polishing glass

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

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.

[www.rocktumblinghobby.com]

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.

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

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.

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

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

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

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.

[rocktumblers.blogspot.com]

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

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

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).

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.

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

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?

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?

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.

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.

would it be possible for you to share with me how you polish to a shine the tumbled glass

thanks

gail

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.

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