Grinding / polishing murrini - how much is enough?

[Paul Thompson]

I cut some murrini using a tile saw. That obviously left a nasty, rough surface. I think it would be a good idea to grind at least one face before I use them. Eventually, I plan to torch the murrini plus some cane before I roll the mess onto a bubble (the pastorali is too unwieldy & heavy for anyone smaller than da Arnold).

What's enough grinding / polishing of the murrini to get a surface that will not exhibit the tile saw scratches? I'm mostly worried about the face that will be on the bubble -- I think I can fire polish the outside surface (???) but then if I can save five or ten minutes of glory-hole time by grinding both faces, I up for it. Tanks sin nad vants.

[David Patchen]

Good questions. Based on my own trial and error, I've found murrine cut on a saw won't fire polish nicely. Even if you get it ripping hot, it will still look dirty from all the crap that's on the rough cut surface. (You shouldn't get murrine ripping hot anyway, but that's another issue). What I've found works is a 100 grind on the murrine that's on the outside--this lets them flame polish nicely. If the inside is cut as well, I do an additional polish to 400 using a SiC belt sander and it's perfectly clean. You can cheat by going 100 on both sides and once it's hot you hit the bubble side of the murrine with MAP gas to flame polish it before you pick it up. Works ok if you only have a couple murrine that need it. Taking it to 400 only takes 20 seconds longer in the cold shop, so that's what I do.

I've seen people take the murrine to 100 grit on both sides, then after it's fused and flame polished on one side, they flip the murrine over. I think this can create additional issues that aren't worth the time you might save in the cold shop. You might like it though.

[Kenny Pieper]

Richard Ritter has done this for quite a while and this is what works for him. He cuts the murrine with a saw blade that has a very thin curf so as not to loose much material and 220 grit diamond for a smooth surface. With the 220 diamond surface the glass just needs to be cleaned well. Before picking the pieces up out of the kiln he will give then a bit of torch polishing.

[Eben Horton]

I use a chopper made by Roberto Dona. No cleaning needed :)

[David Patchen]

I chop 99% of mine with a chopper made by...me. Agree--clean chop the best way to go.

Kenny, funny you mention Richard Ritter's method as I just bought a thin diamond lapidary blade for cutting murrine that's too large to chop. I've only made a couple test cuts, but it does seem *much* finer cutting than the regular diamond blade that leaves a rough surface and takes out more than 1/8" of material. I don't know if it's 220 or not, but I was pretty excited about how clean a surface it left. Haven't tried picking up anything it's cut yet, but it looks encouraging.

[Dave Bross]

I haven't done it, but I suspect you could tumble them in a rock tumbler with sand and they would be good to go.

Perhaps a quick fire polish afterwards on the pastorelli to clean up the side going against the glass. The outside should clean up first pass through the glory.

[Paul Thompson]

I use a chopper made by Roberto Dona. No cleaning needed :)

Agreed, fastest and easiest solution, just not available. But let me tell you (apologies to Lee Hays & Pete (Seeger))
if I had a chopper
I'd chop it up at Corning
I'd chop it while taverning
all over this land.
I'd chop it for a stranger.
I'd chop despite the scorning.
I'd chop it like Norman Bates -- the shower scene (hey! I found a spleen!)
all over this land. :rolleyes:

Ahem. This is leftover cane, so "murrini" is probably an overly-generous appellation. Also I'm cutting it at a 45 degree angle in an attempt to give a little depth and dimensionality.

[Eben Horton]

The key is to never let them dry out after you cut them on a saw- I have a friend who is really anal about murrine and he goes to great lengths to have the cleanest outcome possible- I dont feel comfortable telling the world who he is or what he does, but Just saying to always keep them wet until you go to clean them is a huge tip.. if you let them dry before cleaning, its 4 times as hard to clean them.

[David Patchen]

I don't think you need to worry about cutting them for dimention. Keeping the glass on the thicker side after you pick them up should help maintain dimentionality. If you blow them thinner, they will likely become thick short stripes.

[Lawrence Ruskin]

I met these guys that were making beads from murrini.

The faces were highly polished so I figured they were using a vibrating flat lap or whatever it's called.

Soooo...they must have done hundreds at a time and cast them in some kind of matrix that they could flip over to do the other side like a glass pancake.

What would that matrix be?

[Brody Shaw]

What would that matrix be?

plaster, possibly

[Allan Gott]

.........wax........

[Doug Sheridan]

I've tried slumping rough cut murrine ever so lightly, worked perty good.

[Ben Solwitz]

I've had pretty good luck doing a full fuse into a clear sheet without any polishing. I just swished the murrine around in a cup of soapy water for a couple of minutes and rinsed them off. The ground edges weren't noticeable on either side after the fuse. It did trap some small bubbles on the underside of the murrine, but they were fused into a sheet of single rolled bullseye so that was pretty much inevitable.

[Kenny Pieper]

I bet an ultrasonic cleaner would help

[Scott Hegan]

I've heard that you can put them in the dishwasher in a colander and it works.... never tried.

[Brian Blanthorn]

Good questions. Based on my own trial and error, I've found murrine cut on a saw won't fire polish nicely. Even if you get it ripping hot, it will still look dirty from all the crap that's on the rough cut surface. (You shouldn't get murrine ripping hot anyway, but that's another issue). What I've found works is a 100 grind on the murrine that's on the outside--this lets them flame polish nicely. If the inside is cut as well, I do an additional polish to 400 using a SiC belt sander and it's perfectly clean. You can cheat by going 100 on both sides and once it's hot you hit the bubble side of the murrine with MAP gas to flame polish it before you pick it up. Works ok if you only have a couple murrine that need it. Taking it to 400 only takes 20 seconds longer in the cold shop, so that's what I do.

I've seen people take the murrine to 100 grit on both sides, then after it's fused and flame polished on one side, they flip the murrine over. I think this can create additional issues that aren't worth the time you might save in the cold shop. You might like it though.


Here is some technology U might consider

Embed a number in candel wax + bit bees wax then saw then U could lap or mayb linish ( clean linish with wire brush )

And or then tumble, sand might B a little abrasive so try some sized waste cullet

If U wanna get in2 some mass making arrange the cullet 2 B smaller / larger then the murani

Then sieve it out cullet needs 2 be say 40 gram or less each

Alternatively or as well as try sawn up bamboo or garden sticks sawn up together these will float off when fin

Brian

[David Patchen]

Thanks for the ideas. Out of an entire pull depending upon how cleanly they chop, I probably only end up grinding down 5-15, so only takes 3-10 min. max.

[Wes Hunting]

I've been using a .025 diamond blade and clean with water for quite awhile. No additional clean up necessary. Didn't we have this discussion before?

[Jody Fine]

acetone can work wonders. but a nail nipper will work better.