rocknewb101
fully equipped rock polisher
Member since October 2022
Posts: 1,368
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Post by rocknewb101 on Mar 6, 2023 9:16:30 GMT -5
Hi all - this weekend I started working with a slab of mahogany obsidian that I'd obtained from KinesavaRocks. Got all the way to 600 wheel when I started seeing scratches (ugh). Went back to the 280 electroplated, working my way to 220 smoothing, 325 smoothing back to 600 before seeing scratches again! I looked and looked in the earlier smoothing stages and just did not see any noteable scratches - did this twice - then when starting on 600 for the third time I have two long scratches on my rock that were NOT there before - almost looks like stutter scratches - is Obsidian hard to work with since it's softer? Could I have something on my disc that is causing these, and if so, what's the best way to wash the discs to get off any material that shouldn't be there. Feeling quite frustrated with cabbing right now...thanks for the help!
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Post by rockjunquie on Mar 6, 2023 9:43:00 GMT -5
Hi all - this weekend I started working with a slab of mahogany obsidian that I'd obtained from KinesavaRocks. Got all the way to 600 wheel when I started seeing scratches (ugh). Went back to the 280 electroplated, working my way to 220 smoothing, 325 smoothing back to 600 before seeing scratches again! I looked and looked in the earlier smoothing stages and just did not see any noteable scratches - did this twice - then when starting on 600 for the third time I have two long scratches on my rock that were NOT there before - almost looks like stutter scratches - is Obsidian hard to work with since it's softer? Could I have something on my disc that is causing these, and if so, what's the best way to wash the discs to get off any material that shouldn't be there. Feeling quite frustrated with cabbing right now...thanks for the help! Yes, obsidian can be hard to work. And, yes you could have contamination. I would wash my discs real well with a brush, soap and water. How do you store your disks? If that doesn't help, and it may not, try a light touch on the softer wheels. Others can chime in about working obsidian. I, too, find some frustrating. |
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Post by hummingbirdstones on Mar 6, 2023 9:43:22 GMT -5
Try scrubbing your discs under running water with a stiff scrub brush. If that doesn't work carefully use a razor blade almost parallel to your 600 lap and run it on the slowest speed with the water drip running to see if you can pull whatever errant diamond is stuck in there and wash it off the disc. If there is a diamond or two that are bigger than the rest, they will scratch soft rocks. If they are there you will hear a "ticking" noise as the razor blade goes over them Be really careful as you do this so you don't gouge your lap. Good luck!
If you don't want to use a razor blade, a piece of agate that has an edge might do the trick.
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realrockhound
Cave Dweller 
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,497
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Post by realrockhound on Mar 6, 2023 9:44:09 GMT -5
Obsidian is difficult to get a good polish. Especially on a flat lap as it holds ground off material on the plates from other rocks and leads to scrapes
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rocknewb101
fully equipped rock polisher
Member since October 2022
Posts: 1,368
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Post by rocknewb101 on Mar 6, 2023 10:12:58 GMT -5
Hi all - this weekend I started working with a slab of mahogany obsidian that I'd obtained from KinesavaRocks. Got all the way to 600 wheel when I started seeing scratches (ugh). Went back to the 280 electroplated, working my way to 220 smoothing, 325 smoothing back to 600 before seeing scratches again! I looked and looked in the earlier smoothing stages and just did not see any noteable scratches - did this twice - then when starting on 600 for the third time I have two long scratches on my rock that were NOT there before - almost looks like stutter scratches - is Obsidian hard to work with since it's softer? Could I have something on my disc that is causing these, and if so, what's the best way to wash the discs to get off any material that shouldn't be there. Feeling quite frustrated with cabbing right now...thanks for the help! Yes, obsidian can be hard to work. And, yes you could have contamination. I would wash my discs real well with a brush, soap and water. How do you store your disks? If that doesn't help, and it may not, try a light touch on the softer wheels. Others can chime in about working obsidian. I, too, find some frustrating. Thank you!! I let them dry and then put them back in their plastic sleeve. i don't think I'm being careful enough with them and that's what has happened here. I'll give them all a good scrub before trying again. Thank you!! Try scrubbing your discs under running water with a stiff