forgot the foil

[RAdams]

Well i tried to help my wife make a polymer clay keychain today. By that statement, and the title, you can guess that i burned the PC beyond belief. It turned a horrible black color all over, and even had one spot where the PC had actually started burning (bubbling and blistering). I think i will retry it again soon, only this time i will not forget to cover the PC. I need to devise a rack for my little oven...


Anyway, Just thought i would share what happens if you forget the cover.

 

[el_d]

Cover???

What cover? What you talkin about Ron?

 

[RAdams]

I read somewhere that you are supposed to make a foil "tent" to cover the PC while it bakes.


but now i think my problems are bigger than that. I just did another one with a foil cover and got very similar results. I have also noticed that everyone seems to have different temps and times for baking.

The package said 300 degrees for 10 minutes. That failed. A video i was able to watch part of mentioned 275 degrees for 30 minutes, which also burned the clay. I dont want to waste anymore of my canes burning stuff so i will sit and wait for our resident PC specialists to give me a shout... HELP!!!!!!!!!!!!!! how long and at what temp???

 

[dexter0606]

Ron
Make sure of the cooking times. The PC that I have used (Preemo & Scuply III) all said XXX degrees per 1/4" material thickness. And I've never "tented" them although I have only done this about 6 times.

 

[RAdams]

yeah my wrappers dont say anything like that. Just bake at 300 degrees for ten minutes. That is false for sure.

 

[CaptG]

Ron, I use Premo and bake at 275 for 30 minutes under a foil tent. Sounds like your oven is running hot, put a thermometer in and check the cooking temp.

 

[dexter0606]

Gary
Like I said I'm no expert at this but I believe that the time depends on the thickness of the material. I've wrapped PC around brass tubes and cooked them a lot less time than a 1-1/2" diameter piece I did for a winestopper blank

 

[workinforwood]

I tried one, sculpey clay, on a tube, 275 for 30 minutes and no tent. worked fine.

 

[CaptG]

Gary
Like I said I'm no expert at this but I believe that the time depends on the thickness of the material. I've wrapped PC around brass tubes and cooked them a lot less time than a 1-1/2" diameter piece I did for a winestopper blank

No argument about the time, but I think the heat is the problem. The other night I baked a necklace set which has a very thick clay on the top tube, two slims and a sierra all at the same time with no problems at 275 for 30 minutes, using preemo. A while back I tried some tubes at 300 for 20 minutes and they came out looking like they were fresh from the litter box.

Ron, I also seal the foil tent at the sides and close it off on the ends. That has helped me also.

 

[el_d]

275, 300 degrees??

The skulpeyIII I got said 130deg for 15 min for eack 1/4 of thickness. Said so on the package.

 

[lazyguy]

Ha foiled again.

I believe I read that the foil tent was to trap the residue that is put off whilst the clay bakes. While I have not had sucess with it I have yet to burn any in my attempts. So like mentioned before you might want to get an oven themometer.

 

[RAdams]

i will check it now! thanks for the heads up!!

 

[dexter0606]

The skulpeyIII I got said 130deg for 15 min for eack 1/4 of thickness. Said so on the package.

That's 130 degrees C or 275 F

 

[Russianwolf]

yes, do not exceed the temp listed on the package. you can bake it longer with no ill effects, but too hot and it will burn. A cheap oven thermometer costs less than $5 and helps you make sure your oven is accurate.

 

[el_d]

That's 130 degrees C or 275 F

Wow I actualy ripped the package open and didnt see that:redface:

 

[CaptG]

275, 300 degrees??

The skulpeyIII I got said 130deg for 15 min for eack 1/4 of thickness. Said so on the package.

You are right, but that is 130C (celsius) which is 275F (fahrenheit).

 

[CaptG]

Oops, Jeff was faster, I had to look up how to spell fahrenheit, lol.

 

[RAdams]

Oops, Jeff was faster, I had to look up how to spell fahrenheit, lol.

