Glasbake—originally known as Glasbak Ware—is ovenware made of glass. It’s known for its heat resistance. Glass in general is considered microwave-safe in that microwave energy isn’t usually absorbed by it.
There are exceptions though, like thin glass that can’t take the heat coming off of microwaved food. Glasbake is considered oven-safe glassware first and foremost.
Is Glasbake Microwave-Safe?
Glasbake is a line of heat-resistant serving ware, baking ware, and ovenware developed at the beginning of the 20th Century or the early 1900s by the McKee Glass Company. If something is heat-resistant enough to be oven-safe then surely it should be microwave-safe, right?
Not necessarily. Even though later on, modern Glasbake Kitchenware pieces have gotten the microwave-safe label of guarantee, earlier dishes weren’t necessarily designed for microwave safety. Like with everything else with the label, it assures you of safe microwave usage.
However, vintage or antique Glasbake might work fine in an oven but they might get superheated inside a microwave.
Which Glasbake Dishes are Microwave-Safe?
As per usual, any Glasbake item with metal handles and whatnot shouldn’t be put inside the microwave as a matter of course (metal isn’t microwave-safe and can cause electrical sparks or overheating to happen).
However, certain vintage or antique Glasbake items might unduly absorb microwaves or end up unable to handle the hotness of microwaved greasy food, thus increasing their risk of thermal shock (when a hot glass dish has its temperature suddenly drop, it typically breaks apart).
If you’re uncertain of the age of the Glasbake dish you’re using, you can test its microwave ability by microwaving a cup of water on the dish then checking if the dish remains cold (microwave-safe), warm (for reheating only), or not (unsafe for microwave use).
You may also like: Can You Microwave Glass?
How to Specifically Test If the Glasbake is Microwave-Safe?
To elaborate on the cup of water testing method, it involves microwaving the Glasbake dish with the mug or cup of water with it at full power for a full minute.
Alternately, you can use cold water instead of tepid water to do the test and wait until the water is boiling before taking the dish out. The cup used can also be a microwave-safe measuring cup that handles 2 cups of water instead of just one.
The Dish Should End Up Cold, Warm, and Hot
If the dish remains cool even as the water gets hot, it’s microwave-safe. If the dish gets warm while the water ends up hot then it should only be used for reheating instead of cooking or lengthy heating sessions at full microwave power.
If the dish gets as hot as or hotter than the cup of water then it’s not microwave-safe at all. You should never use it for microwaving because it’s most susceptible to thermal shock, breakage within your microwave, or becoming superheated.
Can Glasbake Be Used in a Conventional Oven?
The Glasbake line—even antique Glasbake dishes and bowls—was designed for use in the oven for cooking things like a whole turkey or festive Christmas ham as well as baked macaroni and lasagna because it doubles as a serving dish afterwards.
That’s what the Glasbake or Glasbak Ware line was originally designed for. It’s a glass baking dish for glass serving afterwards. These pieces made from 1917 to 1983 come in various patterns and can be availed of in flea markets and collectibles.
Don’t use bakeware for temperatures above 375°F to 400°F as a precaution. They can technically take 450°F of heat but you’re really pushing their limits beyond that.
How to Test If Any Dish is Microwave-Safe?
Just use the cup of water method. This applies to all dishes. Microwave the dish and the cup for a minute. The water inside the cup alone should be hot. If the container or dish is warm or hot after it’s been heated then the dish or container isn’t microwave-safe.
The dish, whether it’s Glasbake or Pyrex otherwise, should remain cool. Only the food or beverage should be hot. If the dish gets as hot as the food, it risks making the food hotter to the point of burning or suffering from thermal shock.
Further reading: Can You Microwave Pyrex? Here are the Facts
Is Glasbake Like Pyrex in Any Way?
Glasbake is usually overlooked in favor of Pyrex, Fire King, Luminarc, or even Arcopal. Glasbake can be considered as Pyrex’s cousin in that they’re related but Pyrex is the superior heat-proof glassware. Both are made of glass but the quality of glass varies between the two brand lines.
Glasbake has been around for a long time. It was originally named Glasbak Ware but all throughout its existence it has made its signature decorative glassware. Their brand of glassware is made of pressed glass, jadeite, white milk glass, or black glass.
They’ve even manufactured headlight lenses for good measure (glass lenses as opposed to the plastic ones nowadays).
What Types of Dishes are Microwave-Safe Anyway?
Ceramic and glass dishware are usually safe for use in the microwave. So much so that many people assume any chinaware or glassware is microwave-safe when technically the FDA recommends that like with plastic containers, you should only use dishware with the “microwave-safe” logo on it.
You can always test the ceramic plate or glass serving ware to ensure you can safely put it inside the microwave and not have it break due to thermal shock and heat stress from the food that’s being heated or cooked.
The exceptions to this rule of thumb Is usually handmade jewelry and glass crystal ornaments. Most bakeware, mixing bowls, mug, cups, bowls, and plates are perfectly at home for use in the microwave unless they aren’t particularly heat-resistant.
Some Final Words
Any Glasbake item with the microwave-safe label can be microwaved safely unless the dish has somehow been compromised by daily use (micro-cracks and fractures or a preexisting crack that could be exacerbated with microwave cooking or leftover reheating).
Any antique Glasbake item made before the dawn of microwaves in the 1950s and 1960s (and doesn’t have the microwave-safe label) should be tested as microwave-safe first using the cup of water test before being used regularly.
If the label isn’t there, it’s safe to presume that the Glasbake dish, bowl, or serving ware is simply not microwave-safe to err on the side of caution.
- “Bakeware’s Underdog – Glasbake vs. Pyrex“, WhipseringCityRVA.com, January 31, 2020