Glass reacting with water

What type of glass? UV light will have more of an effect than water. Dirt washed out of the air will react to some degree. Cabonic acid and sulphuric acid will also add to its woes. Many things will eventualy lead to the demise of glass. Some grades of glass are less stable than others.

The glass is soda lime silica glass and is more sensitive to dark color glass

Glass will shed particles in water which can easily be measured as silica but we are talking about the low ppb range which the human eye can not detect. I would suspect that there is a source of petroleum contamination that is causing your rainbow effect.

Also how we can clean the surface again .

What is the surface material that needs to be cleaned?

The surface material is not identified. The rainbow effect is disturbing.

glass slowly leaches ions into the water. This leave a very thin layer that has voids which can lead to these rainbows. It take a long time for this to happen. A little acid in the air might accelerate it.

Hi aurizon. I aleays presumed that over time glass will start to crystallise. A glass by nature is an amourphous substance which is highly unstable, but even volcanic glass like obsidian will crystallise over time. The silica in obsidian crystalises to a mineral called Cristobalite, which is cubic in form. There are other constituents than silica in obsidian, potassium, sodium, aluminium etc but these tend to be oxidedised and dispersed over time leaving pure silica. It could be that the rainbow colours are a result of the oxide films on the surface, this go's for most manufactured glass as well. I would apreciate your thoughts on this one. Scapolie.

Guest,

I believe that you are mistaken... Under typical conditions (on this planet at least) the "silica in Obsidian" does NOT crystallize into Crystobalite, and not into the high temperature cubic form of that mineral. (High temp. Crysatobalite forms at temperatures exceeding approx. 1400 degrees C). You may find white crystals of Crystobalite in or on "snowflake" obsidian, but my understanding is that the majority of these crystals typically formed before the mass of molten silica was rapidly cooled into the mineraloid Obsidian in the first place. Crystobalite is often found in the metastable, tetragonal form, that is more compatible with earth surface or near surface temperatures and pressures. (Consider the liquidus temperature of silica glass).

Glass can crystalize, but it is rare ans the process is very slow.

The leaching occurs in soil as bacteria grab ions from the matrix.

You must also have the lowest grade of cheap glass for this to be noticeable.

Modern glass for beer and soda is fairly high quality to toleratre the temp changes of washing cycles

I have lived in rural area's where the keeping of "junk" is common place. Old tires, trucks, wads of bailing wire, empty feed bags, jars of screws and nails and many other not readily needed items. Everything is kept because you never know when you may need it for something this also includes windows. I know that by this point people are saying "Richard what does that have to do with the thread?", the point that I am working towards is over the years I have never seen this "rainbow" effect from the glass dissolving into water. My fathers junk collection has in the neighborhood of 2,000 sf of glass much of which has been exposed to rain and snow for well over 20 years and still I have never seen a "rainbow" effect as being discussed here.

Not saying it not occurring but now my curiosity is peaked and I would like more information myself. How would you define "a long time"? Are there any specific conditions to be met or would taking any piece of glass and placing it in a bowl of water suffice? And to clarify, where is the rainbow effect seen, on the glass or on the surface of the water? I was thinking the Rainbow effect was seen on the water.

To narrow the field, try cleaning the glass sample with a de-greaser (since the "rainbow effect sounds like petroleum based contaminate). If the rainbow is still there, you're almost certainly dealing with crystallization of the surface from UV exposure.

Try leaving a piece outdoors, but under a shield to protect it from the weather (clear glass, so UV still hits it), then another piece under UV protective glass. This would be a neat little experiment!

I have seen this effect numerous times on old bottles that have been dug up from landfills. Everything and all was once dumped in these areas, but I'm sure none were exposed to UV rays. Since glass is a supercooled liquid it may perhaps be absorbing contaminants. On badly "rainbowed" glass I have not sucessfully cleaned any. These are however antiques not new glass. The final results may or may not be similar but your efforts may be in vain.

Glass coatings to reduce UV will react with the environment over time. This may be causing this effect. Most of these coatings are sealed on the inside of a insulated glass unit. Care even has to be taken in handling it. Oils and acids from your hands will react with the coating slowly destroying it.

Soak in in the full strength clorox for 30 minutes.

remove and wash with water.

It should be cleaned by then

KA

USA

Glass that is in tension on the skin will exhibit "static fatigue" and go to zero strength in the presense of water over time. Micro cracks result and the bond energy facilitates the ion transfer and "decay" of the glass.

Glass that has a compression ("temper") on the skin will not exhibit the loss in strength or the leaching or decay at the temper is increased. The molecular bonds in tension are at a high enough energy state to react with water, but in a compressional state the reaction stops.

The mechanism of glass failure is the ion transfer creating a molecular crack, which then follows typical crack stress concentration factors (lots of research papers on the suject). The crack grows molecule by molecule until it fails.