"F":biggrin:




I do indeed think i burned it by cooking too hot. My oven runs about 25 or 30 degrees hotter than the thermostat reads.

 

[jskeen]

Another thing to consider, if you are using a toaster oven instead of a big one, is that the fact that the heating rods are so much closer to the clay means that the temp is very uneven from spot to spot, and also that the radiant effect can produce much higher surface temps than the ambient air temp in the oven. Try to move as far away from the elements as possible, and consider adding a foil barrier between the elements and the rack. Then get a good over thermometer, tape over the temp readings on the selector dial, and recalibrate it to the actual temp at the spot you are going to put the blank, and write the new temp on the tape. I bet it will be way off what the dial shows. DAMHIKT

 

[RAdams]

I was concerned about that. My wife and I were talking about that very thing last night. I think i am going to try to do a couple of simple mods to the oven to make it cook more even and accurately. With no heat diffuser, the thermometer read 30 degrees hotter than the knob, which put me up somewhere around 350 or 375 when i tried to bake.

The second blank came out better, but i turned the temp down to 275, which is what the milly vanilly (or whatever it was) lady said to do. Next time I will use the thermometer to get it right on the temp part!


OTHER THINGS I HAVE LEARNED:

Cutting a thin slice is easy. cutting an even slice is easy. Cutting a thin, even slice is IMPOSSIBLE.

It is very very difficult to start with a small amount of clay to make a cane. At first i thought it was insane to start with pounds and pounds of clay to make one cane, but after messing with it some, I understand why the cane makers start with 10 pounds of clay! I tried to make a cane with four ounces of clay. What a joke that was. Impossible to get any knd of detail at all, and i am just trying to do a profile shadow type picture inside the cane. I cant imagine trying to make a flower.

I also learned that PC turns like butter. I have heard other people say this when turning certain materials, or you hear it alot when the woodchuck owners talk about there tool. I never experienced the "Butter" until i turned some baked PC. Ribbons instantly, and the material was cut below the bushing before i could do anything about it. I learned the true definition of a light cut!!!

 

[CaptG]

Ron, I forgot to mention that the rack that holds the tubes upright does sit on a tray in the toaster oven and that likely diffuses some of the heat indirectly.

 

[RAdams]

Yeah, mine has a lower rack as well, Just nothing to diffuse the top burner. I used a piece of steel wire and formed a "stand" for one tube. I then put an international coffee can over the top of it. It worked out ok, but only half way through the 30 minutes i checked it, and the translucent clay was starting to turn brown. You can see it kinda in the pics.

The first pics is the completed keychain. No finish, just sanded.
The second pic shows where i turned it too low and got into the base clay.
The third picture is just to try to show off the amazing detail in Toni's canes.

 

[RAdams]

I forgot to mention, I call this keychain my second failure. My wife calls it my first success.

 

[Smokey7385]

Burn baby burn.

I was having a lot of trouble burning my PC too and Toni came to the rescue. If you get a oven thermometer DO NOT get the Sculpy one. Go to Wal Mart or Target and get one of thier cheap ones. The Sculpy thermometer was off (reading lower) by 25-30 degrees.

Next; vary the time you bake depending on the thickness of the clay. With a wrapped tube the clay is quite thin, less than 1/8" sometimes and the baking instructions are for a 1/4" piece of clay. With the new cheap thermometer and my baking time reduced to 20 min. I have not had any burns since. On my last PC pen I tried 25 min with no problems which leads me to think that the thermometer has a greater affect than the amount of time.

Threre is some good info here as well:
http://polymerpenmaking.ning.com/

 

[creativewriting]

Man you guys get some crazy information from places. The keys to curing PC are 1.) oven thermometer 2.) preheating the oven 3.) consistant even temperature. I have a toaster oven in the garage that cures all my PC needs. I didn't skimp on the oven ($50 or so). It is a convection oven with an element on the top and bottom. Some of the less expensive ovens lose temperature fast and the elements are always glowing red. THIS IS BAD:doctor:! Clay cures between 250 and 300 based on the brand. I usually set the oven to 275 and fire everything. All of my pen blanks I fire for 30 minutes. Most of them are less then a quarter inch thick, but I like the little bit of extra time. I check the oven thermometer about every 5 minutes or so to make sure the temp. is still in the 275 -290 range. At 300 your colors will darken a little depending on the brand.

