Thread: cullet shortage
View Single Post
Old 03-21-2018, 08:45 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 22,268
Pete VanderLaan is on a distinguished road
Lets clarify a bit here.

Durk is talking about batched glasses in a gas unit I believe. Nephelin is a type of feldspar which has a basic structure of soda/potash/ alumino silicates. Durk implies that it forms but is not introduced into a melt. My interpretation of that is that in the flue, there is a phenomenon of devit flakes occurring when the temps are just right, somewhat on the colder side.

Calcium aluminate is used as the cement in castables which hasten the setting of the castable but reduce it's resistance to attack at the same time.

Jordan, I believe is not talking about gas units at all but is referring to cullet melting. The glass he refers to was the system 96 made by spectrum in conjunction with now departed Uroboros which indeed was a low temperature mel cullet that chowed down ( a technical term) on silicates, aluminates and fireclays in a variety of furnaces but was really worst in electric units with no flues. The liner photo he shows is I believe, a wet dog cast portion that dissolved using the system 96. Jordan appears to say he is not seeing the same kind of dissolution with the Cristalica but needs more time to watch it.

Both of these glasses currently are under scrutiny because of their Boron content. Boron with barium around 3% would in my mind add to the issue. I am getting feedback from some kiln makers that the Cristalica is having detrimental effects on their products in a short time. That is using alumina crucibles from either High Temp or Engineered Ceramics. The crucibles do not appear to be affected and I would have expected that they would be.
It seems to me that the jury remains out on the affect the German cullet will have on the American furnaces. Simply put, European furnaces in general use higher quality refractories.
The GLASMA claims Durk makes in the Gas units is not something I can really compare anything to. First, I don't know what GLASMA Batch it is and secondly, it certainly sounds like a very different furnace structure as well as being gas fired, not electric. It remains to be seen whether Cristalica gets the boron out of the goop. I certainly advocated for that when Tom Littleton and I first brought the stuff into the country two years back but as I have noted, they declined changing anything. I am no longer affiliated with that arrangement in any way. I do sell pots.

I hope that sums up what I can see would be fairly confusing. Is that the case, and am I accurate?
Where are we going and why am I in this basket?
Reply With Quote