Strange things are happening

[Alpo]

My dishes are Pfaltzgraff. According to their website they are salt glazed, whatever that means.

 

I have a 12 cup coffee pot. I drink two - maybe three cups of coffee in a day. So the next day I pour myself a cup of the cold coffee and nuke it.

 

My coffee cup used to get so hot in the microwave but if I tried to remove it with my right hand it gave me first degree burns. if I took it out and tried to carry it into another room, by the time I got where I was going I had second-degree burns.

 

 

It was hot - just in case someone didn't recognize what I meant.

 

That only happened with my Pfaltzgraff cups. I have some Churchill Blue Willow. The cups never got hot. I have some plain generic white ceramic cups. They also never got hot.

 

That was with my right hand. If I took it out with my left hand it was still hot, but it did not cause me physical damage.

 

That's the first strange thing. If it's hot, then it's hot. Why should which hand I use make a difference?

 

For the last few months the cup has not been hot. The coffee is still just as hot as it used to be, but the cup is just slightly warm, as you would expect a cup full of hot liquid to be.

 

That is strange.

 

My 12-cup coffee maker actually makes (in real world coffee cups) about 4 and 3/4 cups. I would get for full cups, that get nuked for 2 minutes, and finishing off the pot would give me about 3/4 of a cup which only gets nuked for a minute 30.

 

This last part I got 5 full cups. Where did that last quarter cup of coffee come from?

 

Again - strange.

[Tascosa, SASS# 24838]

I have a 12 cup coffee pot. I make 8 cups and that is one cup for me and 2 for my wife. When she is on a cruise with my daughter, I make all 12 cups and nuke  em in our glass mugs. The mug never gets hot. Oh ifn yer wondering why I don't go on the cruise, I have to stay home with our dog. Life is so unfair...

[Cat Brules]

“Most unusual, Watson.”

 

“Yes, Holmes, all of it!”

 

 

Cat Brules

 

 

 

[Forty Rod SASS 3935]

I may be strange.......STOP THAT LAUGHING.......but I would greatly prefer staying home with my dog than go on a cruise any day.  Less crowded, less noisy, less expensive, less rude people to deal with, no currency differences, no language barriers, no customs, no borders to cross, and no strangers wanting to talk to me.

[Cold Lake Kid, SASS # 51474]

Try Holland America.

SWMBO and I found their ships and people more to our liking.

They seemed to cater to an older crowd; smaller "Vista" ships etc.

[Utah Bob #35998]

You lost me at nuked day-old coffee!! LIfe's too short for that.

Get a single cup maker.

[J-BAR #18287]

How thick are the walls of the Pfaltzgraff cups?

 

Heat is being transferred from the water to the cup while in the microwave oven.  Thick walled cups will be better insulators than thin walled cups.  The water/ coffee should boil faster in a thin walled cup because when the temperature of the cup and water equilibrate, all the microwave energy is being absorbed by the water, not the cup.

 

 I suppose Pfaltzgraff could use a different/special ceramic with a dramatically different heat capacity than ordinary ceramics... you could  have fun experimenting with that.  

[Alpo]

It's not the walls of the cup that was burning me. It's the handle.

 

 

Under my thumb it would be hot. On the side of my index finger it would be hot. But on the side of my middle finger is where it would burn.

[Alpo]

34 minutes ago, J-BAR #18287 said:

 I suppose Pfaltzgraff could use a different/special ceramic with a dramatically different heat capacity than ordinary ceramics..

That's why I mentioned that the website says they are "salt glazed". I don't know what that is, and I don't know how that would be different from any other ceramic glazing. But possibly that's why it was hot.

 

And it wasn't just the cups. For a while my stove was broken. I cooked with microwave, toaster oven, and crock pot.

 

And I discovered that a fine way to cook hot dogs was to put a couple paper towels down on a plate, lay the hot dogs on the toweling, cover them with a third towel and nuke.

 

If I did this with one of the Pfaltzgraff plates, I would need a hot pad to take it out of the microwave. I've also got a couple of cheap generic stoneware plates but I've had for 30 years or so. They were never hot if I used them for hot dog cooking.

 

My puzzlement takes two forms.

 

Why did these dishes get so hot, when other ceramic dishes didn't?

 

And why don't they get this hot anymore? Because they've quit.

[Cypress Sun]

2 minutes ago, Alpo said:

That's why I mentioned that the website says they are "salt glazed". I don't know what that is, and I don't know how that would be different from any other ceramic glazing. But possibly that's why it was hot.

