Obsidian - I Really Don't Get It...And Feeling Frustrated

The fact that the scratches on the last photo are all going in two directions may suggest that you are not altering the angle at which the stone contacts the wheel enough. It can not remove scratches that are parallel to the rotation of the wheel. If you are not pushing, maybe you should. Letting the stone kiss the wheel without force can let it hop around and miss areas. The reason why soft wheels are soft is so you can push against them and get to a larger area (often necessary to get central scratches and flat spots) although that does not seem to be your problem. In my shop 3000 is not for anything with visible scratches. Those have to be removed down at 600 and then using higher grits to change a satin surface into a mirrored one. I hope that makes sense. You know what you are doing you just are stubbing your toe on this one.

That sucks!

I get it that if I miss scratches, that I have to go back and get them out...but I just don't understand how I keep "gouging" practically everything with these 8000 and 14,000 disks.

If it's a harder material, they create scratches... but the softer material just creates gouges...


I know it's got to be something I'm doing wrong and I can't seem to figure it out or fix it...

Thank you for letting me know this.

I'll give that a try.

I figure for as much money as I put into those two disks they should be polishing anything and everything...and washing the dishes! LOL

See, it's the universe telling you to order that cabbing machine

After finishing a few hundred fire obsidian cabs, I'll share what I think I know LOL - hopefully some of it will help.  I've done all the swearing, pulled out hair, spent money unnecessarily, etc., so I know your pain.  The way I work obsidian now, if scratches exist on my finished obsidian cabs, you can't see them with 3x readers behind a 2.5x opti-visor.

I use soft wheels, but if your not trying to jam the cab into the disc I feel like the grit should dictate what happens to the surface of the cab, soft wheel or hard disc.  The biggest thing that stood out for me in your description was "I went back to the 1200 until they seemed shallow enough to go back to the 3000".  I'm assuming you're drying the stone off and checking it before moving up in grit?  If you can see the scratches at all on your current grit then you're either not done at that current grit, or you really need to step down a grit or two.  If none of these have been to a polish stage yet, then I think most likely you just moved up a grit too early somewhere in the process.  Not trying to discount Peruano, but I've had those scratches from multiple directions just like that using soft wheels on a CabKing.  I'm 99.9% sure it was just from working the stone normally at the lower grit and I just didn't get them knocked out properly before moving up, somewhere in the line. As I mentioned already, if you can still see scratches (even shallow), then you're either not done at the current grit or you really need to step down because you moved on too early.  Not to say you couldn't eventually get them out, but at 1200 or higher you're going to be there for days trying.  I dry and inspect the stone with the glasses and optivisor between each stage, but I still get bit by impatience at times and feel sure I got all the scratches and skip the dry/inspect, and that always makes me walk it back down a grit or two.  I guarantee you don't need to go beyond the 3000.  In fact, for a while I finished a bunch of them on 1200 (before polish) because I thought my 3000 wheel was contaminated.  Are you running a lot of water over the discs?  Any chance you have some contamination?  The obsidian is not very forgiving if you have a little contamination from harder material, like the agates you've been working.  Assuming there is no contamination, my process is the following:

1. Rough form the cab with a 220 hard wheel.  For the fire obsidian that means taking the face down to where there's about 3-4mm of glass on top of the magnetite layer

2. Next is the 280 soft wheel.  I spend quite a bit of time on this one generally, then I dry and inspect.  If I can't pick up any scratches or grooves, then I move on to...

3. 600 soft wheel.  Same story, spend as much time here as I need to until I can't catch anything when the stone is dry

4. 1200 wheel....same as above

5. 3000 wheel...same as above

6. Cerium Oxide or Super Cerium Oxide on felt

If you haven't hit the last stage yet, that's a whole other ballgame I'm afraid.  No real tricks to share, in my opinion success on the polish stage relies quite a bit on hands on experience.  You have to balance between it being too wet, or not wet enough...and also having enough CO, or too much.  I have the best result when it has the consistency of creamy peanut butter, maybe just a hint more wet than that, but really close.  If you have too much, and/or it gets too dry then the CO can bunch up in little balls/chunks and cut finally polished grooves in the glass - they look like scratches but without the white coloring a scratch has.  If that happens, then you're back to 1200, or probably a short run on the 600 and then regular times on the 1200 and 3000 again.  This issue was the most frustrating thing for me when learning how to work with the material because for what seemed like forever, I was blaming the wheels.  This was the biggest "Aha!" moment for me, so if I can help you avoid it, I will.  Vince brought it up recently-ish in another thread, and I can't tell you how important this piece is, it was not fun learning the hard way LOL.

