Sand Quality

[Fire1981]

It’s my understanding that the sand each factory used to make marbles played a part in the quality of the glass. I’m under the impression that Pelt’s sand produced the bubbles because of the difference between the sand used in Ohio and West Virginia. Pelts also seem to have the most kiln debris  in their clear base based marbles then the other factories. Was it the quality of the kilns and sand that made certain traits more trace able as an ID ? Or ? 

[Alan]

That assumes that factories sourced their sand from single sources which were in themselves consistent.  I wouldn't assume that.

In glassmaking, bubbles are usually a phase in cullet/substrate melting.  Glass which is not fully up to temperature can often contain bubbles.  I saw that in a glass pot on Wednesday.

[wvrons]

The bubbles in the glass can be caused by many things, making glass from raw materials or cullet.  Some problems that can cause the bubbles, temperature, air to gas raitio, amount of exhaust, time, to much or to less of a ingredient, etc.   Mid Atlantic of WV, their main production was clear crystal glass items. The glass had to be 100% clear no bubbles at all. The furnace where they made the batch held twenty tons of glass. I was there one day and they were having trouble with what they called seedy glass, bubbles. The owners, a engineer and the old timers had worked with it for about twenty four hours and no change. I was back there the next evening and they(6 workers)were ladling, emptying out onto the floor the 20 tons of glass. The next day shift would make a new batch. I was back two days later and the same thing, bubbles again. That afternoon a maintenance man was greasing bearings on roof fans. He noticed one out of four exhaust fans for the glass tank had the belts broke. He replaced the belts and the bubbles in the twenty ton furnace cleared up. Of course the larger things are the more each problem is magnified. Clean sand and particle size is important but sand causing bubbles may be down the long list of causes. The bubbles are usually from a equipment problem or human error. Heating to fast or to slow can cause problems. The debris can be from not so clean sand, or from the actual furnace bricks. Or in the cullet if cullet is used. There are different quality in furnace bricks. Some last longer and take higher heat than others. Of course the higher quality cost more.  When the bricks begin crumbling off, it may be time to build a new furnace. But if orders were behind, they probably kept running it. 

[Chuck G]

Ron, another and more quality information for those who are interested in glass.  You (always) bring the BEST to the dinner table to dine on. Chuck G---

[Fire1981]

Thanks Ron ! Your explanation definitely answered all my questions.