Can colorants in glass leech?

[Big Jay]

Can the metals present in glass leech into water? Or do the become bound to the glass. I'm talking about on the most minute level. In other words if you made a non encased colored goblet and kept it filled with water for 2 years straight would testing the water show any trace of metal even on the most minute levels like 1 part per million?

[Glass Pyro]

That is a good question, I think they(metals) would definitely cause the ppm of the water or substance to go up over an extended period.

From what I understand glass is always moving, therefore certain molecules may become more available for absorption by the water.

??????

[Big Jay]

I know they say lead in leaded glass can leech so I guess that really answers the question.

[Mac Maestro]

I just dropped a silvery exotic marble in my fish tank. I'll letcha know if the fish kicks the bucket.

[somewhere]

First let me say glass is a solid not a slow moving liquid. That is a urban myth that should be put to rest.

Next so much info to wade thru but here are some facts.

The container industry has been pretty much self regulating and does not allow any actual color or decoration any closer than a half inch from the lip of a drinking vessel. The rule as I know it goes, no lead within 1/2" of the lip and no lead on the inside exposed to the contents. The container industry has had to sign agreements that says there work is in line with these rules.

Some notes from a ICF meeting in 2002.
Reminder to all manufacturers of glassware containing lead of the crystal warning requirement in California.
All accounts need to be send a full 'master memo' that describes the warning program, also for internet sales selling into CA
There are even "bounty hunters" at large like Bill Verick sued dozens of crystal retailers, even Amazon.com

All articles need signs:
Prop 65
WARNING
Leaded Crystal
Consuming foods or beverages that have been kept or served in the following brands of leaded crystal exposes you to lead, a chemical known to the state of california to cause birth defects or other reproductive harm:

They go on about painted glassware, hand to mouth issues,

http://www.calprop65.com/

Here's the one I found to be most interesting and is from Chicago Artists Resource .org

This includes cadmium and more.

Glassware Decoration Limits
In the July Issue of Orton Firing Line, there was a reprint of Peter Cassebeer's article on the decorating industries voluntary standard concerning enameling, with lead and cadmium enamels, on glassware. Cassebeer states that decoration area limits sometimes don't satisfy the standards.

The voluntary standard for the decorating industry for lip and rim limits is based on the ASTM test C-927-80, which provides a test method for lead and cadmium extracted from the lip and rim area of glass tumblers externally decorated with ceramic glass enamels. Within the test procedure, a 2 centimeter distance from the tumbler rim is established as the limit for the lip contact area. The decorating industry has chosen to not decorate above this 2 centimeter mark with lead and cadmium based glass enamels to minimize the potential for consumer exposure to heavy metals.

However, Cassebeer noted that some decorators are using a 3/4 inch decorating limit for tumblers, meaning that they decorate the exterior surface of a tumbler up to, but not above, 3/4 of an inch from the tip rim of a tumbler. Consequently, there is almost one millimeter difference between these measurement.

2 centimeters = 20 millimeters = 0.787 inches

3/4 inches = 0.750 inches = 19.05 millimeters

This tiny discrepancy could make the difference between complying with the decorating industry's voluntary lip and rim standard or not, or selling glassware that meets FDA criteria for a safe product and one which fails. The difference translates to a 5% surface area discrepancy, and also potentially exposes the tumbler to 5% more decorated surface area to be leached from in the ASTM C-927-80 test. If the tumbler was close to the FDA limits for lead and cadmium in the lip and rim area when using 2 centimeters, this extra 5% exposure may be enough to push it over the limits. Glassware decorators are encouraged to use the 3/4 inch measurement as their decorating limit.

This scenario shows how accurate and careful artists and craftspeople must be with their measurements for health, safety, legal, and artistic reasons.


Art Hazard News, Volume 18, No. 4, 1995

[menty666]

I'd say after 2 years, probably. But if you keep in mind the amount of time that a beverage is going to be in a glass in normal use, I'd say it's pretty safe.

Be a good question for Henry, Paul, or Momka though to see if they know. I'd say call the reference desk that the CMOG library but given they have thousands of years of info at their disposal you might not get an answer pertaining to the newest glasses.

[menty666]

First let me say glass is a solid not a slow moving liquid. That is a urban myth that should be put to rest.