Last thing I can share is if you work an obsidian cab or specimen that has an uneven surface, like maybe you want to keep natural contours for some reason, the concave areas won't get any love from the felt disc.  In those cases, I've hand polished those spots using a clean leather chamois from the automotive section of the hardware store.  Just get it damp, give it a little charge of cerium oxide and then some good old elbow grease   I've been doing some obsidian sculptures recently and use that same method for the hard to reach places where a felt Dremel tip is too risky.  It's not as bad as it might sound, and it's oddly satisfying to see what you did by hand.

Hope something in here helps!

rockjunquie - Tela, I did search through tntmom's threads, and saw her tutorial on tumbling, but didn't find anything with regards to her method on cabbing...unless I missed it.

jasperfanatic - That was a very time-consuming post...and I am VERY appreciative of you posting all of that. In response:

- I believe in listening to the universe...and I'm pretty sure you're not wrong with regards to the cabbing machine!

- I'm looking for scratches through reading glasses, through 3.5x opti-visor, then through a 3x magnifying lamp...basically as good as a loupe. This combination really zooms in for me...

- I am drying the stone off when looking for scratches. I was chasing my tail when I was first starting cabbing because I was seeing "scratches"...but what I was told at that time was because of the amount of magnification I was using, I was going to see scratches...but they'd decrease as I progressed through the grits. I thought I had it down pretty good...but maybe I don't.

- I'm 100% certain those "scratches" in the 3rd and 4th picture are not from "missing" them in the earlier stages...the ones in the second picture are. The scratches in the last two pics are high or clumped diamonds on that dang 8000 disk that gouged the surface. They weren't there when I started the 8000 stage...I know that for certain.

- Maybe all my dang disks are contaminated. When I take these back to the 500 stage, I can see scratches being created...albeit very shallow ones...no matter what direction I go with the cab. I can only see them through my triple magnification. The 500 takes out the scratches from the earlier stages, but leaves it's own "shallow" scratches...not gouges like the 8000. When I go to the 1200, it takes out the scratches from the 500, but leaves it's own shallower scratches of it's own. And then the same thing with the 3000 (which is a BRAND new disk that I put on this morning because I believe the old one WAS contaminated and no matter what I did to try and get it out, I couldn't - so I replaced it because it was gouging everything like the 8000). I am running a lot of water as I go...but maybe not enough...

- I'm definitely not trying to blame the 8000 disk. I'm certain it's something I'm messing up...but I can't seem to figure out what it is. I know the 8000 is gouging the surface...and not "exposing" the scratches that haven't been removed. I don't know how I'm cross-contaminating if that's the case. I keep the 8000 and 14,000 disks clear across the room totally away from the cabber so I wouldn't cross-contamite.

- It seems I have two separate problems I'm encountering. I'm apparently not getting the scratches out like I'm supposed to be - which I thought I was. And then secondly, the 8000 and 14,000 disks ARE creating gouges (as in high or clumped diamonds) - and I can't figure out why they'd be doing that either. Again, I'm 100% certain these aren't "exposed" scratches...they're newly created gouges.

I have done Obsidian on that same machine with the disks that come with it and have done a darn good job. That said, I've also had to go back and start at the beginning multiple times.

Keeping those finer grits separate are necessary. I've also learned to wrap them, and not stack them on each other. Otherwise, any little contamination will show up
Also keep your polishing pads separate and wrapped.

Also feel your pads, you may have created a "gouge" with something and not know it

My suggestion keep separate disks for obsidian, slag, Goldstone etc.

Hope that is some help

Just an observation from long ago. I haven't cut much obsidian in recent years but I recall from the "olden days" before the diamond "revolution," I didn't have problems when I used silicon carbide sandpaper dry. Yes, I know...but I'm still kicking.

As I recall the trick was allowing the paper to "load" with sanded material thus slowly reducing its cutting ability resulting in a finer and finer surface without scratches. I don't recommend dry sanding on a regular basis without masks and careful ventilation, but now and then it might be justified to solve problems like yours. If you do it touch the stone to your cheek often to check for overheating. Too much heat will break the stone - very dangerous with volcanic glass.