Special Projects: Custom Glass Beakers
The custom jacketed beaker pictured on the right (below) is our latest iteration of this venerable piece of lab glass. We have produced quite a few of these large beakers, often with jackets for temperature control. People want to see....
The opening across the inside is just under 10" and measures a very shallow 50mm depth. That's a 4mm teflon stopcock drain porting out the bottom of the beaker.
"Custom" can present challenges. The requirement for such a shallow depth on this jacketed vessel meant that we would not be able to produce it our normal way.
Pictured on the left (above) is this beaker during manufacturing. It is mounted horizontally in a glassblowing lathe and the inside portion, the beaker itself, is about to receive its jacket, which is mounted on the left. Scientific glass is constructed in this fashion, inside-out. The shallow aspect of this construction made our standard procedure of "shimming" the internal component unrealistic, so we thought we'd try using a vacuum chuck to hold the inside of the vessel while making the large ring seal at the top. The chuck consists of a graphite head mounted on a stainless shaft that holds the internal component stable using vacuum against the flat bottom of the beaker. You see pictured the flared beaker held by the vacuum. The large flare will effect the Dewar seal, and the bottom port sticking out is in preparation for sealing the stopcock through the jacket. The array of burners at the bottom will locally heat the seal.
The success of a new technique is not a given. The challenges are several; will the strength of the vacuum be enough to support the inside while melting and fusing the glass ringseal? Will anything melt or burn up?! Can we keep everything hot enough during assembly to prevent the thermal stresses from shattering the works? You can imagine that any problem during hot glass fusion is a BIG problem and is mostly catastrophic.
Not this time! Challenges are constant for glassblowers, as are the thrills.......