[Steppes] Roman Standards

[uilliacc]

the  gravitational effects on glass can be seen in windows  less than  
100 y.old,  it is startling at first...

the cloudy outside also suggest abrasion as the possible method of shaping

as for annealing or slow cooling,  thicker glass which has more volume 
to surface area retains its internal heat longer and is easier to 
produce...  thinner glass gives up it's heat much quicker leading to 
more brittleness

were the molds stone, pumice or cast refractory? the Romans were quite 
advanced in their plaster/concrete knowledge -cast refractory could be 
very similar to either...

AlKudsi at aol.com wrote:
> I yield to your greater knowledge of glass, although the pictures I 
> saw didn't really show whether they were hollow or solid. Hard to tell 
> from a photo when the outside is cloudy. A lot of the early Roman 
> glass I actually saw in Rome was crazed and somewhat brittle. At 
> Murano, the glassblower we talked to said that the annealing technique 
> took centuries to perfect.  Not being a glassworkermyself, except for 
> glass enamel beads, I'm just going on the research I've read, and 
> pieces I've seen. The molds we saw in Rome were made of stone and 
> already in the shape of the object (a tumbler, in the case of the one 
> I saw). Pouring glass into the mold, you could make both solids and 
> walled objects, though. To me, that indicates a "mass production" 
> technique, and gave natural annealing as it took much longer for the 
> glass to cool inside of rock molds.
>  
> It is interesting, and will be fascinating to see what further 
> research determines. One thing that always fascinated me is that glass 
> never actually "solidifies". It remains a stablized liquid and over 
> centuries, continues to move. You can determine the age of stained 
> glass windows by comparing the width of the glass at the top of a 
> panel to the width of glass at the bottom. That is just so COOL!
>  
> In minerals and gemstones, grinding is more popular with materials 
> with little to no clevage points and a more disorganized structure, 
> faceting more popular with strong clevage points and a more 
> crystalline structure. One of the reasons emeralds (or beryls of all 
> kinds) are faceted into emerald cuts most frequently is that they have 
> strong natural clevage points. It is actually much harder to cut 
> rounds or ovals than step cuts.
>  
> Saqra