Is 275 degrees always 275 degrees?

[tommy2tone]

I had a clay blank that I made with some canes. It was Scuply and Kato. I baked in the toaster oven at 275. It started smoking and the blank started melting.. Maybe the oven temp really wasn't 275? The dial was between 250 and 300. Also I got in a hurry and didn't cover it (dumb mistake).

 

[sbwertz]

The problem with a toaster oven is that the material is too close to the heating elements, so that the overall temp of the oven may be 275, but the radiant heat may heat up the surface of the product much higher. You need to use a bigger oven where you can get the material farther away from the heating element

 

[1080Wayne]

Kind of looks like you put the mustard , relish and ketchup on the hot dog !

 

[Ed McDonnell]

I bought an oven thermometer and find that I have to use different dial settings on my toaster oven depending on the air temperature to get the oven temp I want. I turn the oven on and wait for the temp I want to register on the oven thermometer (adjusting the oven temp dial as needed) before I put anything in. It saves a lot of heartache.

Ed

 

[Cmiles1985]

This is good info. Now I know what to do to help my wife make some blanks for me

 

[KenV]

I have had a couple of toaster ovens -- one was off 75 degrees F from what the dial indicated. Thermostats in toaster ovens (especially low cost commodity models) are not a precision device -- and tend to get worse with age.

A better oven thermometer will likely cost more than the cost of a second hand toaster oven.

 

[Band Saw Box]

Got Put In Time Out

Do you have a way to check the temp of the oven to see how close it is.

 

[bobjackson]

I bake mine at 250 degrees for 30 minutes in a toaster oven.

 

[BRobbins629]

It is not uncommon for even full size household ovens to have air temperature variations of +/-50 degrees or more even if the average is at the set point. When the element comes on the interior temperature exceeds the set point and when off, it goes below. Only a good scientific oven will hold temperatures in a narrow range. That being said, if you shield the clay with a cover of foil, you should minimize chance of burning.

 

[Joe S.]

-85 degrees is the same thing.

 

[plantman]

First thing I can see wrong with your setup is the pan you have your blank set in. A 4 sided deep pan like that reflects and consentrates the heat back up toward your blank like a reflector oven would do. 2ed you need air to circulate around your blank. Cut a V groove in two wooden blocks to hold your rod and blank off the surface. You should also use the metal rack to keep your blank centered as much possable inside your oven and to allow air flow. 3ed Tin foil under and over your blank to reflect any hot spots away from your blank. 4th Go to Walmart and buy a oven thermometer, the stand up type, ($10) and place it inside the oven. Preset dials are never on the money. When your oven temp. reaches the degree you want, mark your dial for that setting. And last, I think 275 degrees is a little high, and unless you are doing a thick casting, 30 minutes is to long. I bake my polymar clay pen blanks at (true) 250 degrees for 15 minutes and remove them hot and submerge in cold water. Now you can dry them off and bring them directly to the lathe and turn. If they seem a little soft, return to the oven for another 5 minutes or so. I do a lot of inlays that require 2 heating cycles, one for the base color, and one for the inlay itself. Once your first heating cycle has been reduced back to room temp, and your inlay has been applyed, another 15 minutes of bakeing does not harm the blank. Jim S

 

[tommy2tone]

First thing I can see wrong with your setup is the pan you have your blank set in. A 4 sided deep pan like that reflects and consentrates the heat back up toward your blank like a reflector oven would do. 2ed you need air to circulate around your blank. Cut a V groove in two wooden blocks to hold your rod and blank off the surface. You should also use the metal rack to keep your blank centered as much possable inside your oven and to allow air flow. 3ed Tin foil under and over your blank to reflect any hot spots away from your blank. 4th Go to Walmart and buy a oven thermometer, the stand up type, ($10) and place it inside the oven. Jim S

Isn't it dangerous to put the wooden blocks in there? I will try what you say and get a thermometer also tin foil.

 

[Cmiles1985]

The temperature at which you bake the "clay" is nowhere near dangerous for wood. Wood needs a substantial amount more than 215-250 degrees to ignite.

 

[Pen-Archer]

I did the exact same thing last week and burned my first polymer blanks to a crisp. So I did some research.

The tips that plantman gave are good.