 

And it wasn't just the cups. For a while my stove was broken. I cooked with microwave, toaster oven, and crock pot.

 

And I discovered that a fine way to cook hot dogs was to put a couple paper towels down on a plate, lay the hot dogs on the toweling, cover them with a third towel and nuke.

 

If I did this with one of the Pfaltzgraff plates, I would need a hot pad to take it out of the microwave. I've also got a couple of cheap generic stoneware plates but I've had for 30 years or so. They were never hot if I used them for hot dog cooking.

 

My puzzlement takes two forms.

 

Why did these dishes get so hot, when other ceramic dishes didn't?

 

And why don't they get this hot anymore? Because they've quit.

 

Maybe there is some minute parts of metal in that make of china?

[Subdeacon Joe]

Salt glaze is the process of introducing salt into the kiln at certain points in the firing.  The salt breaks down and reacts with the clay body to form a glaze.  It is usually a kind of pebbled surface. 

 

Pfalzgraf uses a high iron clay in a lot of its ware.  This gets hot in the microwave. 

[Cactus Jack Calder]

Hot Cups:
1. Do yo use a dishwasher to clean your coffee cups? 

2. If not do you soak them in a dish tub?
3 Look at the bottom of the Pfaltzgraff cups, does the glaze not cover the entire bottom (this is the most usual way ceramic cups are made)? 
 

It is likely that moisture has wicked into the ceramic core of the cup. Microwave ovens heat items by vibrating the water molecules to create friction on a molecular level. Think rubbing two sticks together to start a fire (good luck with that ).  The moisture in the ceramic core may have finally dried out, allowing the heat of the coffee in the cup to radiate through the ceramic. The radioing of heat through the ceramic is a much slower process. Therefore on burning fingers.

 

Right hand vs Left hand sensitivity: 

It is possible that you right hand, being your dominant hand, has built up a tougher layer of skin. Not exactly a callus but similar in nature. I know I can drink some hot fluids that would make my jerk my hand back without damaging or causing pain to my tongue. The sensitivity of various parts of our body seems to be adjust to how they are used.

 

CJ

[Cactus Jack Calder]

4 minutes ago, Cactus Jack Calder said:

Hot Cups:
1. Do you use a dishwasher to clean your coffee cups? 

2. If not do you soak them in a dish tub?
3 Look at the bottom of the Pfaltzgraff cups, does the glaze not cover the entire bottom (this is the most usual way ceramic cups are made)? 
 

It is likely that moisture has wicked into the ceramic core of the cup. Microwave ovens heat items by vibrating the water molecules to create friction on a molecular level. Think rubbing two sticks together to start a fire (good luck with that ).  The moisture in the ceramic core may have finally dried out, allowing the heat of the coffee in the cup to radiate through the ceramic. The radiation of heat through the ceramic is a much slower process. Therefore no burning fingers.

 

Right hand vs Left hand sensitivity: 

It is possible that you right hand, being your dominant hand, has built up a tougher layer of skin. Not exactly a callus but similar in nature. I know I can drink some hot fluids that would make my jerk my hand back without damaging or causing pain to my tongue. The sensitivity of various parts of our body seems to adjust to how they are used.

Dad blamed otto korekt.

 

CJ

 

[Alpo]

38 minutes ago, Cactus Jack Calder said:

Right hand vs Left hand sensitivity: 

It is possible that you right hand, being your dominant hand, has built up a tougher layer of skin. Not exactly a callus but similar in nature.

Thought about that. Except it's the other way. My Dexter hand is more sensitive to the heat than my Sinister hand.

 

As to washing them - no and no.

 

Yes, the very outside of the bottom is not have a glaze on it.

 

Maybe, during the summer, when the humidity is in the high 120s, they absorb moisture out of the air, and thus burn me, but in the winter time when the humidity is down around 40, less moisture is absorbed by the dishes, so they don't get as hot.

 

Even though that theory is mine, I have to admit, it's reaching.

[Tascosa, SASS# 24838]

3 hours ago, Forty Rod SASS 3935 said:

I may be strange.......STOP THAT LAUGHING.......but I would greatly prefer staying home with my dog than go on a cruise any day.  Less crowded, less noisy, less expensive, less rude people to deal with, no currency differences, no language barriers, no customs, no borders to cross, and no strangers wanting to talk to me.

That's exactly why Im staying at home with my dog.

[Pat Riot]

Those cups are not microwave safe. Bottom line. Use different cups.  
 