scrub brush. If that doesn't work carefully use a razor blade almost parallel to your 600 lap and run it on the slowest speed with the water drip running to see if you can pull whatever errant diamond is stuck in there and wash it off the disc. If there is a diamond or two that are bigger than the rest, they will scratch soft rocks. If they are there you will hear a "ticking" noise as the razor blade goes over them Be really careful as you do this so you don't gouge your lap. Good luck! If you don't want to use a razor blade, a piece of agate that has an edge might do the trick. I have a piece of yellow cat bark that I've cut and want to polish the flat edge - I did run it over the discs yesterday, but I don't think I got up to the 600. I will give this another go, along with a good scrub of the discs and try again. Thanks for the help!! Obsidian is difficult to get a good polish. Especially on a flat lap as it holds ground off material on the plates from other rocks and leads to scrapes Yeah, that's what I think I may be dealing with here. I need to get a better system of washing them between rocks. I do a cursory wash, but it's likely not good enough - thank you!!! |
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Post by susand24224 on Mar 6, 2023 16:16:58 GMT -5
This may have been mentioned before, but I wash off my cabs-to-be between each stage, I also use a drop or so of Dawn dishwashing liquid. The cab itself could be holding something from the previous stage that contaminates the next one. Inspection is done after I wash and dry. Also, with obsidian, use a really light touch.
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khara
fully equipped rock polisher
Member since September 2022
Posts: 1,980
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Post by khara on Mar 6, 2023 17:26:53 GMT -5
You have a lot of input here but I’ll throw in one more. When I was working on the flat lap I always kept the disks stored separately in their bags like you already said. I also had a separate towel for each disk. Typically as I’m working I’ll wipe the cab on a towel to inspect it while dry. It doesn’t seem like a good idea to me to be using the same towel during all stages. I actually got super anal and bought colored towels, orange to go with the orange disk, red with red, blue blue etc. I have no idea how much this helped but at least I knew I wasn’t wiping a towel with a lot of different embedded grits onto my cab every time I dried it to look at it.
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Post by jasoninsd on Mar 6, 2023 18:14:02 GMT -5
I will add...when I was working on the flat lap, obsidian was the only material I couldn't work. I got scratches in the surface from every disk I was using. I had a thread about it...lots of advice...but danged if I could pinpoint where I was going wrong. I have an idea it was contamination...but I never could get obsidian without scratches on that dang flat lap!
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Post by hummingbirdstones on Mar 6, 2023 21:01:25 GMT -5
I will add...when I was working on the flat lap, obsidian was the only material I couldn't work. I got scratches in the surface from every disk I was using. I had a thread about it...lots of advice...but danged if I could pinpoint where I was going wrong. I have an idea it was contamination...but I never could get obsidian without scratches on that dang flat lap! I've cut velvet obsidian on a flat lap. No problem. Frankly I think the contamination thing is over rated. Yes, I put my laps when they're dry back in their bags. Sometimes that may be a week or so later. LOL! I don't wash my stones in between laps. I just wipe them off with the same towel I use until it gets too disgusting and I have to wash it. I have never gotten cross contamination on my Genie using the same water recirculating the spitters. YMMV.  I think more likely it's the shoddy quality control in China than anything anyone is doing wrong. All it takes is one or two tiny diamonds of the wrong size in the manufacturing process to completely ball up a lap. Don't get me wrong. There is such a thing as cross contamination, but when it comes to metal bonded or sintered and resin discs/wheels I believe that a diamond getting free is pretty slim. In addition, any diamond if it did get free would get washed off the discs/wheels with water and the spinning action of the same. I worry more about it when I'm using loose diamond bort or diamond paste. |
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Post by jasoninsd on Mar 6, 2023 22:41:28 GMT -5
