January 24 Through February 4—TUCSON, ARIZONA: Annual show
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 Post subject: Information Requested Concerning Jet
PostPosted: Sat Aug 26, 2017 10:14 am 
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Decided to repost this to the beginners forum. Hope this will be satisfactory? If I am out of protocol you can just tell me where to go.

Obtained a chunk of jet (Russian origin) looks promising. The Seller purchased this at the Tuscon Show for resale but is not familiar with the lapidary procedures. Would like to know if I could get some help from the forum concerning Jet? Such as, what the best lubricant to use when slabbing. Mineral oil, water, soluble oil, etc. What procedure you use to bring this material up to polish. Any and ALL suggestions or information would very much be appreciated. Thank you very much for taking the time to assist this senior citizen with this matter. Ivan USAF 62-66


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 Post subject: Re: Information Requested Concerning Jet
PostPosted: Sun Aug 27, 2017 1:10 am 
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I have a small specimen of jet given to me by Conny Forsberg FGA, a Forum member and moderator. I haven't cut it and am keeping it as a rough specimen. But Conny may know about the lapidary treatment and hopefully he'll respond if he sees this thread.

I noticed that another Forum member, Hans Durstling, elsewhere suggested polishing using Colgate toothpaste on a soft cloth as in polishing amber, since jet's about the same hardness. I've successfully polished amber on my Genie machine from Diamond Pacific, shaping carefully on a 220 metal diamond wheel, then sanding and polishing with 600, 1200 and 3000 Nova resin-bonded diamond wheels. I'd use water for a lubricant since my jet specimen seems porous and likely would absorb oil.

Jet's a form of coal or pre-coal and seems to vary considerably in hardness and density. John Sinkankas, in his venerable "Gem Cutting: A Lapidary's Manual" (2nd Edition) says it's tough and takes a "fine" polish. He suggests shaping with steel tools and abrasive papers and polishing on cloth, felt or leather with cerium oxide, tin oxide or Linda A. He says leather buffs are preferable.

Good luck!

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 Post subject: Re: Information Requested Concerning Jet
PostPosted: Fri Sep 01, 2017 12:16 am 
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ROM wrote:
I have a small specimen of jet given to me by Conny Forsberg FGA, a Forum member and moderator. I haven't cut it and am keeping it as a rough specimen. But Conny may know about the lapidary treatment and hopefully he'll respond if he sees this thread.

I noticed that another Forum member, Hans Durstling, elsewhere suggested polishing using Colgate toothpaste on a soft cloth as in polishing amber, since jet's about the same hardness. I've successfully polished amber on my Genie machine from Diamond Pacific, shaping carefully on a 220 metal diamond wheel, then sanding and polishing with 600, 1200 and 3000 Nova resin-bonded diamond wheels. I'd use water for a lubricant since my jet specimen seems porous and likely would absorb oil.

Jet's a form of coal or pre-coal and seems to vary considerably in hardness and density. John Sinkankas, in his venerable "Gem Cutting: A Lapidary's Manual" (2nd Edition) says it's tough and takes a "fine" polish. He suggests shaping with steel tools and abrasive papers and polishing on cloth, felt or leather with cerium oxide, tin oxide or Linda A. He says leather buffs are preferable.

Good luck!


Appreciate your reply concerning Jet an its handling. I've come to the conclusion that using water, just to be safe and eliminate the possibility of any oil absorption. Not all that familiar with the Genie machine but , if I may, ask what you use as a coolant when you cut and/or process the amber? Thanks again for Taking the time to post a reply.


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 Post subject: Re: Information Requested Concerning Jet
PostPosted: Fri Sep 01, 2017 11:49 am 
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I use nothing but water as coolant when grinding and polishing. I'd recommend water also for mechanical sawing, as you mentioned.

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 Post subject: Re: Information Requested Concerning Jet
PostPosted: Mon Sep 04, 2017 10:34 am 
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ROM wrote:
I use nothing but water as coolant when grinding and polishing. I'd recommend water also for mechanical sawing, as you mentioned.


Do you find it necessary to add a rust preventing agent to your coolant when cutting, grinding or polishing? If so, what would you suggest? Thanks for taking the time to update as I don't have that much experience using plain water by itself.


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 Post subject: Re: Information Requested Concerning Jet
PostPosted: Mon Sep 04, 2017 12:07 pm 
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Ivanhoe wrote:
ROM wrote:
I use nothing but water as coolant when grinding and polishing. I'd recommend water also for mechanical sawing, as you mentioned.


Do you find it necessary to add a rust preventing agent to your coolant when cutting, grinding or polishing? If so, what would you suggest? Thanks for taking the time to update as I don't have that much experience using plain water by itself.

It's hard to make a recommendation not knowing exactly what equipment you use. The grinding/polishing machine I use is designed for the use of water as a coolant as are most that I know of. Mine is a Genie made by Diamond Pacific. Many of the parts exposed to water are made from hard plastic: http://www.diamondpacific.com/thegenie.html

My trim saw is not designed for water as a coolant so I do use a product called Lube Cool as an additive. I don't know where you're located but I get mine from Johnson Bros. Lapidary, johnsonbrotherslapidary.com/ It appears to be some sort of water soluble oil but wpes off the hands easily and in the year or so I've used it I haven't observed any rust.

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 Post subject: Re: Information Requested Concerning Jet
PostPosted: Mon Sep 04, 2017 2:00 pm 
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ROM wrote:
Ivanhoe wrote:
ROM wrote:
I use nothing but water as coolant when grinding and polishing. I'd recommend water also for mechanical sawing, as you mentioned.


Do you find it necessary to add a rust preventing agent to your coolant when cutting, grinding or polishing? If so, what would you suggest? Thanks for taking the time to update as I don't have that much experience using plain water by itself.

It's hard to make a recommendation not knowing exactly what equipment you use. The grinding/polishing machine I use is designed for the use of water as a coolant as are most that I know of. Mine is a Genie made by Diamond Pacific. Many of the parts exposed to water are made from hard plastic: http://www.diamondpacific.com/thegenie.html

My trim saw is not designed for water as a coolant so I do use a product called Lube Cool as an additive. I don't know where you're located but I get mine from Johnson Bros. Lapidary, johnsonbrotherslapidary.com/ It appears to be some sort of water soluble oil but wpes off the hands easily and in the year or so I've used it I haven't observed any rust.


Your explanation serves to clear up this matter for me. I'm familiar with the additive called Lube Cool. I've used it in my small trim saw an it works satisfactorily as you pointed out. My cab machine is Lortone Beaver that I use 4 grinding wheels. That would require a coolant using a rust preventative.

I used Lube Cool or a product called Crystal Cut as a rust preventative & lubricant. I'm not sure if it is still available but it does work rather nicely as does Lube Cool. I store my steel shot using Crystal Cut.

Just a thought .... Not sure but what you shared I think Lube cool or Crystal Cut should work to cut that piece of Jet?? Without running the risk of it absorbing and/or staining the Jet. Located in Pa. Thanks again for your replies. IV USAF 62-66


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 Post subject: Re: Information Requested Concerning Jet
PostPosted: Mon Sep 04, 2017 2:48 pm 
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I was going to edit my earlier post with this:

I wouldn't use anything but plain water for sawing jet. Many cutters use water to saw stones that might be harmed by oil, but make a practice of wiping down the entire saw and blade after each use with water to prevent rust.

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