The foil tent is recommended only if you are firing the clay in your home oven. It traps the residue even though very little is omitted from the clay. Some folks bake piece inside of dedicated casserole dishes with lids, but I have never had sucess with that method.

Good luck and quit burning stuff:biggrin:

 

[nava1uni]

You should put the clay on a non metallic surface for even heating, I use a piece of tile I bought at HD for 16 cents. I have found that if I chill the clay is is easier to cut thin slices. I cut the clay with a very fine blade that is made by Sculpey. I can get very thin slices. I use an oven thermometer

 

[creativewriting]

Try one of these if you get out to your local craft store. The rack is designed for beads. It comes with small rods that I put throught the brass barrel and suspend the blank while baking. Depending on the thickness of the barrel you can bake quite a few off at a time. I usually put a blank every other space so they don't rub. For slims you may be able to bake in every slot. Use a 40% coupon and the rack is under $10.

It also comes with an acylic piece slides in the bottom. This is to help with cane slicing. Your cane sits on the acrylic and slides to the end. You then use the end of the rack as a guide for your blade.

 

[Toni]

Just read this book I suggest a tent for the reasons mentioned above....

As Rusty said get a real oven thermometer, cheep ones are just that cheep and not reliable.

Pre-Heat the oven and Ron I think your second pen came out great I have to agree with your wife!!

Keith excellent recommendations(of coarse)!!

 

[RAdams]

I was wondering when you were gonna get to it Lady:biggrin:!

Thanks for the compliment! It is actually just a keychain.

I did another one after that one, A Sierra this time. It is on the lathe waiting for me to sand it. For some reason the colors are fine, but the translucent parts turned a brownish color. I dont know whati am doing wrong.

I used an meat thermometer and a metal can over the blank, but i messed up on the temp. I was paranoid about burning it, so i cooked it at about 230 for 30 minutes with no cover. The translucent parts were still a whitish color, so i turned the heat up to about 270 or 280 for 15 minutes and put the metal can over it. When i returned, the translucent parts were brown.

I am using a toaster oven that is a mid grade toaster, but it is very small. It is a dedicated chemical toaster, so the fumes inside aren't an issue. The toaster has two elements, One on top and one on bottom. They are not the regular wire elements. There is a single tube running across the top ad another across the bottom. The element is inside this tube. There is a metal pan on the bottom to hold the "food" and a small metal deflector thingy on top between the "food" and the element.

I am confident that i could be successful with a burl type blank, but for some reason the canes are giving me a hard time.

 

[RHossack]

I read somewhere that you are supposed to make a foil "tent" to cover the PC while it bakes.

you sure the temp is correct? The dial may say one thing but the innards may say something else ... put a thermometer in there and check.

 

[RAdams]

I set the dial and used a meat thermometer. I am not sure what the problem is. I will figure it out eventually!

 

[Russianwolf]

I set the dial and used a meat thermometer. I am not sure what the problem is. I will figure it out eventually!

don't use a meat thermometer, use an oven thermometer. It literally sit on the shelf. the meat thermometer can be inaccurate since it is trying to measure the inside of something with the metal spike, if it touches the metal shelf it may not read right.

 

[RAdams]

well there is my problem right there! Thanks for the tip! I never thought i would be shopping in the cooking department when i started making pens! Funny stuff!!

 

[creativewriting]

I think your metal can may be doing you in as well. It is trapping way to much heat. Foil is designed to release its temp. You can usually grab foil as soon as it comes out of the oven (and we use some pretty heavy duty stuff in my kitchens). The can will not release the heat as quickly and burn your item.

Ditto on the meat thermometer!