I will add...when I was working on the flat lap, obsidian was the only material I couldn't work. I got scratches in the surface from every disk I was using. I had a thread about it...lots of advice...but danged if I could pinpoint where I was going wrong. I have an idea it was contamination...but I never could get obsidian without scratches on that dang flat lap! I've cut velvet obsidian on a flat lap. No problem. Frankly I think the contamination thing is over rated. Yes, I put my laps when they're dry back in their bags. Sometimes that may be a week or so later. LOL! I don't wash my stones in between laps. I just wipe them off with the same towel I use until it gets too disgusting and I have to wash it. I have never gotten cross contamination on my Genie using the same water recirculating the spitters. YMMV.  I think more likely it's the shoddy quality control in China than anything anyone is doing wrong. All it takes is one or two tiny diamonds of the wrong size in the manufacturing process to completely ball up a lap. Don't get me wrong. There is such a thing as cross contamination, but when it comes to metal bonded or sintered and resin discs/wheels I believe that a diamond getting free is pretty slim. In addition, any diamond if it did get free would get washed off the discs/wheels with water and the spinning action of the same. I worry more about it when I'm using loose diamond bort or diamond paste. Bragger! LOL  I'd really LOVE to think it had something to do with shoddy equipment...and not my fault in the least...so I like what you're suggesting here! LOL |
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Post by bobby1 on Mar 7, 2023 10:40:53 GMT -5
I have been working with obsidian for many years but only with 8" wheels, not flat laps. I have never had any problems with contamination. I do have scratches but it is because I have let the upper edge come in contact with the wheel. The obsidian briefly overheats and generates heat and a chip breaks loose and drags across the face of the stone and causing a scratch. If you had contamination it would cause multiple parallel scratches each time the wheel went around. They would have a fresh scratch look with sharp outer edges. I actually dry sand all of the pieces and slabs that I work on but that is a different story. Here is a slab of rainbow obsidian that is 4" across that I did recently. I grind wet but sand dry on sic 3" wide expando wheels.  |
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Post by Rockoonz on Mar 7, 2023 11:02:26 GMT -5
I agree with hummingbirdstones about chinese laps, I got a set from one of the ebay sellers years ago and there was a clump on my hard 600 that was aggravating. I believe I scraped it off with a brazil agate slab. For general lapidary purposes I never had a problem with the Ameritool discs and toppers, but I haven't bought any in a long time. The way to determine which wheel is to turn 90 degrees between laps and grind or sand till the scratches from the previous wheel are gone. If you hold your test slab in one place it will help to determine where on the disc the offending chunk is. |
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rocknewb101
fully equipped rock polisher
Member since October 2022
Posts: 1,368
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Post by rocknewb101 on Mar 7, 2023 13:43:10 GMT -5
This may have been mentioned before, but I wash off my cabs-to-be between each stage, I also use a drop or so of Dawn dishwashing liquid. The cab itself could be holding something from the previous stage that contaminates the next one. Inspection is done after I wash and dry. Also, with obsidian, use a really light touch. I wasn't doing this before with any consistency, but I'll start now - thank you for the tip! I may have been working the rock too hard - need to try again once the discs have been scrubbed  You have a lot of input here but I’ll throw in one more. When I was working on the flat lap I always kept the disks stored separately in their bags like you already said. I also had a separate towel for each disk. Typically as I’m working I’ll wipe the cab on a towel to inspect it while dry. It doesn’t seem like a good idea to me to be using the same towel during all stages. I actually got super anal and bought colored towels, orange to go with the orange disk, red with red, blue blue etc. I have no idea how much this helped but at least I knew I wasn’t wiping a towel with a lot of different embedded grits onto my cab every time I dried it to look at it. Thank you! i like the separate towel idea and didn't even consider this. I've been using the same towel over and over. I will add...when I was working on the flat lap, obsidian was the only material I couldn't work. I got scratches in the surface from every disk I was using. I had a thread about it...lots of advice...but danged if I could pinpoint where I was going wrong. I have an idea it was contamination...but I never could get obsidian without scratches on that dang flat lap! Ahhh! Would it be weird to say this actually made me feel better? I was getting so discouraged - it would look great and then presto! More scratches! I need to stop with the more difficult rocks and stick to good ole agates! Thank you! I will add...when I was working on the flat lap, obsidian was the only material I couldn't work. I got scratches in the surface from every disk I was using. I had a thread about it...lots of advice...but danged if I could pinpoint where I was going wrong. I have an idea it was contamination...but I never could get obsidian without scratches on