Glass is non reactive This is the big one for us. From the beginning of our foray into vaping when we saw what certain flavors did to plastics we decided there wasnt much sense in taking the risk. There are several different possibilities for reactions with different plastics depending on the flavors used and the processes to extract those flavors. Even using flavoring that does not exhibit corrosive behavior or no flavor at all using glass has been the preferred choice. Borosilicate Vs PYREX Vs Fused Quartz There is often quite a lot of confusion with these. First off is the fact that Fused Quartz should have never been sourced for vaping devices. This glass has some special properties that make it ideal for certain applications where there is very high heat like over 2000F or for absolute optical clarity. Fortunately vaping devices need neither of these, unfortunately because it is much more expensive some thought it must mean it is better and designed their devices for it. Fused Quartz is also much harder but this plays against us when a device takes that inevitable tumble because harder also means more brittle or less shock resistant. Borosilicate and PYREX has always been a source of confusing for many, these are one in the same. Borosilicate glass was invented by Dow Corning many decades ago and sold under the name PYREX, quite some years ago they sold the name PYREX to a European company who produces many types of glass products that may be boro or may be soda lime glass so it no longer describes what most know as PYREX. We use the term Borosilicate as it is accurate as to what the product is though it does cause some confusion. Borosilicate glass was developed for its shock resistance which is why it is so popular in dishware. It also has a low COE (coefficient of expansion) which allows it to heat up and cool down without breaking and this is why it is used in widely in cookware. The importance to us is in its strength. Not all borosilicate is equal, there are maybe only a handful of manufacturers who produce high quality borosilicate glass. Ours is produced by Simax and they are regarded as well as it gets in glass tubing. Most borosilicate glass of chinese origin is not considered as a quality product in dimensional consistency, true borosilicate component ratio or annealing which is where stress is relieved from the glass and a big part of where its strength comes from so its impossible to tell what you will get from one lot to the next. Glass manufacture and tolerance needs in design of devices Every size of glass has its own specification with the very best having +/- 0.30mm though most of what we see is very close to the nominal size. Device design of intended to have glass fitted to it should first off leave tolerance of something close to the manufacturer specification for that size of glass tubing. Some culling can be done but if the tolerance is too close the waste ends up making it impractical. Design tolerance ensures and metal part of a device that goes inside of the glass tube or surrounds the outside of the tube ensures that most if not all glass for that particular size will fit the device. Along with the minimum size considerations to make sure the metal parts do not conflict with the glass is the other end where glass might be running large rather than small. Here the design can accommodate some variance by using orings with a thick cross section (CS) to be able to maintain a seal. Most of what we see is devices using 1.5mm or larger CS have far fewer issues. The last note in design is glass thickness. Sure using thin glass gives slightly more volume for liquid it also sacrifices strength in the glass. Considering this and the tighter tolerance in manufacturer the best size for a 22mm device would be 22 x 1.8mm as this is a robust tube and the specification on it is closer to nominal than other sizes in that same diameter. The 22 x 1.5mm wall thickness tubing does work quite well and is popular for many devices but it does have a higher tolerance in its specification and the small difference in thickness to 1.8mm adds quite a lot of strength against impact while trading very little in terms of internal diameter. As diameter increases wall thickness needs to increase to maintain the same level of strength. Tips for measuring There are several considerations for fitting glass to a device. First and foremost is judging if glass is appropriate in the first place. There is no way to make fine threads in glass as many devices use in their tank section. All of our glass is cold worked to retain the manufacturers annealing so we dont do any kind of forming or lampworking. This means if the tank needs to be anything other than a straight tube we dont make it. Next up is considering the limits. If the glass is to go inside of metal or metal to go inside of the glass then these metal parts present limits. As mentioned above glass has a range of size that needs to be considered. Inexpensive calipers and why you should own them Here is a set at Harbor Freight currently only $14.99 that are capable calipers. Note that these have all metal tangs and backbone and they are only 4" but that is plenty for the vaping toolbox. Dont bother with all plastic calipers as they have too much flex in the them for accurate measurements also dont use metal calipers to measure a battery because you can short the battery through the caliper. I always try to encourage folks who are seeking glass for their devices to purchase these or something similar. Owning a set of calipers will let you know just what size tube you have on your device. All of our tubes have their size in the description so you will know your are getting the correct tube for your device and we have many sizes of tubing available for custom lengths. With so many devices out now, similar naming, replicas and just changes by the manufacturer knowing what you have will go a long ways in being able to keep glass on it. I will be updating this post with further details but wanted to get it up in the hopes it might help some in terms of purchasing devices or encouraging device makers on those design choices in making products that best benefit vapers in the long run.