Drilling old glass?
 

I have some old tanks, probably over 20 years old that I would like to drill. I have been told by an aquarium builder that this glass would be too brittle to drill because of its age it is likely to chip or crack. Anyone have experience with this? I had never heard of glass becoming more brittle with age.

Plexy does not glass. Ask someone else to drill it for you.

Ive seen glass leaning up against a shed sag due to direct sunlight , It was in direct sunlight for over 15 Aussi summers.
I guess that glass could become brittle over time but I think only if the conditions were very harsh ie stored in the sun/snow over this period.
maybee some one else with more direct an experiance will chime in.

I have drilled a bunch of old glass without issues

Glass is always in motion although very slow ove time glass from the top of a window runs down to the bottom, giving a preson the idear that it is brittle but it is only thiner at the top there for it breaks easaly. tempored glass my be brittle but you don't want to try and drill tempered glass any ways. You will have to check and see if it is tempered, I know a glaser that willnot cut old glass just because it is alot harder to cut. When you cut older glass it can break easer and break lines may run on you.

Bill

This is a common misunderstanding. Often people state that glass is not solid but a super cooled liquid. Silica's melting point is around 1200C and temperatures between 10-even as high as 40C are so far away that even if Glass was not truly crystallized the time it would take for glass to flow to a noticeable difference is beyond a human time frame. The better explanation for thicker glass at the bottom of old buildings or ancient churches is the actual glass production process and glaziers preferences of setting glass with the heavier side at the bottom.

I"ve seen sagging glass however this is a good deflection of my experiances
http://math.ucr.edu/home/baez/physic...ass/glass.html
alt

I can only go by what a glass glazer has told me. Nice artical though. sorry guys I have been missled have to go bust a knee or two...lol

Bill