that dang flat lap! I've cut velvet obsidian on a flat lap. No problem. Frankly I think the contamination thing is over rated. Yes, I put my laps when they're dry back in their bags. Sometimes that may be a week or so later. LOL! I don't wash my stones in between laps. I just wipe them off with the same towel I use until it gets too disgusting and I have to wash it. I have never gotten cross contamination on my Genie using the same water recirculating the spitters. YMMV. I think more likely it's the shoddy quality control in China than anything anyone is doing wrong. All it takes is one or two tiny diamonds of the wrong size in the manufacturing process to completely ball up a lap. Don't get me wrong. There is such a thing as cross contamination, but when it comes to metal bonded or sintered and resin discs/wheels I believe that a diamond getting free is pretty slim. In addition, any diamond if it did get free would get washed off the discs/wheels with water and the spinning action of the same. I worry more about it when I'm using loose diamond bort or diamond paste. Yeah, China garbage is no good for sure. This is the Hi-tech Diamond company - they SAY they are made in the USA, but maybe parts are coming in from China...I'm not sure. Thanks for the insight! I'll keep on keepin on... I have been working with obsidian for many years but only with 8" wheels, not flat laps. I have never had any problems with contamination. I do have scratches but it is because I have let the upper edge come in contact with the wheel. The obsidian briefly overheats and generates heat and a chip breaks loose and drags across the face of the stone and causing a scratch. If you had contamination it would cause multiple parallel scratches each time the wheel went around. They would have a fresh scratch look with sharp outer edges. I actually dry sand all of the pieces and slabs that I work on but that is a different story. Here is a slab of rainbow obsidian that is 4" across that I did recently. I grind wet but sand dry on sic 3" wide expando wheels. I wish I took a pic of it - at first I thought it was a crack, but looking closer you can see almost stutter marks, if that makes sense. it's such a fine line between too much pressure and not enough...That rainbow obsidian is beautiful. I agree with hummingbirdstones about chinese laps, I got a set from one of the ebay sellers years ago and there was a clump on my hard 600 that was aggravating. I believe I scraped it off with a brazil agate slab. For general lapidary purposes I never had a problem with the Ameritool discs and toppers, but I haven't bought any in a long time. The way to determine which wheel is to turn 90 degrees between laps and grind or sand till the scratches from the previous wheel are gone. If you hold your test slab in one place it will help to determine where on the disc the offending chunk is. I think it's the 600 that is causing me issues - was fine until I started working with that disc. I'll take my pet wood and try to wear down just in case there's an errant diamond somewhere. Thank you!!! |
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realrockhound
Cave Dweller
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,497
Member is Online
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Post by realrockhound on Mar 7, 2023 14:18:28 GMT -5
Two pairs of optivisors minimum. You want to be able to see into the atoms that make up the material. That way, you’ll be sure to get zero scratches.
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Post by jasoninsd on Mar 7, 2023 15:14:57 GMT -5
khara - I figured you'd want to hear that someone else had A LOT of difficulty working obsidian on a flat lap. I totally get all the advice everyone had given me...and all the advice they're giving you...and that people DO have success with it...but no matter what I tried, I just couldn't get the dang scratches to stop! I really do hope you're able to figure it out...it would be a serious "win" if you do!!
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Post by Lazy Perfectionist on Apr 11, 2023 14:44:34 GMT -5
I will add...when I was working on the flat lap, obsidian was the only material I couldn't work. I got scratches in the surface from every disk I was using. I had a thread about it...lots of advice...but danged if I could pinpoint where I was going wrong. I have an idea it was contamination...but I never could get obsidian without scratches on that dang flat lap! I had exactly the same experience - over and over, with all disks >600 (except for my treasured 800 which seems impervious). Since I will suddenly get a deep scratch in the midst of polishing nicely, I've concluded that it isn't contamination. I think it is due to a tiny chip coming off the obsidian piece and embedding into the disk. I haven't found a solution yet, but I am trying to ensure there are NO signs of chipping, pits or ash pockets before I go to the higher grits. I have a long list of different disks I've tried, but none have really been successful. Sigh. |
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