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polishing glass

Posted by gail  
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gail August 29, 2006 04:07PM
hello fellow rockhounders

the glass is low quality.just shards of wine bottles and water bottles......
i tried aluminum oxide and then a wash with some dish detergent.using rotary tumblers

the finish continues to be dull........not the glossy finish of unprocessed glass.

i will appreciate the solution to this ( no pun intended)........

yours happily in the green playground

gail
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David Von Bargen August 29, 2006 04:15PM
You normally need to run through as series of grinding stages with finer grades of grit and then polish with an extremely fine abrasive (polishing compound) such as tin or cerium oxides.

http://www.rocktumblinghobby.com/
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William G. Lyon August 30, 2006 08:27PM
Gail,

I assume your problems are mainly in the final polishing stage of tumbling, and that you are getting pretty good results up to that point. You might want to add some plastic beads to prevent your glass from self-scratching while tumbling in the finer stages. Other stuff like walnut shells can work as a buffer in a similar fashion. Some folks add sugar to increase the viscosity. If you google around the internet, you might want to look up the specific tumbling recipes given for polishing apache tears, since this is a pretty good (somewhat harder) analog for bottle glass. (See Bob's Rockshop, Archives)

Your tumbling load should consist exclusively of glass fragments with the same hardness; obviously, you can't mix in harder stuff like agate, and expect the glass to polish. Your tumbler has to be very, very, VERY clean before using it for softer materials like glass. You might also want to try one of the softer polishes like Cerium Oxide for glass ($$$). After that, a final burnish with Ivory flakes, etc.
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gail August 31, 2006 03:29AM
thanks william i might give the cerium oxide a try........
since i posted i read that if your tumble them just with pellets and water then the finish is not frosty like beach glass but keeps the original finish.........just water...sounds unlikely but i'm also going to give it a try.........so in other words .........i'll just tumble freshly broken glass with plain water and pellets.......i'll post the results of this latest idea

thanks again

rocky
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David Von Bargen August 31, 2006 12:58PM
In tumbling (like other rock polishing) you use a coarse grit to shape the stone and get rid of sharp edges. You then go to increasingly finer grits to eliminate the scratches created by the previous step in the grinding. You use extremely fine abrasive (polishing powder) to sand out the scratches created by the fine sanding.
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gail August 31, 2006 06:02PM
i know this david i have done it repeatedly.......but i read that glass, water and plastic pellets will eventually smooth the glass edges.......it sounds unlikely.....but i still going to give it a try........nothing to loose but mechanical time.......

thanks for trying to lead me straight

rocky
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Anonymous User August 31, 2006 06:15PM
Gail,

I help people polish glass everyday.

If you want to call me I would be glad to give you detailed instructions. I am to slow of a typer to type it all out.

I have been doing tumbling for over 30 years and have done hundreds of pounds of glass.

Rick Dalrymple
801-355-7952
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gail September 01, 2006 05:48PM
thanks rick........but could you just tell me via the post here...........yes or no to the idea of a straight water /pellet for grinding and polishing in 1 step.......have you heard of this or tried it..........

yeah ..........a master glass polisher....just who i wanted to talk to.......
thanks for taking the time to post

rocky
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Anonymous User September 05, 2006 03:45PM
Hi,

I have the directions on my blog for making beach glass. If you are trying to polish to a high gloss you just keep going through the steps using Tin oxide for the polish with plastic pellets.

Make sure the barrel is 3/4ths full with the glass and plastic pellets. When you add the water replace 1/2 of it with corn syrup. This thickens up the solution, slowing down the process, which keeps the glass from scratching itself up. If you have 3/4ths full with just the glass, remove some and put in the pellets when you get to the polish stage.

You can also skip the first grit as it leaves deep pits in the rock that take a long time to get out.

If you are doing flat pieces you MUST add small (BB size or platic pellet size) pieces of glass to work their way between to polish the face of the slabs.

http://rocktumblers.blogspot.com/2005_11_01_rocktumblers_archive.html

Do each stage of the process for 3-5 days checking every day once you get to the polish stage.

The polishing stage can take up to 2 weeks alone to get that gloss. If everything has gone right it should take about 5-10 days in the polish.

Rick
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joanne April 30, 2007 02:42AM
I was thinking about using metal shavings in my tumbler to take the sharp edges off my glass. Will this hurt me or help me. I was also thinking about using grit in sand blasting
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David Von Bargen April 30, 2007 10:01AM
Depending upon the type of metal, the metal will most likely be softer than the glass. If you have a lined tumbler, there is a pretty good likelyhood that the metal shavongs will stick in the side of the tumbler and will be a pain to clean up.

