Glass & Ceramic Guide

What is milk glass made of?

Vintage milk glass was made white by adding opacifiers to regular glass to give it its signature milky, or opaque, look. Historically, these opacifiers were usually bone ash (from animal bones), tin dioxide, arsenic, or antimony compounds.

Modern milk glass, also called opal glass also uses opacifiers, but they’re much safer. The most common opacifiers used today are titanium dioxide (also used in sunscreen) and tin oxide (considered safe, even by the EWG.)

Is milk glass safe?

Modern milk glass, also called opal glass, is safe.

Vintage milk glass made before 1970 may be safe on a shelf, but not for frequent touching without hand-washing afterward, and definitely not for storing foods in or cooking with, because of the possibility of heavy metal inclusion.

If you have a vintage milk-glass lamp sitting on a bookcase (like I do), these heavy metals won’t jump out at you without friction, acid, or heat, and you can probably keep it there as a decorative piece. But, if you or a family member or pet are licking it, or touching it often without washing your hands, that’s cause for concern.

If you're not sure whether your milk glass is vintage or modern, treat it as decorative only. Modern milk glass from known manufacturers with food-safe labels is fine for everyday use.

Read more about the complexity of lead safety and other heavy metals in my Metal Guide.

What is crystal glass?

Crystal, also known as lead glass, lead crystal, or leaded crystal, was made historically with lead, sodium, and silica, instead of calcium, sodium, and silica (like 90% of glass is made of today.) This was done because lead made the glass sparkle.

Modern crystal glass uses other minerals, like zinc or potassium, instead of lead or calcium to achieve a similar effect.

Is vintage crystal glassware safe for drinking?

No, definitely not on a regular basis, if you’re pregnant, a child, or have stored acidic drinks in it.

Vintage crystal contains lead oxide, which will eventually leach into beverages, especially acidic ones like wine, citrus cocktails, or fruit juice. The amount of leaching increases with contact time and acidity. Storing liquids in a crystal decanter for days or weeks will definitely cause lead leaching. Pregnant women and young children should avoid crystal entirely, even for occasional use—there's no safe level of lead exposure during development.

Using crystal occasionally for a dinner party, like pouring wine and drinking it within an hour or two—creates minimal lead exposure, possibly none. It probably isn’t worth doing, but you can read more about why lead is so common in products still and how to think about exposure in the Lead section of my Metal Guide.

Modern lead-free crystal alternatives exist if you want the aesthetic without the risk. These use barium oxide, zinc oxide, or potassium oxide instead of lead to achieve similar optical properties.

Is it safe to have Depression glass in my home?

Yes, it you’re just displaying it, and possibly even if you’re using it very infrequently, aren’t pregnant, and aren’t storing or drinking acidic beverages out of it.

Depression glass is colored glassware that was very popular in the 1920s through 1940s. It contains various metal oxides for color— the pink, blue, and amber pieces may contain manganese, cobalt, selenium, or other metal compounds. The interesting ones are the yellow and green varieties, which often contain uranium oxide, making them slightly radioactive! Also called uranium glass, or Vaseline glass because of their yellowish color, they glow under blacklight.

While it sounds scary, these glasses are less radioactive than bananas, and are generally considered low-risk for display and occasional use— this isn’t random, but has actually been measured. The maximum dose per year for a person constantly in close proximity to uranium glass, like a driver transporting it, would be about 4millirem. Considering we get around 620 millirem per year, about half of which is just from cosmic rays and the Earth itself, this is very tiny. Here is a graph showing how much radiation you’re exposed to yearly from cosmic rays, other people’s bodies, chest x-rays, and airplane flights.

The bigger concern is that these pieces may also contain lead or other heavy metals that can leach into acidic foods or beverages.

The safest approach: keep Depression glass and other colored vintage glassware for display or very occasional use with non-acidic, non-alcoholic beverages. Don't store food in it, microwave it, or put hot liquids in it. The combination of heat, acid, and time increases the likelihood that metal compounds will migrate from the glass into your food or drink.

If you use vintage colored glass regularly, consider testing it for lead with laboratory analysis (consumer test kits are unreliable for glass). Or simply switch to modern colored glassware, which uses safer pigments.

When did manufacturers stop using lead in glass?

This depends on the type of glass.

Lead was never used in standard soda-lime glass for everyday dishes and jars, so it’s always been lead-free.

Lead was used in crystal glass, vintage colored or decorative glass as a colorant or stabilizer until the mid-20th century. Vintage pieces from before the 1960s may contain lead, cadmium, or even uranium.

Why is glass or ceramic with positive XRF testing considered “use caution,” not “harmful” on your scale above?

Leach testing is a much more accurate way to test whether or not the presence of a heavy metal is able to escape into your food. Read about the difference between the two and what the results mean in the lead testing section of my Metal Guide.