enough water/lubricant leads to this. If it happens, only one way to fix and that is to grind out with more work (and less pressure)
#2 it breaks down like sandpaper and you will notice. Early work grinding you may need to add more. Finer stuff it works out and just gets finer
#3 SIC will actually convex your stone slightly. I still finish up last lapping and final surface finish using W/D or diamond plate

Good luck!

 

[kcb5150]

Get a couple of sample granite tiles from a hardware store. Use the sic directly on one for the heavy lifting removal. I find this goes along quicker when things aren't overly wet. Once you kill a dish on a tile this way you usually have a hump and 4 lowish corners so I take another tile, put something lkke 120 grit wet dry on it, sprinkle some sic on that and reel it back till it is close. Then I start with just wet dry to zero it. If you are on septic do it outdoors

 

[kcb5150]

That shot peen effect comes out anyway once you move to fixed grit.

 

[Tomo]

Compared to diamond plates and sandpaper, loose SIC is cheap. I use it to stretch the life of my early work sandpaper. Once the 240 grit paper looses its bite, I sprinkle on a little 180 grit SIC on it and I’m back in action.

The SIC is hard and brittle. It breaks down into a finer and finer powder with use. I will do a couple of SIC applications and then change the paper. You can remove water and swarf from the surface with paper towel and add more.

Once I get there with the SIC powder I complete the progression with just WD paper on a granite surface plate.

Pro tip. Don’t rinse the SIC slurry down the drain. Like sand it will eventually block the u bend in the drain. Better to put it in the bin. It’s not great for you to breath the powder. Keep it wet and dispose of it properly. Someone had an idea to work the SIC in a cheap baking tray to contain the mess. Seems like a good idea too.

 

[Legion]

So I have a pretty thick piece of glass I use for putting wet dry paper on. If I was to choose one grit to use for flattening (and then finish on finer paper?) what grit should I buy? 120- 180?

 

[Wid]

Most time I start out with 240 and end with 600 and then 1K wet/dry paper. I've only had to use 80 grit once.

If using one to get it flat I'd go with the 240 grit.

 

[buca3152]

60 grit for the heavy lifting. And then I typically use an atoma 400 to finish it off.

 

[LJS]

So I have a pretty thick piece of glass I use for putting wet dry paper on.

If you value that glass then get something different for the SIC. It will eat it up faster than you might expect. I use tiles because they are disposable.

 

[Legion]

If you value that glass then get something different for the SIC. It will eat it up faster than you might expect. I use tiles because they are disposable.

I got it for free, so I guess it is not something that I value too much. I reckon my chances of finding free glass is better than tiles.

I can get thinner glass for near free all day, by buying old picture frames from the thrift store, $2 a pop, and I can discard the glass when it wears. I don’t have anywhere local to get perfectly flat tiles.

 

[camoloc]

I used 120 and 220 SIC powders on a marble tile I bought from a local store.

between the surgical Ark and the jasper I worked on.........the marble had a spot in the center from the work.

guess over time I could tile a small room in my house with marble..........that has strange spots in the middle of the 12 x 12 !

camo

 

[buca3152]

I used a lapping plate that I bought from woodcraft. I also have used glass and granite tile. Unless your flattening stones all day I don't think you will have to buy another one..and besides that the sic I wouldn't recommend for finish lapping. As you may get some grit in the stone. Which is no bueno.

 

[H Brad Boonshaft]

I buy Silicone Carbide grit from GotGrit.com. $15 will buy you a progression from 60 to 500 grit. 60 is what will get you flat and lap several stones.

Buy a Steel cookie sheet, (Glass, Marble& Granite will dish in a few laps) from the Dollar store sprinkle a tablespoon on a wet sheet to make a paste. Put the sheet on flat cement floor, use your body weight and lap it with pressure, you will see the wear on the stone or can grid mark with a colored sharpie, (pencil will wash off with slurry, so will sharpie, so grid often and do a final grit and lap test). Add water and 60 grit as needed, you can feel when it stops cutting. Rinse the slurry on to your lawn, not down the sink.

Stay on 60 grit until flat, then you can proceed up the grits quickly once flat. From 500 I go to Wet and Dry; it sticks to a clean wet cookie sheet.

The trick is getting flat, unless your stone is deeply dished 20-30 minutes on 60 grit will get you flat.

Don’t waste a diamond plate, arks will eat a diamond plat quickly. India and Carborundum stones are great for re surfacing Arks, then take them to finish with Wet and Dry. I do one side to 600 and 1k the other and burnish the 1k with a carbon steel cleaver that I can lean into on the floor.

If you need to surface a deeply dished stone, us an old metal file to hog off material, then grind flat with 60 grit. You will trash the file.

Glass and stone go out of flat quickly, ask the guys that calibrate granite surface plates and that is just from the dust and grit that gets under the Wet & Dry, so imagine what happens with 60 loose grit.

Glass is not flat but can easily be flattened with 220 Wet &Dry, it is actually pretty soft.

 

[Toro Blanco]

+1 on the steel cookie sheet. Especially for the beginning grunt work!

I go 80,120,220 on the cookie sheet then switch to 400,600,1000 WD on flattened marble tile checked by a straight edge. Not all tile is dead flat.

Depenfing on the stone I might use a well used Atoma to finish off.

 

[global_dev]

I use it to stretch the life of my early work sandpaper. Once the 240 grit paper looses its bite, I sprinkle on a little 180 grit SIC on it and I’m back in action.

The SIC is hard and brittle. It breaks down into a finer and finer powder with use. I will do a couple of SIC applications and then change the paper. You can remove water and swarf from the surface with paper towel and add more.

Once I get there with the SIC powder I complete the progression with just WD paper on a granite surface plate.

Pro tip. Don’t rinse the SIC slurry down the drain.

I kind of do the same. I am suprised by how quickly the sic seems to loose effectiveness. And its noisy.

I never tried the paper towel process to remove the swarf.

 

[Tomo]

I kind of do the same. I am suprised by how quickly the sic seems to loose effectiveness. And its noisy.

I never tried the paper towel process to remove the swarf.

Yeah you can really hear it grinding. It sounds super aggressive to start.

I use the paper towel to make sure that there isn’t too much SIC water on the sandpaper. I don’t want to get the slurry going off of the edge of the sandpaper on onto the surface plate. Using the sandpaper dry on the plate makes it pretty easy to tell if something has gotten underneath.

 

[Gamma]

SIC will eat most surfaces used for lapping. I have killed one side of a dead 10x4 DMT lapping with the stuff. If I use sacrificial layers of sandpaper of equal or finer grit the lapping surface lasts longer.
Lapping directly on granite or marble with 60-200x SIC usually knocks the surface out of flat pretty quick.
For most Arks I start on 60x then 80x, 120, 220, 320, 400, 600. Finish lap on 600x WD.
4-5 sessions on 60x usually brings an Ark into submission. Flatness needs to be established here, making it up later is difficult.
While working, If the lapping slurry builds up in one place under the stone, and not so much in another place, achieving flatness becomes elusive. The density of the SIC/Water paste should be consistent in density and thickness.
4 oz of 60x will get me through a bunch of 8x2" stones - 4 oz of 600x will last me almost forever.