Now as for your hands feeling hot temps or not feeling hot temps, I recommend you tell your doctor what you told us. You may have some nerve issues. 
 

My 2 cents. 

[MizPete]

8 hours ago, Subdeacon Joe said:

Pfalzgraf uses a high iron clay in a lot of its ware.  This gets hot in the microwave. 

This comes as good news to me as I, too, use Pfaltzgraf (Heritage, no longer made) and always assumed it was lead. 

[Forty Rod SASS 3935]

7 hours ago, Tascosa, SASS# 24838 said:

That's exactly why Im staying at home with my dog.

It has worked for me (most of the time) for over sixty years now.  I got caught a few times early on and that solidified my feelings to match yours perfectly.

[Subdeacon Joe]

1 hour ago, MizPete said:

This comes as good news to me as I, too, use Pfaltzgraf (Heritage, no longer made) and always assumed it was lead. 

 

As a gross generalization you don't have to worry about lead in most high fire ware.  The problem with lead leaching is pretty much only in the low fire earthenware, usually Mexican or South American, or some of the very ornate oriental ware that has low fire glazes over the high fire glaze.

More on saltware:

https://ww2.kqed.org/quest/2011/10/27/science-on-the-spot-the-science-of-salt-glaze-pottery/

https://en.wikipedia.org/wiki/Salt_glaze_pottery

 

Quote

Process[edit]

 

Pouring salt into a wood-fired kiln, using a carved-out piece of bamboo filled with salt soaked in water.

 

Modern salt-glazed porcelain piece

The salt glaze is formed on the unglazed body by reaction of common salt with the clay body constituents, particularly silica, toward the end of firing. The body should ideally be richer in silica than normal stoneware, and iron impurities can help produce good salt glazes. A reduction atmosphere can be employed as the reduced iron silicates are very powerful fluxes.

The salting mixture of sodium chloride and water is introduced into the kiln when the appropriate temperature is reached, typically around 900 °C. As the kiln reaches higher temperatures, typically 1100–1200 °C, the sodium chloride vaporizes and reacts with steam to form hydrogen chloride and soda. These vapors react with the silica in the body and other body constituents. A glaze of fairly high alumina content (0.6 molecular parts) and a relatively low silica content (2.6 molecular parts), and in which the main base is soda, is formed. Salt glazes have been improved by the addition of borax, and sometimes sodium nitrate, to the salting mixture. Colouring oxides can be incorporated in the salting mixture to give decorative effects, such as a kind of aventurine glaze.^[28]

Salt fumes in a firing atmosphere react in the following way:

2NaCl + 2H₂O → 2NaOH + 2HCl

2NaOH → Na₂O + H₂O

In soda firings the reaction is a little more direct, not requiring the presence of water vapor:

Na₂CO₃ → Na₂O + CO₂

Both the hydrogen chloride and the carbon dioxide are gases; they do not react with the sodium oxide that binds with the silica and other components of the clay body. Hydrogen chloride leaving the kiln will form a hydrochloric acid vapour on contact with moisture in the air or kiln exhaust gases. Any remaining sodium oxide will form salt by reacting with hydrochloric acid vapour as the gases exit the kiln. The sodium oxide (Na₂O) reacts with the alumina and silica in the clay body to form a sodium alumino-silicate glaze.^[1] The general reaction is shown below, with the values for x and y varying dependent on the amounts of sodium oxide, alumina and silica composing the glaze:

Na₂O + SiO₂ + Al₂O₃·(SiO₂)₂ → (Na₂O)_x·Al₂O₃·(SiO₂)_y

Salt can also be used as a decorative element on selected individual pots. Biscuit ware can be soaked in a brine solution to create salted patterns. Rope and other textiles can also be soaked in brine and wrapped around biscuit ware. Salt can also be added, in solution, to coloured clay slips and can be sprinkled onto biscuit ware in protective, ceramic containers called saggars. A related technique, soda firing, substitutes soda ash and/or sodium bicarbonate for common salt. Whilst the application method is a little different, the alternatives need to be sprayed into the kiln, results are similar to salt glazing but for subtle differences in texture and colour.

 

[Sedalia Dave]

4 hours ago, Pat Riot, SASS #13748 said:

Those cups are not microwave safe. Bottom line. Use different cups.  
 

 

 

Some ceramic cups and plates are microwave safe and others are not.  We have a lot of Fiesta Ware and while microwave safe it does heat up if put into the microwave all by its self.  Nice feature as I can warm our plates before I put food on them. Helps keep hot food hot.