Vintage glass in a thrift aisle is five questions people ask as if they were one. Carnival is an iridescent surface on pressed glass. Uranium glass, including the yellow-green collectors call vaseline, is a chemistry that glows under ultraviolet. Depression glass is a period of inexpensive colored tableware. Milk glass is opaque white. Lead crystal is a heavy cut glass that may or may not contain lead, and the sparkle does not tell you which. A piece can sit in more than one of those. Green Depression glass often glows. A carnival bowl does not become uranium glass because it is shiny. Start by naming the question you are actually asking, then run the check that answers that question.
The object pages are the carnival bowl, the uranium glass dish, the Depression glass plate, the milk glass bowl, and Waterford stemware. Corelle is laminated glass, not any of those five, and it gets its own paragraph so a daisy plate does not get filed as Depression glass. Jadeite is opaque pale green Fire-King, a different white-and-green problem from milk glass. None of these pages prints a price.
Iridescence is a surface
Carnival glass looks oily. Orange, gold, pink, and blue shift across a pressed pattern when you tilt it. That skin is the iridescence, fired onto the glass. It is not paint you can soak off, and it is not a UV glow. Under a black light a carnival bowl may do nothing, or a particular piece may also fluoresce. Those are two results. Write down both, and do not collapse them into one word.
The surface wears off the raised parts of the pattern first. A bowl that is bright only in the grooves and pale on the grapes has weak iridescence. That is condition. Collectors have a vocabulary for it. You can say worn or bright without the vocabulary, as long as the photo shows the high points. Marigold, the common orange-gold, is a color of that surface, not a maker. Purple, green, blue, and white exist. This note will not rank them. The carnival guide is the bowl, the ruffled rim, and the marks some makers actually used.
New glass is made with a similar shine. A paper sticker, a very light blank, and a surface with no wear are reasons to avoid an antique price. Iridescent stretch glass is a cousin with a smooth surface and no heavy pressed pattern. It is a different search. If you cannot see a pressed design, do not call it a carnival bowl to make the title longer.
A black light, and what it is not
Uranium in glass fluoresces. The practical lamp is a long-wave black light, the ordinary collector light, not a laboratory instrument and not a tanning bulb you stare into. In a dim corner, uranium glass typically glows a strong green. Yellow-green transparent glass, the vaseline color, is the usual thrift hit. Green glass can glow too. Opaque yellow custard glass can glow. Color alone is not the test. Plenty of yellow glass never saw uranium, and it sits there looking expensive until you turn the light on and nothing happens.
Say the lamp and the result in plain words. “Long-wave light, strong green glow” is a sentence you can stand behind. “Confirmed uranium” is a laboratory tone you have not earned. Manganese was used in glass too, and it can fluoresce, more often under a short-wave lamp, sometimes faintly. Short-wave is a harsher lamp. You do not need one to sort a thrift shelf, and you should not shine it into your eyes. If the glow is weak and you only have a long-wave light, say it glowed weakly under that light. Do not pick the more exciting chemistry.
A glow is not a maker, not a year, and not a price. Some Depression-era green plates glow and are still Depression glass, pattern and all. Some Fire-King jadeite glows and is still the jadeite bowl, identified by the mark and the rim. The uranium dish guide is the transparent piece this test is aimed at. Pottery with a uranium glaze, including some old red Fiesta, is a glaze on a ceramic body. It is not this glass. The kitchen note already separates that pitcher from a plate.
Mold seams, pontils, and chips
Pressed glass was made in a mold. Carnival bowls and Depression plates have mold seams. A seam is a raised or faint line where the mold parts met. It often runs through the pattern and down a handle. It is not a crack. A crack is sharp, it catches a fingernail, and it usually does not follow the mold’s plan. Run a finger over the line before you call it damage. The Depression plate is full of real chips, and a smooth seam is how those chips get over-called.
Blown glass is a different object. A pontil is a scar on the bottom where the piece was held. Cut crystal stemware is worked after the blank exists, and the thing you can read is often an etch on the foot, not a seam you promote into a signature. Waterford is that etch, plus the cut, plus the chip on the rim. A mold seam on a thick pressed tumbler does not make it crystal. A deep cut on an unmarked goblet does not make it Waterford.
Ruffled carnival rims and thin Depression edges chip because they stick out. Feel the rim. Photograph the nick with the light behind it. A chip is condition. On a drinking rim it is also a mouth. Say so.