I would also add:
1. Make sure your toaster oven is set on bake not toast.
2. Again use a thermometer. I had to turn down my dial about 75 degs. to get 250 degs. Do this before you start cooking your blanks.

The next blanks that I cooked then came out fine.

 

[tommy2tone]

Thanks everyone. I did have have it set on bake. The metal rack was covered with foil. I will just use that instead of the tray. So 250 seems to be the norm? How many mins? I see 15 (Jims) and 30 (bobjackson)

 

[navycop]

Jeff, I think it depends on the clay brand. Some manufactures post the temp on the package. But maybe with the small amount we are using 250 might be a good number. The other guys can chime in on this as I haven't done any yet (only read about it).

 

[plantman]

First thing I can see wrong with your setup is the pan you have your blank set in. A 4 sided deep pan like that reflects and consentrates the heat back up toward your blank like a reflector oven would do. 2ed you need air to circulate around your blank. Cut a V groove in two wooden blocks to hold your rod and blank off the surface. You should also use the metal rack to keep your blank centered as much possable inside your oven and to allow air flow. 3ed Tin foil under and over your blank to reflect any hot spots away from your blank. 4th Go to Walmart and buy a oven thermometer, the stand up type, ($10) and place it inside the oven. Jim S

Isn't it dangerous to put the wooden blocks in there? I will try what you say and get a thermometer also tin foil.

Temp. is not high enough to ignite wood. Different brands of clay do recommend different temps. I have found that 250 and 15 minutes works well for me. The clay is still slightly soft when removed hot from the oven, so the dippng in cold water hardens the blank in the same manner that a knife or sword blade would be tempered. I usualy judge the time by the thickness of the clay, the thicker the clay the longer you would keep it in the oven. Also it is better to under bake the blank, as you can always reheat it. If you over bake it, there is no quick fix. I often mix different brands of clay together, so I don't find the difference in brands to be a big factor. Toni would have a better answer for time, mix, and temp, as she has been working in the medium for quite some time. Your blanks are interesting in themselves, I would turn them and fill any dips with CA and see what you have. You may be surprized. Jim S

 

[NittanyLion]

An oven thermometer is a must. When baking Cactus Juice at 200 degrees in my toaster oven, I always seem to need to adjust slightly based on my oven thermometer.

 

[mhbeauford]

I cure my stabilized blanks in a toaster oven and use as multimeter with a thermocouple thermometer. Toaster ovens are notoriously poor for temperature control. Your setting could be off by as much as 50-75 deg.

 

[Wood Butcher]

When I first started making PC pen blanks I acquired 2 used toaster ovens and when I baked the first batch of golfball blanks I set the control for 275 and the timer for 30 min. When done I allowed the oven to reach room temp before opening the door and, walla! the blanks were brown as in toasted. I made another set and fired up the 2nd oven and, with n oven thermometer in place, baked another batch. This one came out perfect. I looked over the first oven and realized that it had two sets of numbers, one is Fahrenheit and one Celsius. Yup, I was running a lot hotter than I knew. I'm sure no one else would make that silly mistake, would they? Sculpy (which I no longer use) at 275 and others at 235 FAHRENHEIT.
WB

 

[frank123]

It's pretty simple to just rig up a PID controller, a relay, and a long probe thermocouple that sets next to your blanks to measure and regulate the actual temperature of the blanks to within a degree or two of what you want even with a simple thrift store toaster oven.

Instead of trying to wire the toaster oven heating elements directly to the relay output rig it so that you feed standard mains power to a normal wall type plug so you can just set the oven to max, plug it in, and let the PID turn it on and off to regulate the temp using the main plug (this lets you use the oven timer if it has one).

Total cost using ebay scrounged parts should be well under 50 bucks, I think I have about 25 or so in mine.

Note that I'm assuming basic electrical competence, if you don't have it don't do it and risk electrocuting yourself or at least get some help from someone that does.

 

[MrsPTownSubbie]

Jeff, as many have already said, toaster ovens are much more difficult to regulate temperature. I prefer to use a regular oven in a similar aluminum pan for all my baking and have never had a problem with burning a blank. I do tent all blanks with aluminum foil.

If you look in the IAP library, Garie Sim did a few tests on toaster ovens to show how much variation there was with temperature readings - more info at The polymer clay :About baking polymer clay in the toaster oven.