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Offline bushman

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Glass?
« on: June 24, 2011, 04:49:44 am »
Has anyone ever takin some rocks and heated them up to get glassy slag to make something like Obsidian before?
Bushman
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Offline Tower

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Re: Glass?
« Reply #1 on: June 24, 2011, 09:56:27 am »
Never heard or seen it before. I don't know if it's possable. Lava is what 2000 deg?
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Offline JackCrafty

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Re: Glass?
« Reply #2 on: June 24, 2011, 11:41:33 am »
Nope, never seen it done.  Much easier, and probably cheaper, to just go buy the obsidian.  There's millions of tons of it out there.
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Where's Rock? Public Waterways, Road Cuts, Landscape Supply, Knap-Ins.
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Offline aaron

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Re: Glass?
« Reply #3 on: June 24, 2011, 12:40:14 pm »
yes, i have melted glass for knapping purposes. i used the type of glass used in "fused glass" . melted it in a kiln at the glass store where they teach glass fusung,. the stuff knaps like obsidian, but sometimes the different colors don't blend completely. lots of people have done this. glass stores sometimes have broken pieces to give away. the slab in the pic was made by taking many broken chips and melting them in a terra cotta flower pot- the glass oozed out the bottom into a pancake.
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Ilwaco, Washington, USA
"Good wood makes great bows, but bad wood makes great bowyers"

Offline triggerfinger

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Re: Glass?
« Reply #4 on: June 24, 2011, 01:12:50 pm »
 that answers my queastion too
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Offline bushman

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Re: Glass?
« Reply #5 on: June 24, 2011, 05:44:59 pm »
I didn’t think it would be very cost effective but was wounderin if anyone ever tried it before. I have heard of people knapping the glass slag from different metals that have been smelted before.
Aaron: Nice lookin slab of glass. How did you collect the glass when it oozed out the bottom of the terra cotta flower pot? What did you use as a heat source to melt the glass?
Bushman
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Offline Bill Skinner

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Re: Glass?
« Reply #6 on: June 25, 2011, 12:19:59 am »
I don't know if he still does it, Craig Ratzat used to make an American flag blank, he would set the glass up and saw it.  There are quit a few floating around.  Bill
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Offline aaron

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Re: Glass?
« Reply #7 on: June 25, 2011, 01:19:08 am »
bushman, i should clarify...
the pic is of a slab made by Jeff Dixon (i think). He uses a glass fusing kiln- like a ceramic kiln, a modern one. he catches the puddle in a terra cotta saucer with some kind of white powder coating it. The pic (above) shows emory coons about to turn it into a butterfly. sorry no pics of the butterfly!

most of the "art" glass i have knapped was "slag" pieces ;eft over after glass blowing. have had mixed results. different glasses have different ... i dunno what it is... each is assigned a number, perhaps having to do with melting point .... they don't always knap equally, that it, fractures studder as they pass from one to another, leading to ripples and hinges.
i think complete melting and tempering is the key.

the pieces i have done myself were done from cutoffs from a window in my house- i took the cutoffs, cut them into equal sized pieces, stacked the pieces and put the stack in a glass kiln. they melted to a 3/8 inch slab of swirly blue, white and clear.  i knapped the result into a clovis like shape but darned if i can find a pic. here's a pic (below) of the window, anyway.
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Ilwaco, Washington, USA
"Good wood makes great bows, but bad wood makes great bowyers"

Offline aaron

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Re: Glass?
« Reply #8 on: June 25, 2011, 01:25:05 am »
trigger finger... ha ha.. i was reading your post and this one and when i wrote my reply above i was thinking i was replying to your post more than this one . sorry.
as for the original question of melting rocks... well THAT would be bad ass! I have some friends who have tried melting obsidian debitage as part of art pottery fired in an "anagama" kiln (wood fired dragon kiln). the results have been very bubbly and unknappable,.
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Ilwaco, Washington, USA
"Good wood makes great bows, but bad wood makes great bowyers"

Offline rockbob

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Re: Glass?
« Reply #9 on: June 25, 2011, 06:05:01 pm »
Lets see what you made  from that round color slab.
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Offline rockbob

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Re: Glass?
« Reply #10 on: June 25, 2011, 06:24:01 pm »
Glass point from fused  glass
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Offline Lee Slikkers

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Re: Glass?
« Reply #11 on: June 27, 2011, 02:04:47 pm »
Wow, this some beautiful and interesting info...need another pursuit like a hole in the head but it IS something I need to learn so I can hunt with a bow, arrow, head I have made myself.  So many cool ideas and possibilities!
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~ Lee

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"The last word in ignorance is the man who says of an animal or plant: 'What good is it?"
— Aldo Leopold
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Offline triggerfinger

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Re: Glass?
« Reply #12 on: June 27, 2011, 05:19:47 pm »
wow thats a beautiful point!   how sturdy are those glass points, how much use do you get from one before it ruined given it doesnt smack rock
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Offline rockbob

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Re: Glass?
« Reply #13 on: June 27, 2011, 10:40:35 pm »
Triggerfinger- I think your supposed to hit the animal and not the rock.
 actually its only gonna last one time.
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Offline bushman

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Re: Glass?
« Reply #14 on: June 28, 2011, 04:19:14 am »
Quote from: aaron on June 25, 2011, 01:25:05 am
trigger finger... ha ha.. i was reading your post and this one and when i wrote my reply above i was thinking i was replying to your post more than this one . sorry.
as for the original question of melting rocks... well THAT would be bad ass! I have some friends who have tried melting obsidian debitage as part of art pottery fired in an "anagama" kiln (wood fired dragon kiln). the results have been very bubbly and unknappable,.

Thanks for the info Aaron. That window looks like it would have made a really nice point. When I was doin a little blacksmithin a few years back I accidently dropped some Borax into the forge, it turned into a type of glassy slag that if it was bigger looked like it might have been knappable. Will have to give it a try again but not in the forge this time. For rocks I think they would have to be powdered up like flour before you can try and melt them. One it will take less heat and two I was thinking that the gasses would release and not stay in the slag. Maybe have to get some really fine silica sand and give it a try or some really fine tailings from a mine. The slag off of a submerged arc weld is what got my think about it because its got silica, quarts and a few other things in it as well as different metals but it turns into a glassy slag.
Rockbob, supper cool point, like the colours in them. Works of art or are you goin to hunt with them?
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