The ring is not a test
Flicking a bowl and listening for a ring is folklore. Intact thin glass rings. Cracked glass thuds. Leaded crystal can ring. So can glass with no lead in it. A ring does not identify Waterford, it does not measure lead, and it does not date a plate. The Waterford guide says this in one line because people keep doing it at booths. Use the sound only as a crude crack check: a new thud in a bowl that used to ring is a reason to look harder for a crack you missed. Then look. Do not buy the sound.
Milk glass and the other whites
Milk glass stays white when you hold it to the light. It is opacified glass, pressed in huge numbers, often with no maker’s mark. Hobnail dots and a grape are patterns more than one factory used. The milk glass bowl is that problem. It is not jadeite, which is pale green, and it is not opal Pyrex, which has a Pyrex mark and often a printed pattern. A white bowl with a blue daisy and a Corelle backstamp is Corelle, Vitrelle, a laminated glass from a later decade. Read the bottom before you pick a material.
A UV glow on a white bowl is a curiosity, not a maker. Some related opaque glasses glow. The milk-glass page already tells you not to sell a glow you did not test, and not to treat a glow as a signature. If you tested it, say the lamp. If you did not, leave it out.
Lead, without a number
Lead crystal is glass that contains lead oxide. The lead is why some of it is heavy and why it throws colored light. Later crystal, including lines from houses that used to use lead, was made without it. The word crystal on a sticker does not tell you which. Marquis and other second lines are a different product from the etched stem next to them, which the stemware guide covers. Unmarked cut glass is unmarked cut glass.
This page will not print a percent of lead, a legal threshold, or a “safe use” hour. Those figures live in regulations and in lab reports, and they go stale or get misquoted the moment an article copies them. If you need to know about a particular goblet, use a dishware lead test kit the way the kit is written, or ask a laboratory, and read the maker’s current material note if the maker still publishes one. A swab is a screen. It is not a certificate. Do not decide that a bright ring cleared the glass, and do not decide that every heavy goblet is dangerous. Heavy is weight. Lead is a test.
Dullness from a dishwasher is condition on crystal and on a lot of other glass. It does not reverse. Say the glass is cloudy if it is cloudy. Do not run a piece through a washer to make the photo brighter.
Uranium, without a dose
Uranium glass is radioactive. That sentence is the whole honest start. It is not a reason to invent a millirem figure, a safe number of hours on a shelf, or a story about a booth that “tested fine.” Public pages from national radiation authorities describe uranium glass in their own words. Read those. A collector’s forum is not one of them. This article will not pretend to quote them.
The practical hazards that do not need a number: do not grind, sand, drill, or otherwise make dust from the glass and breathe it. Do not store food against a broken, sugary, or flaking surface and call that a test. A UV lamp tells you about a glow. A Geiger counter, if you own one and know how to use it, tells you a count at a distance you choose. Neither number is a permission slip this page can sign. Intact pieces are what those public notes are about. Dust and a powder you made yourself are a different problem. If you want a number, get it from the authority’s page or from an instrument you can describe, not from a headline.
Reproductions of yellow-green glass exist, some with uranium and some with a colorant that does not glow. The lamp sorts them. The dish guide is the chips, the pattern, and the overlap with Depression glass. Sell the glow only if you saw it, and name the lamp in the listing so the buyer knows what you did.
What a photo can settle
A photo can show a pressed pattern, a mold seam, a chip on a rim you lit from behind, an etched mark, a Corelle or Fire-King backstamp, and iridescence if you tilted the piece and did not use a single overhead flash. It can show a green glow only if you photograph in the dark with the lamp in the frame or say, in words, that the glow was there. A daylight photo of yellow glass does not contain the glow. A phone will also invent a mint color that is not in the glass. Daylight, then the lamp, then the words.
A photo cannot hear a ring, run a lead swab, or tell you a dose. It cannot see the far side of a ruffled rim. It cannot name a Depression pattern from a stack of pink plates shot from above. Worth can recognize a form it knows when the mark or the pattern is in frame. It cannot taste lead, and it should not be asked to call a shiny bowl carnival, uranium, and Waterford in one breath.
Photograph the bottom, the rim, and one pattern detail. Then say which of the five questions you answered, and which you did not. The thrifting page is the aisle. Sold listings of that pattern, that color, and that chip are the price. A glow you did not test is not one of the words.