Q: My 55-year-old Waterford crystal vase has developed a haze on the bottom third. I have tried (not all at once) bleach, baking soda and vinegar treatments. Nothing has worked. Is there any remedy? The vase was a wedding gift, and I would hate to trash it.

Arlington, Va.

A: The haze could be from mineral deposits that formed when water in the vase evaporated, or it might be etching that formed because of a chemical interaction with whatever was in the water. If you are dealing only with mineral deposits — and a customer service representative for Waterford said that’s common on vases as old as yours — you should be able to get the glass clear again. But if the glass is etched, there is no simple solution.

Mineral deposits are typically alkaline. In a vase, they result from minerals in tap water and ingredients in the “flower food” packets often added to keep cut flowers fresh, said the Waterford customer service representative, who could give only her first name, Deanna. The deposits, which are left behind when the water evaporates, build up so gradually that it may be many years before you notice them.

To remove these deposits, the opposite chemistry — an acid — usually works best. But too strong an acid, especially if it’s left soaking too long, could make the cloudiness worse. Many Waterford vases, probably including yours, are made from lead crystal, in which lead is added to the glass during manufacturing to make it sparkle. Acids leach lead from the glass, which is why Waterford warns customers not to use its lead crystal containers to store food or beverages for long. For a vase, the side effect would be an etched surface where the lead leached out.

However, by being careful, you should be able to remove most or all of the cloudiness with white vinegar. Waterford recommends filling the vase about halfway — at least just beyond where the cloudiness ends — with warm water, a small amount of hand dishwashing detergent, two tablespoons of white vinegar and ¼ cup of uncooked rice. Gently swirl the mixture for a few minutes to remove the residue. The rice should help knock the deposits loose, Deanna said.

Pour out the mixture, rinse well with warm water and dry immediately. Deanna said her most important tip is to avoid letting the vase air-dry; that’s almost guaranteed to leave water spots on the glass.

If the vinegar solution doesn’t clear up the glass, Waterford suggests repeating the procedure using two tablespoons of ammonia, which is alkaline, instead of the vinegar.

For especially stubborn deposits, Waterford recommends a third option: denture cleaning tablets. These typically include citric acid (the chemical equivalent of lemon juice) and effervescent ingredients that help stubborn deposits bubble up from the surface. Just fill the vase with warm water, drop in a tablet and let the solution sit for 24 hours. Then empty, rinse and dry the vase with a soft, lint-free cloth. You can repeat this process up to three times if necessary, Deanna said.

If none of this works, the glass is probably etched, in which case the only possible solution would be to take your vase to a company that specializes in repair and restoration of cut crystal.

Chatree Suvanasai, who runs Chatree’s Conservation and Antique Restoration in Alexandria, Va. (chatrees.com), said he can polish out etching on glass, but doing this on the interior of a cut-crystal vase would be very difficult and time-consuming — and therefore expensive, probably costing several hundred dollars. And even then, he cautioned, he would not be able to make the vase look like new.

There are two challenges with crystal vases, Suvanasai said. Like the glass in soda bottles, the glass in your vase consists mostly of white silica sand. But crystal glass has different added ingredients, and it is heated to a much higher temperature. These changes make the glass very hard. Suvanasai said that, to polish out scratches from crystal, he would need to use the same techniques and equipment he would use to polish ruby or sapphire. That’s not a problem when he has easy access to the surface that’s etched, because he can hold those pieces up to his grinding and buffing wheels. But polishing the interior of a vase is difficult because of the tight access. And getting the tools into the sharp angle where the sides of a vase meet the base is virtually impossible. So although he might be able to polish out most of your vase, he would not be able to get rid of any etching near the bottom.

Suvanasai said that, although he has taken on the job of polishing vase interiors a few times, he discourages people from asking him to do it; he doesn’t want to have disappointed customers. He is happy to polish out chips in rims, though, because there is easy access to that area.

If you do get your vase clear again, follow the cleaning regimen that Waterford recommends. Wash it alone in warm water with a little hand dishwashing soap, and dry immediately with a lint-free cloth. Avoid setting the vase upside down, because the rim is the most delicate part. Never clean vintage cut crystal in a dishwasher, because dishwasher detergents often are highly alkaline and can leave the glass coated in mineral deposits.