For using grit in sand blasting, make sure your nozzle was designed for the appropriate hardness of your sand agent (it can erode the nozzle faster).
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Joanne May 10, 2007 01:37AM
Hi, I have tried using the grit(black beauty) in the tumbler. It breaks down quickly. I havent seen the results of the people using just water for tumbling. I have the same problem. I am breaking blown glass pieces and i lose the shine. I am just tryng to get the sharp edges off to make jewelry.I was thinking about tumbling with glass beads used in blasting.
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Joanne June 03, 2007 10:38PM
Hi, I dont remember if i have emailed you before, sucks to get old . Anyway.I want to tumble blown glass pieces. I am trying just water. The last batch i did, my glass looked dull, it lost it's shine.Have you ever just used water
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Rock Currier June 08, 2007 06:14AM
Gail,
I have seen some glass that has been polished quite effectively with hydrofluoric acid, but have never done it myself except to small portions of my eye glasses. Also hydrofluoric acid is a really scary acid to work with and let me assure you, from personal experience, that unless you have been instructed in its use, you should not get involved with this critter. If you have large quantities of glass to polish you may wish to explore this possibility, but if you have just a few pounds to polish, you should probably keep on track with the lapidary option.

Has anyone here had any experience with polishing glass with HF?
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Paula Stalker July 16, 2007 05:26PM
I am absolutely new to a rock tumbler. I bought used with no instructions. I want to make "beach glass"and I could use a bit of advice like how big can the shards be? Can they be of different sizes or all the same? I have a 3 lb. tumbler. What do I need to start and finish to get that smooth cloudy look of beach glass?
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David Von Bargen July 16, 2007 07:27PM
The first grinding stage is the one that does most of the shaping of the piece. Further stages are finer asnd finer grades of grit that are used to remove the scratches from the previous stage. You can have some variation in size, but if you have a bunch of real small pieces (say 1/4 inch) and some 1-2 inch pieces, the smaller ones will be worn away before the larger ones get smoothed.
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Norm Robar December 25, 2007 09:52PM
I tumble and polish mostly old glass......100 years or older. I smash it into approximate sizes I wish for a finished product. You cannot make beach glass by tumbling, but can make a reasonable duplicate. To be honest, you should identify it as faux beach glass. Good faux beach glass will require a good magnifying glass to tell it from the real thing. I use slightly coarse sand and salt water as a tumbling medium, after having removed sharp edges, etc, with coarse grit. The glass I tumble to a fine polish takes a lot of experimentation, as the tumbling processes for stones will not provide the clear finish. The glass shards I use vary in thickness from normal bottle to over one half inch.
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gail December 27, 2007 04:13AM
would it be possible for you to share with me how you polish to a shine the tumbled glass

thanks

gail
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John Truax December 29, 2007 06:53PM
Glass takes a long time to polish ... I have waited 6 weeks to get obsidians to shine in a vibrating tumbler using Rapid Polish and no plastic beads.



Edited 1 time(s). Last edit at 12/29/2007 07:06PM by John Truax.
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Ray Hill December 30, 2007 02:39AM
I read all of these and was intrigued...

I wonder out loud, if I read the queries correctly?...did you have pieces of blown glass and tumbled them to get rid of the sharp edges, BUT, were disppointed that the process took away the original shininess of the glass pieces...??
if all you want to do is take away the sharp edges, but keep the original shininess, then may I suggest that you apply gently increasing pressure of gas to a blow torch and run it back and forth along those sharp edges. it will melt the sharpness away and yet maintain the original shininess and essential shape of the original shards..
It can't hurt to try it out on a few small pieces to find out the right temperature and pressure of gas that melts and softens the edges without melting the entire piece...
Just a thought.
Ray
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ss January 06, 2009 02:30AM
Hi everyone!
I just accidentally found your blog discussing polishing beach glass.
New to this. I have a new tumbler (never have used it...not sure what to do)
I would like to just put some shine on the beachglass I have found. Any EASY and relatively
simple ways to do this?
Thanks for your help.
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Rock Polishing February 13, 2009 05:30PM
If you check out my rock polishing blog, you'll find all the answers u need there
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bhavin January 27, 2010 01:58PM
Please anyone can tell me what are the steps of polishing glass beads?
I'm using polishing machine which is simply rocking rubber wheel i need to know what are the steps of polishing and what are the chemicals used in polishing in every step the right quantities to be used. should I add any smaller size round beads to give round effect as a result?
please any good information or advice will be appreciated
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bhavin January 27, 2010 01:59PM
Please anyone can tell me what are the steps of polishing glass beads?
I'm using polishing machine which is simply rocking rubber wheel i need to know what are the steps of polishing and what are the chemicals used in polishing in every step the right quantities to be used. should I add any smaller size round beads to give round effect as a result?
please any good information or advice will be appreciated
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Jamey Swisher January 30, 2010 04:10PM
The best way to polish the glass in the final stage is to add in plastic pellets and use optical grade cerium oxide as it is the best polishing medium for glass. The key is you also want to have a nice smooth pre-polish on the material before going into the polishing stage.

