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Author Topic: Talking of Maggie Maggio - Polymer Clay Chain tutorial  (Read 10159 times)

ejralph

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #15 on: May 12, 2011, 07:22:59 AM »
In my experienced, you do need to reach the recommended baking temp for the clay to cure strong enough, sometimes even a tad higher. And a few degrees can make a world of difference.

When the Fimo formulation changed, I spent a lot of time experimenting on this.

I was having a problem where round beads were developing hairline cracks if I baked the new clay at the old temp of 130. Tried everything I could think of - different ovens, different thermometers etc.

Anyway, I concluded that for balls of clay, I do indeed need to follow their instructions and only bake to 110. If i do that, balls (and that means beads of course!) come out perfect. Well baked with no cracks.

The relevant part to this conversation however. I found that thinner sheets, sticks etc of clay would still be quite brittle at 110 degrees. (All my tests were carried on on test tiles cut from sheets of clay on a medium pasta machine setting )

If I cooked them at 110 - they would snap clean in half when I tried to bend them. If I cooked them at 125 / 130 degrees  it was a different story. The clay piece would be flexible and hard to break. It would take an effort to snap it in half and the clay would even develop those white stress lines before it went (like when you try to break a credit card in half by hand)

So temperature playes a bit part in the final strength of the baked clay.

I found that for Fimo - I get optimum results if I bake flat pieces at 130, but beads and solid items lower at 110.

Doing some tests like this on the clay you are using might give you a whole new perspective on how to best bake it.

The testing is simple and can be done alongside any "real" claying. Just make some pieces that are flat, round and pencil-thin log shaped and make them with the temp you will be baking at. Then when they are baked and cool, observe them for cracks and other note-worthy results, then set about destroying them!

Do the same shapes and bake slightly higher temp - see what happens. Is the clay stronger?

Emma
Emma from Sunny Sussex, UK
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shelleym

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #16 on: May 12, 2011, 10:51:11 AM »
That's interesting Emma - I had a batch recently - round beads that almost all came out with hairline cracks. No idea which clay I use, I'm terrible, I use a complete mixture of whatever I fancy at the time. mostly Premo and fimo mix to get the right consistency. But I thought I still had all 'old formular' stuff and baked at about 130. Flat pieces were fine, but thicker junkier pieces (couple of larger pendants) and most of the beads had tiny hairline cracks. Now I have the oven in the same room as I'm working I can keep checking temperature (I always have the thermometer in there with them) - I even have a torch now so I can shine it through the door and peek at the thermometer without opening the door to see the temperature as I put the thermometer towards the back of the tray. First time I've had problems. So perhaps with beads like that I'll bake a bit lower. But I'm fairly sure it was all old stuff, none of the new temp. stuff, but then as I mix so much of it, some of the newer stuff may have snuck in there.

I can't keep track of various temperatures any more and what needs to be baked at what temperature!

Shelley



shelleym

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #17 on: May 12, 2011, 11:21:57 AM »
Attaching a picy of said duff/cracked beads. Bit miffed about the large one, the front is fine, but the back is really well cracked. The small beads have really really tiny hairline cracks.
Shelley

rubyrube

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #18 on: May 12, 2011, 01:59:52 PM »
Shame about the beads Shelley, they are lovely. Are you not able to do a bit of carving and back filling over the areas? Might be worth a try if you can't use them anyway.
Carol
Carol

ejralph

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #19 on: May 12, 2011, 02:36:40 PM »
That looks like the type of cracks I was talking about Shelley.

I think it happens when the outside cures completely and the inside is still expanding.

I agree with the backfilling idea, make a feature of it, because its very hard to disguise the cracks with liquid clay etc.

Emma
Emma from Sunny Sussex, UK
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shelleym

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #20 on: May 12, 2011, 04:23:16 PM »
The pendant I was wondering about putting a completely new back on it in black - not sure though, might make it too chunky. I hadn't thought about back-filling. I've sort of consigned them to the 'trash' pile at the mo. What did you do with yours emma? The mix in the middle core of the beads could have been of any clay - just scraps - perhaps it just wasn't compatable temp wise with the layers over the top. Who knows! I'll just be more careful in future.
Shelley

LizzyClare

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #21 on: May 12, 2011, 04:27:09 PM »
Thanks for your kind comments on my necklaces.

I haven't had any strength problems. They were made with Premo and the coils weren't too thin. Make sure that you link the beads whilst they are still hot (wearing oven gloves!). Once they start cooling down it is harder to link them together. If you try and do it once they are cold then you will have problems. You can always pop them back in the oven to warm up again.

rubyrube

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #22 on: May 12, 2011, 06:06:05 PM »
Make sure that you link the beads whilst they are still hot (wearing oven gloves!). Once they start cooling down it is harder to link them together. If you try and do it once they are cold then you will have problems. You can always pop them back in the oven to warm up again.
Good tip, thanks.
Carol
Carol

polynana

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #23 on: May 12, 2011, 06:56:47 PM »
What a shame Shelley, I'd try to make a feature of the cracks too, the type of pattern you have on them lends itself to that.

