How do I remove opal coloring from old bottles?

[Adena_man]

I have quite a few old bottles that have "opal coloring" on the outside. I'm not sure if that is the correct term. It looks sort of like a rainbow effect on the bottle. Are there any ways to remove this?

[kc10bull]

Not sure you would want to try that as it will reduce it's value!

[Harry Pristis]

I have quite a few old bottles that have "opal coloring" on the outside. I'm not sure if that is the correct term. It looks sort of like a rainbow effect on the bottle. Are there any ways to remove this?

The iridescence and scaling of the glass is actually the product of the decomposition of the glass. It is typically the result of submersion in acidic ground-water for a long period.

For most bottle collectors, this is an undesireable effect as it diminishes the value of a bottle. To deal with it, you can mask the problem area with a bit of mineral oil, or you can tumble-polish the bottle. There is no adequate treatment that is not some variation of one of these approaches.

[swizzle]

It cost money to tumble a bottle so consider the bottle in question first. You could send it away to be tumbled and pay a pro or make your own set up for a couple hundred dollars and buy the cut copper and polishing compounds, ect... If you have a $5 bottle then chances are it should just be left alone. If it won't come off with a good soak in The Works toilet bowl cleaner or some CLR or even a Muriatic Acid soak for 2 or 3 days then its etched into the glass and only tumbling will take it out. The mineral oil is a temporary fix that some people use but it will need to be reapplied occasionally and if you have to much on it might stain your shelf. If you have a $100 bottle that could be a $250 bottle with tumbling then it would be worth it to have it tumbled. There are very few people who want to see the "Patina" on these old bottles. They want to see the glass the way it was meant to be seen. With tumbling a thin layer of the bottle is basically sanded or polished off. To much polishing or too fast could bust an otherwise good bottle. Good Luck. Swiz

[Newt]

With one of these. It does the inside and out using different cutting and polishing compounds.
Newt