------------------------------------------------------
Registered Gemologist
Research Gemologist
Rockhound/Cutter/Collector
Club President/Owner
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Heidi April 26, 2010 05:42PM
Hi,

Bought a 60lb plus piece of glass rock. It is leftover glass from windows, they sell to tourists. Want to sand it up and polish it, and set it by my swimming pool.

Any advice ? We have been using a drummel with a fine stone for the edges and a sandpaper tip for the surface. Seems to scratch it up. HELP!

Thanks, Heidi
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Donald Slater April 30, 2010 04:35PM
As you have seen, if you ask 50 people the best way to tumble polish you will likely get 50 different answers. Tumbling is an art and everybody has found a way that works best for them, so it is a matter of experimenting and finding what works best for what you are trying to polish. I finally found a recipe from someone that was an old hand at tumbling. I tried a dozen things to tumble obsidian and never could get a good polish until I tried using: ground corncob, broken tempered safety glass with a few shavings of Ivory Bar soap on the final stage. I do the first 3 steps as you would anything else. I start the broken safety glass (the stuff you get when someone breaks you brand new patio sliding glass door with a baseball smiling smiley), in the first step and keep it all the way to the end, adding more after the first and second step to keep the volume up. It breaks in nice size angular pieces and works great as a tumbling media. The hardness is just slightly harder than most glass so is durable without beating up the glass. I actually use it instead of plastic pellets, which I hate, even with agate. I put enough ground corncobs to make a thick mushy slurry. You can experiment with the amount depending on your type and size of your tumbler. The corncob works well as a carrier for the polish and as a cushion to keep the glass from banging and chattering against each other. One of the most important things, especially with a rotary tumbler is to keep the barrel about 3/4 full. If the volume is to low you don't get enough interaction and the glass has too much space to bang against itself. I sometimes will do a final burnishing step with just fresh corncob, the safety glass and Ivory soap if needed. I hope I have helped and not added to the confusion. If you have any more questions you can send a PM or ask here. Good luck
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Donald Slater April 30, 2010 06:33PM
I forgot to answer a question posed by Rock earlier about polishing glass with HF. I have always had a love of glass and use to cut and polish slag glass into various obliques shapes and thought about trying to use HF for the polish. Many years ago I visited several glass cutting factories in Ireland and found that virtually all if not all of the leaded glass pieces manufactured these days is acid polished. I think it is a shame because it lacks the really fine sparkle that the old pieces had which were hand polished. I asked at several factories and as expected they are secretive of the exact process but I found out that the always first run the pieces through a Sulfuric Acid bath to remove any oils or other contaminates. They wouldn't tell me the concentrations of the acids used but I was told that Acid polishing with HF only works if there is a sufficient percentage of lead oxide which I think is above 20% but I don't remember. Before I knew this I had a brilliant idea of using HF to polish Apache Tears but it wasn't that brilliant. It produced an a tektite look alike which was interesting but not polished. I don't think I ever tried HF on my slag glass. If I did it didn't work because I stuck with my original method. Being a geochemist I have worked with lots of acids and I would not recommend using HF to anyone that is not trained and very experienced with chemicals. It is the one I treat with the UTMOST care. It is very nasty and dangerous.
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LapidaryMadness August 04, 2010 01:04PM
Another good site on rock polishing is www.rock-polisher.com

Rock Polishing Wrote:
-------------------------------------------------------
> If you check out my rock polishing blog, you'll
> find all the answers u need there
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Jamey Swisher August 05, 2010 03:24AM
I almost forgot, another method to polish glass, is of course, flame polishing. Not as good as a well done lapidary polish IMHO, but still works nicely and is much easier, and faster as well, to do.

