polishing cut glass

**nicko0** · 04-07-2013, 03:39 PM

so im cutting glass with a wet saw and a pretty good purpose built blade. the cut has the surface roughness of a gong joint.

its too rough to flame polish as is.

can i kiln heal it and how?

can i polish it smooth enough to finish it in the flame?

how fine and what methods can i use?

**puddletown** · 04-07-2013, 04:37 PM

get a lap wheel?

how often are you going to be doing this?

is it worth buying a tool to do it, or is it an one time thing?

**nicko0** · 04-07-2013, 05:03 PM

more than one time. probly gonna buy a flat lap. but id like to just proof of concept and learn a bit on the way.

so... lets say on a lap wheel, how fine do i gotta go to be able to flame polish it the rest of the way.

im really hoping there is a way to use a kiln, i doubt 1700 is hot enough.

maybe place the cut glass facing the element like an inch away at full speed from cold to 1700?

**SexualHarassmentPanda** · 04-07-2013, 06:01 PM

my first job in a hot shop was grinding and polishing glass, with hot Glass it is not always possible to fire polish, i am guessing what you are saying is that if you firepolished it, it would look like shit. lets say i was polishing the bottom of a paper weight. first i would grind it flat on a wheel using either 80 or 120 i cant remember silicon oxide, when it was flat i would bring it over to a piece of thick plexiglass and put down more wet silicone oxide maybe 160, this was a long time ago, then "sand" it on the plexiglass in finer twice... then its real smooth.... then i take it to a felt wheel and apply cerium oxide and polish to CLEAR.

**nicko0** · 04-07-2013, 06:05 PM

hmmmm. dont like the sound of that too much. i definitly dont want to have to polish it to the point of clear. its gotta eventually go in the flame too.

**SexualHarassmentPanda** · 04-07-2013, 06:13 PM

im sure there are other ways, thats just pure coldworking.

**puddletown** · 04-07-2013, 06:29 PM

Im not sure what grit you have to take it to, but after a certain point, you can flame polish without seeing any scuz from the cut

**nicko0** · 04-07-2013, 06:37 PM

cool thx. ill be buying a variety of wet sand paper tomorrow and see what works.

and if its efficient.

**SexualHarassmentPanda** · 04-07-2013, 06:54 PM

if no one can give more exact numbers id say 800-1200 final. before flame

**Greymatter Glass** · 04-07-2013, 07:59 PM

There's Aluminum Oxide and Silicon Carbide (SiC)... Silicon Oxide is glass. SiC is preferable because it's harder and more abrasive.

You can use sheets of the wet/dry black emery cloth from a hardware store, or hand lap with SiC grit purchased at rock / hobby / toy stores for the little rock tumblers....

Figure out what grit your saw blade is, MK / BD 303 blades are about 160 grit IIRC.

You CAN fire polish from a very rough grit if you do it slowly, let the heat soak in and bring it up in the back flame then dance it in and out... it takes along time, and you'll get a "scuz" if you look close, but it's essentially fire polished.

if you want an optically clear fire polish you have to get up to at least a 600 grit finish, and follow the same above steps.

You can, if you need it to be true optical quality and completely flat, hand lap your work on sheets of cheap float glass with loose grit and water, then move to diamond pre-polish pastes, and finish with cerium oxide on a felt pad. If you go that route, get several sheets of float glass, only use one size grit per sheet, and keep an eye on it, the float glass will wear away faster than the boro, especially on the coarser grits.

**Greymatter Glass** · 04-07-2013, 08:02 PM

Originally Posted by SexualHarassmentPanda

if no one can give more exact numbers id say 800-1200 final. before flame

I flame polish from a 1200 grit diamond resin bonded disc and it works flawlessly, someone else I know fire polishes @ 600 grit and has amazing results as well... I've tried 400 and get scuzz.

**Greymatter Glass** · 04-07-2013, 08:04 PM

Originally Posted by douglasbloer

im really hoping there is a way to use a kiln, i doubt 1700 is hot enough.

maybe place the cut glass facing the element like an inch away at full speed from cold to 1700?

All that will do is devitrify and eventually phase separate the glass. I don't think there's a reliable way to kiln polish boro with a normal kiln. One could be made for the purpose.... but not just your normal annealing kiln.

**nicko0** · 04-07-2013, 08:38 PM

yay i love u guys!

really? 600 grit i thought that would still be way too coarse.

black emry cloth, hobby store, polish, check thx.

800 to 1200, ok

ill post results as soon as possible

ps im cutting with a result multi purpose blade from http://www.hisglassworks.com/cart/Re...l#.UWI7PteNNAs

**nicko0** · 04-07-2013, 08:43 PM

so i placed the cut glass within an inch of the elements in the top of my kiln. ramped full speed to 1700.

2 of the five pieces smoothed out very nicely and could be used in the flame. three of them had areas that were still not melted in. they appeared to be patterned from the blade, not areas that didnt get hot enough long enough, tho i do believe a little hotter a little longer will do the trick. maybe cycle them twice. wish i had a clamshell for fusing at higher than 1700 degrees.

do u think cleaning them better than a quick rinse would improve results? even using the healing kiln method?

**somewhere** · 04-07-2013, 09:27 PM

Originally Posted by douglasbloer

so i placed the cut glass within an inch of the elements in the top of my kiln. ramped full speed to 1700.

2 of the five pieces smoothed out very nicely and could be used in the flame. three of them had areas that were still not melted in. they appeared to be patterned from the blade, not areas that didnt get hot enough long enough, tho i do believe a little hotter a little longer will do the trick. maybe cycle them twice. wish i had a clamshell for fusing at higher than 1700 degrees.

do u think cleaning them better than a quick rinse would improve results? even using the healing kiln method?

600 grit works fine.

The problems you are having is two fold course cut and contamination. You can get around the course cut but the contaminants will cause bubbles and scuzz even if you do torture you kiln to death. To avoid contaminants you need to take it to a fine grit less course less room for contaminants. It's either that or clean with acid. A good blade is where you should start and lots of fresh water don't recycle rinse well after the cut.

**nicko0** · 04-07-2013, 09:48 PM

thx. ill stop recycling.

ooh i didnt really think about the extra wear on the kiln.

thx

keep it coming

**Greymatter Glass** · 04-08-2013, 11:19 AM

yeah... I would wash them with water then alcohol, maybe some acetone if you've got a lot of greasy tools around the shop that might get on the glass? Microfiber towels or other lint-free wipes for drying.

**sasch74** · 04-08-2013, 02:35 PM

Alcohol and a soft brush will do, also take your time when you get it into the flame, soak in the heat gently. Everything will be just fine!

HF again would speed up that process tremendously, even a very thinned out solution (10-15%), but as always I wouldn´t recommend having this stuff in your shop and I´m sure many here will agree.

**sasch74** · 04-08-2013, 02:35 PM

Alcohol and a soft brush will do, also take your time when you get it into the flame, soak in the heat gently. Everything will be just fine!

HF again would speed up that process tremendously, even a very thinned out solution (10-15%), but as always I wouldn´t recommend having this stuff in your shop and I´m sure many here will agree.