View Full Version : Fusing Spruce Pine murrhines with Reichenbach

Michael Mccain
02-22-2012, 12:10 PM
I never remember how to spell murrihne. I'm trying to fuse up a 24" round plate made up of 1" muurreenee. I make a bar with R-41 in the center, case it, and wrap on some R-54 and R-212. Chop that up into little wafers and fuse them together, but the plates keep cracking like there's an incompatibility-maybe?
The firing cycle peaks at around 1375, and I've stretched my annealing time to 4 hours at 950, 3 hours to 750, then another 3 hours there. but the darn things just won't come out hole.
When I use these colors for blowing they're fine, so why do they check in the kiln?
Is it the size of the thing that's making it crack?

Pete VanderLaan
02-22-2012, 12:40 PM
Differences in viscosity. Read what Dan Schwoerer from Bullseye has had to say on the subject. Not only is it enlightening, he's right. Linear expansion is only part of the puzzle. It's off somewhere in Antiques and Classics in the archives.

David Patchen
02-22-2012, 01:27 PM
Try using gaffer and coming down slower. I wouldn't touch that R stuff for murrine. I anneal blown stuff with lots of color much slower than that so I would think you need to be much more conservative for something that wide. Maybe fusers can help, but I'd try 12 hours to 700 then another 12 to 250. But that won't help if your R color doesn't work.

Zach Jorgenson
02-22-2012, 01:27 PM
a 1" thick plate? I would stretch the annealing out much farther, at least six hours to 800, 2 hours to 700 at the fastest. The fusers recommend including the thickness of the kiln shelf in your calculations, which would lengthen the time significantly.

Of course these glasses may not be all that compatible as Pete said. Blowing thin is a lot more forgiving than fusing.

Jeff Thompson
02-22-2012, 01:47 PM
I've been making psuedo-fused murrini sculpture that is about 3/4 inch thick. I soak at 950 for 20 hrs. Ramp to 700 over 20 hours. Ramp to 200 over 20 hours. I still have some that check. Good luck!

Michael Mccain
02-22-2012, 01:57 PM
Huh. Thickness of the shelf... that would have never occurred to me. And now I dig through the archives...

Pete VanderLaan
02-22-2012, 03:14 PM
In a nutshell, linear expansion is one factor but the final determination for annealing strain is where the glasses are at the time they hit room temperature. If theory says that below the strain point, no further annealing can take place and that all you are doing at that point is to prevent thermal shock, then something else indeed is going on. Linear expansion is proposed as just that: Linear. The expansion and contracting on cooling between different viscosity glasses suggests that something different is going on. Glasses that fit in thinner blown ware are not going to necessarily fit in thick cast or fused ware since the relaxation of strain is taking place differently in the wedded glasses. All that lead in the german glasses masks a lot of issues.

Tom Fuhrman
02-22-2012, 07:39 PM
try using Bullseye for doing this and see if that makes a difference. Many of the fusers do this type of work all the time but they don't use REichnbACH. they almost all use either Bullseye or Spectrum all tested compatible glass but even those have problems at times.

Michael Mccain
02-27-2012, 11:14 AM
One incident I recall was when I was with Libensky in his studio and they were looking at one of his castings that had a large check in it. It was a piece that was a large cube held in the air with a much thinner protrusion. They had followed to the letter the "scientific" annealing and cooling curves but it still cracked. Libensky said double the annealing and cooling cycle. They did and it worked. After that he had them cut that arbitrary doubling of time by a third and found that that also worked. Bottom line was, when science fails you double everything and hope it works.
Henry Halem

I love the archives

Pete VanderLaan
02-27-2012, 11:41 AM
That must be why Mitt is "Doubling down" about his Cadillacs. Everyone reads Glassnotes.

Lawrence Duckworth
02-28-2012, 05:24 AM
I mixed orange and new green about two to one and the stuff turns a metalic when torched a little. There's probably something in Glass Notes on this,.....I'll look tonight.

Btw...Monday night nascar. Don't git much better than that does it. :)

Pete VanderLaan
02-28-2012, 06:24 AM
Btw...Monday night nascar. Don't git much better than that does it. :)
Um well, yes it does... I view the NCAA basketball tournament as a great thing because it means the baseball season is just about to start. I prefer open wheel racing.