------------------------------------------------------
Registered Gemologist
Research Gemologist
Rockhound/Cutter/Collector
Club President/Owner
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Jenny April 11, 2012 05:21PM
Hi fellow glass inthusiests,
My inquiry is: I do art and would like to do a glass mosaic on a French Glass Dividing Wall I have between my kitchen and living room. I have not worked with to much glass when it comes to art but I have broken up colored glass pieces(from bottles, vases, etc.). I do not own a tumbler to smooth out my broken glass and it is far to much work to individually sand hundreds of small pieces with sand paper. I dont have an oven to heat up to 2100 degrees or what have you. I have a blow torch, oven, microwave, somewhat regular household items. I want to do it right, but when the muse calls, I like to jump into it. Any suggestions other then to go out and buy what I need. I just want to round off edges on broken glass without taking 100 years to do so!
Thx- Jennifer
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Tim Jokela Jr June 05, 2012 06:57PM
Let me get this straight.

You do not want to individually grind and polish each piece.

You do not want to buy a tumbler.

You want it done right, and right now, without wasting any time.

May I suggest trying magic?

If that doesn't work, make a very modest investment in a decent tumbler and range of grits. It really is a very, very simple process, and glass is soft so it won't take that long.

This website has everything you'll ever need to know about tumbling:

http://rocktumblinghobby.com/
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Amir C. Akhavan June 05, 2012 08:35PM
If all you want is to avoid being cut by slightly rounding off the edges of the glass shards, you could try putting the glass pieces in boiling water for some time.
This is supposedly rounding off the edges by dissolution of the glass.
Maybe add some baking soda, as alkaline solutions will speed up the dissolution.

I've seen that in a TV science show many years ago.
It was said to be a technique occasionally used by people who show off walking on glass sherds with their naked feet.

The look of the glass sherds is basically unaffected.
So this is no replacement for tumbling.
You might give it a try.
I have not tried it myself, so don't ask me for details.
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Linda Carnicelli February 19, 2013 09:38PM
I have some blueberry quartz beads that need to be polished to give me a nice shine on them. any suggestions?
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Rock Currier February 20, 2013 09:01AM
I am not familiar with "blueberry quartz". Could you post a picture of them or tell us something of their origin? Are you sure the material is quartz?

Rock Currier
Crystals not pistols.
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Barb Murrin May 02, 2014 02:30AM
I'm also interested in being able to smooth out glass edges for mosaic use. (Think it would be a good way to use up glass scraps that would otherwise be discarded.) A couple of questions:

- What tumbler would you recommend for this?
- Ground corncobs - Do you let the cobs dry and then grind them up somehow, or can you buy them ground and ready to go? If you grind them yourself, how do you go about it?

Thank you for your assistance.

Barb
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Rock Currier May 02, 2014 12:27PM
Jenny,
How large are the glass pieces you want to "round"? If they are too large, putting them in a tumbler will cause them to break and chip each other. Putting ground up corn cobs in the tumbler will "cushon" them from bashing against each other to some extent. If you are going to round them you will have to put in an abrasive media that will grind away the sharp edges, but it will also dull the shiny surface of the glass and leave you with a mate finish. To get them shiny again? you will need to use progressively finer grits and finally a polishing powder, being careful to clean them and your tumbler between each step to make sure that you remove all the abrasive media from the previous step. Glass is real easy to work with. I might suggest you use a sanding disk and you manually sand the edges a little bit to break the sharp edges, if that is what you want. If you need the edges polished, you can pretty easily polish it using a leather or felt buff and something like tin oxide or aluminium oxide after a quick once over with 600 grit paper. Depending on the degree of roundness you want you might even be able to break the edges enough with a 600 grit disk.

Rock Currier
Crystals not pistols.
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Ubermut January 09, 2016 06:26PM
Water diluted Hydroflouric acid along with Sulphuric acid in the right proportions is excellent for polishing glass but is EXTREMELY dangerous. Anyone using it should wear fully protective gear and work outdoors - with double gloves. Check the forums and you will read of fatalities with small amounts getting on the skin. Do not attempt to use it if you do not first purchase Calgonate (Calcium Gluconate) for First Aid. It does not just give you a skin burn. Once on the skin it invisibly travels deep to the bones and alters hour body calcium levels leading to a heart attack. Spill a cupful in your arm or leg can be fatal - not straight away - and even if you jump immediately into a swimming pool or run a bath to soak in it. It is now illegal to either purchase or store HF in the UK without a license. I am still working on an alternative lapidary means of gaining a highly polished finish. Unless I can find one my days of glass polishing are now over.
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