I love that with our polymer beads we can repair them unlike with glass

KMD

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #24 on: May 12, 2011, 07:22:37 PM »
In my experienced, you do need to reach the recommended baking temp for the clay to cure strong enough, sometimes even a tad higher. And a few degrees can make a world of difference.

When the Fimo formulation changed, I spent a lot of time experimenting on this.

I was having a problem where round beads were developing hairline cracks if I baked the new clay at the old temp of 130. Tried everything I could think of - different ovens, different thermometers etc.

Anyway, I concluded that for balls of clay, I do indeed need to follow their instructions and only bake to 110. If i do that, balls (and that means beads of course!) come out perfect. Well baked with no cracks.

The relevant part to this conversation however. I found that thinner sheets, sticks etc of clay would still be quite brittle at 110 degrees. (All my tests were carried on on test tiles cut from sheets of clay on a medium pasta machine setting )

If I cooked them at 110 - they would snap clean in half when I tried to bend them. If I cooked them at 125 / 130 degrees  it was a different story. The clay piece would be flexible and hard to break. It would take an effort to snap it in half and the clay would even develop those white stress lines before it went (like when you try to break a credit card in half by hand)

So temperature playes a bit part in the final strength of the baked clay.

I found that for Fimo - I get optimum results if I bake flat pieces at 130, but beads and solid items lower at 110.

Doing some tests like this on the clay you are using might give you a whole new perspective on how to best bake it.

The testing is simple and can be done alongside any "real" claying. Just make some pieces that are flat, round and pencil-thin log shaped and make them with the temp you will be baking at. Then when they are baked and cool, observe them for cracks and other note-worthy results, then set about destroying them!

Do the same shapes and bake slightly higher temp - see what happens. Is the clay stronger?

Emma
Now I'm confused and embarrassed :-[!

I've rushed home to check my clay as I thought the same as Shelley i'm mixing, I thought I was using the new formula and it was supposed to be 110 c but I have checked all my new ones and old and they all say 130 c so confession I have been baking at 110, so Emma where have I gone wrong? if you want to move this to another thread then please do!! all my round beads and thicker pendants have been perfect no hairline fractures,

As we speak my oven is on at 130c and i have testers to go in I should get them baked before I go back to work for another shift!!
Karen

ejralph

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #25 on: May 12, 2011, 09:10:19 PM »
Remember we have been discussing two different problems, at either end of the scale -

1 - thin sheets of clay not being strong enough : probable cause, not baking hot enough. Probable solution - check temp is correct with oven thermometer and maybe try increasing by 5 or 10 degrees.

2. Balls or thicker bits of clay getting hairline cracks : probable cause, baking a bit too hot. Probably solution - again, check oven temp with reliable thermometer to ensure you are not baking hotter than you realise. Try dropping temp 5 or 10 degrees.


Generally speaking, the clay needs to *at least* reach the recommended baking temp on the packet. And for thinner pieces, you can usually up the temp a few degrees above that and the clay may be stronger for it.

Emma
Emma from Sunny Sussex, UK
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Silverleaf Shiny Stuff

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #26 on: May 12, 2011, 09:28:43 PM »
You know you might be able to fix those cracks, so make them a bit less noticable. I've done this with some large beads - you just warm them up in the oven again, get some ice water or a cold running tap, squeeze really hard to close up the crack and hold in the water. Keep squeezing until the beads's cool or you fingers are about to drop off, whichever's first! ;)

You could still see the cracks in my beads when I'd finished but they were just tiny hairlines ones rather than the huge gaping holes they were before.

Or you could smear in some Bake and Bond or ordinary clay mixed with liquid clay, like grout, and rebake.

KMD

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #27 on: May 12, 2011, 10:18:07 PM »
Good Tips!

OMG  :-[  Ok so my test came out perfect, my oven fluxs a lot, I baked clay at 130 it spiked to 145!!!! I turned it down and baked between 130 and 140 Result flexible bendable flat pieces Perfect for my keyrings!!!

Thank you Emma for giving me a kick I really dont know why I had 110 in my head!!!

Thankyou :-*
Karen 

shelleym

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #28 on: May 12, 2011, 10:18:19 PM »
Anna - I must admit i was thinking of mixing in some clay 'grout' of some description. Seeing as the design already has lots of black lines all over the place, little lines wouldn't be that noticeable. I think I even have some black tlc somewhere that I've never used! I've tried re-baking and squeezing them and also the ice bath - didn't make a blind bit of difference. If I do anything with them it'll have to be backfilling or grouting or something similar to disguise them. I've got a lot of other things to do, so that's not going to be priority at the mo. Just lesson learned - check what I put in my mixes and watch the temperature.
Shelley

KMD

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Re: Talking of Maggie Maggio - Polymer Clay Chain tutorial
« Reply #29 on: May 12, 2011, 10:22:39 PM »
by the way Your pendant looks lovely Shelley, cracks and all!