Wait a minute...how do you explain the windows they've found that have grown thicker at the bottom than the top over time? While some thickness aberrations are of course due to less modern manufacturing, it all can't be attributed to that.

Also, glass is widely regarded as an amorphous solid, not a liquid. But certainly not a "stable" solid like wood or metal.

As for the self regs, they mostly seem to pertain to leaded glasses, most of the boro glasses aren't, right? I'm sure some colorants are more dangerous than others, for example you don't see red or yellow wine bottles, but the blue/green/amber/clear ones can sit on shelves for ages without making the contents unsafe from the contents of the glass.


edit....never mind the first two paragraphs. I found this and it's rational enough I'll take it as fact.

[somewhere]

Geeez Menty I was saving that article and others for Glass Pyro. You just take all the fun out of it.


I'm still reading more, some of the articles cover cadmium and others in enamels. I'll post more as I find it. This is a good question and should have some good answers.

[brettodie]

they didnt "grow" thicker thats how. some older windows were made by hand or put on a sheet roller. when they installed the windows it makes sense to put the thick part down. as far as colorents go i talked to a materials science guy from the netheralands several yrs ago about it he was doing research on leeching from non-leaded soft glass glasses ect. if i remember correctly he said the chance of leeching was very small,and had to do with leaving acidic substances in the vessal for prolonged periods of time. peace brett

[Glass Pyro]

Why do automobile windows also start to sag and ripple overtime? I have 20 examples in the back of the machine shop, from an old Cadillac to a Bel-Air.

As a restoration guy, I know I have been replacing rippled windows in cars for years, especially the large 2 door car windows....like an old Malibu or Monte or something.

[Glass Pyro]

I have another question too.

I went to a fort in NY one time and some of the panes of glass had big blobs in them...kinda like a punty mark x100. Do yo know what those were?

As a kid I think they told me they were built in magnifiers, but I dunno bout that.

[Conchis]

Are you talking about that stuff that has a piece of plastic sandwiched between two pieces of glass? I don't think it's the glass that's rippling. I've heard the same thing that brett was talking about on the glass flowing. The variations in thicknesses in the old buildings was caused because old glass was spun out so that they ended up with a huge flat disk that was thicker in the middle than the edges. The conclusion that they reached is that the glass, even though it had been there for hudreds of years, was the same as when it was installed.
Wonder if that "punty mark" is where the disk was attached as they spun it out flat?

[Glass Pyro]

I will have to look at the auto glass better next time I am around the Machine shop, but all I Know is I can feel and see what seems to be ripples in the glass, restoration customers see it also, some like the original glass left in some don't.


As far as the fort windows go, I dunno I have to ask my brother, he remembers stuff better than me, maybe I can find a pic of it or maybe he knows what they really were, they did look like lenses though...sort of.

[brettodie]

more then likely they were the punty marks from spinning out the windows. probably not going to put your highest quality windows in a fort, with explosions ect going off at some point. as far as auto glass goes it has plastic in it that probably whats causing the variations over time. a sheet roller will leave variations in the glass also. i think most car glass is float glass but im not sure. peace brett

[Big Jay]

Contempary Lampworking talks about the stained glass sagging window myth. And says its just that a myth.

[Big Jay]

I'd say after 2 years, probably. But if you keep in mind the amount of time that a beverage is going to be in a glass in normal use, I'd say it's pretty safe.

.

because its not really for a drinking utensil its all part of a project I am to trying work on for someone. After I wrote the question I remember reading about crystal decanters saying they are safe to use if you pour the liquid into it and use it for a night. But for general storage the liquid should be returned to its glass container. But it was too late for me to remove the question.

[Big Jay]

thx for the info somewhere. Much appreciated as always!

[newmexicomagma]

if it were true the lead would have dripped out before the glass even had a chance to move. also all the ancient glass vessals they have found would be in puddles by now if glass moved. i think its pretty obvious its a myth.

[Glass Pyro]

True. I have some pretty old bottles in my "old bottle" collection and they look fine. We also have some antique Italian Glass in the Family that shows no signs of "moving"

[Icarus]

As I always understood it, the movement of glass isn't something that would happen over hundred of years, or even thousands, but would be more realistically measured in tens of thousands of years. So with that in mind, before it was even visually noticeable, the human race would probably be extinct and squids would be earths dominant species... of course I may be wrong.