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Author Topic: Brittle clay  (Read 9679 times)

jewelray

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Re: Brittle clay
« Reply #15 on: June 09, 2014, 10:50:05 PM »
Thank yo for the info Carrie.  Must get some and try it on these beads. Will let you know what success I have.  RayM

The Indignant Bunny

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Re: Brittle clay
« Reply #16 on: June 27, 2014, 02:52:31 AM »
That's a great tip Karolina,


I have often had problems with brittleness in clay (if I'm baking a thin piece). Nowadays I bake my clay for an hour at 100 degrees Celsius, as I've found that baking it at a lower temperature for a longer period of time seems to make my pieces a little bit stronger. That's just my personal experience though.


I still make thinner pendants for earrings and such, but a lot of what I make now is generally much chunkier than when I first started using polymer clay. I'm definitely going to try the coat of TLS on some thinner pieces this week. :)

ejralph

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Re: Brittle clay
« Reply #17 on: June 27, 2014, 08:45:15 AM »
Are you using an independant oven thermometer when baking?

Because 100 degrees is a little on the cool side for clay to bake properly. So I wonder if actually by increasing the time to an hour, your oven is actually getting hotter and hitting that magical 110-130 degree window? Or if your oven runs a little hot anyway?

Usually if you were to bake at 100 degrees, it wouldn't really be quite hot enough to ensure a full baking and I'd expect the clay to be quite weak.

Emma

Emma from Sunny Sussex, UK
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Cara Jane

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Re: Brittle clay
« Reply #18 on: August 15, 2014, 05:03:29 PM »
Hi

I have never found Premo to be brittle. You can take a thin sheet of properly cured Premo and bend it right in half - fold back the other way - squashing the crease and repeat without damage. The key being 'properly cured!'

I had a halogen oven for a while but I found that the temperature fluctuates too much. It overheats and then cools down to below the temperature you want and then overheats again (all ovens do this to some degree but often it is very small fluctuations). I found that I had a lot more problems with cracking too.  I'd do a dry run (with no clay in it) and watch the thermometer.  The other thing would be to take some sample bits of clay - the same sort of size and shape as you are having trouble with but from scrap clay and try changing the time/temperature and see how strong it is.

Hope you find a solution - nothing worse than spending time making something for it to break too easily

Cara
Cara Jane Hayman - UK Polymer Clay Artist and Tutor
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ejralph

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Re: Brittle clay
« Reply #19 on: August 15, 2014, 05:57:52 PM »
Oh I have tested it very well - different ovens, different thermometers etc. so I know just what you mean about temp fluctuations. Thankfully my halogen is excellent and the most stable oven I've ever had. It is just I don't find modern Premo as strong as it used to be and definitely not as strong as Cernit.

But this it the thing with clay - everyone has different experiences and mileage really does vary.

I had an issue with the reformulated Fimo when it changed a few years back because of the phthalates thing. Try as I might, I couldn't bake balls of the reformulated Fimo at 130 without it cracking. Sheets no problem - they were lovely and strong, but balls would crack and craze.

 My customers were having no issue on the whole - only one or two found the same as me. Now I've been claying a long time and I am no rookie when it comes to working through a baking problem. I tried different ovens, different thermometers, different baking times - you name it, I tried it.  I even had the guy come in and calibrate the kitchen oven and tried that. Went totally over-the-top in trying to prove / disprove this one but I never did get that formulation to happily bake at 130 other than in thin sheets. In the end just chalked it up to experience as one of those things and figured maybe there was a reason why the manufacturers changed the baking temp to the lower 110 afterall. Life was  just too short to keep working the problem endlessly.

This is why I think new clayers should really try every clay though - because we all have different favourites. What would be quite a boring and lacklustre clay for one can be the bee's knees for the next person and really suit their working style. It is those subtle differences that make or break it for everyone. Also, its important to keep an eye on our fave clays as it isn't always apparent when they change formulations unless they give it away like Fimo did by having a different baking temp.

Have to say though, loving the new Fimo Professional and had no problems baking that one.

Emma



Emma from Sunny Sussex, UK
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ejralph

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Re: Brittle clay
« Reply #20 on: August 30, 2014, 07:51:12 PM »
Interesting round of experiments from Garie Sim on his blog recently. He was testing the strength of polymer clays with wires embedded. He baked clay logs with a wire embedded and then tried to bend them into a U shape after baking

Some of the clays he was testing I am not familiar with. Results were much as I expected for the clays I do know - Fimo Classic did well, but Premo, Fimo Soft and Sculpey all cracked.

Pity he didn't have the new Fimo Professional or Cernit to test - but it would be an interesting experiment to do sometime

http://claypolymer.blogspot.sg/2014/08/testing-all-clay-with-armature-wires-at.html

Emma



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BBCrafts

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Re: Brittle clay
« Reply #21 on: September 05, 2014, 04:54:41 PM »
I am thinking after finishing out my abundant amounts of Fimo Soft(I chose it over premo, because premo was to soft when conditioned.) Switching over to Either Cernit, Or Fimo Pro. I am thinking I am gonna ask my mom to buy me A pack of each from Emma. To test and play with. We shall see, Unfortunately I think I might stick with Fimo soft though, Due to me knowing the colours better.
Call Me Becka *Smiley Face*
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Sylvia

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Re: Brittle clay
« Reply #22 on: September 05, 2014, 05:23:42 PM »
I know!  Having done all my colour experiments in Fimo Soft and having a drawer full of colour chips, I'm so reluctant to move brands and have to do it over again.
Chalfont St Giles, Bucks, UK

ejralph

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Re: Brittle clay
« Reply #23 on: September 09, 2014, 11:12:53 AM »
The Fimo professional will probably be less of a leap colour-wise from Fimo Soft than the Cernit will.

Cernit will be quite an adjustment - very different colours and they behave differently too due to their semi-translucent nature, darkening / intensifying somewhat on baking. I adore Cernit - it really is right up my alley for a number of reasons. I am quite lazy on colour mixing though and find myself using a lot of their colours straight out of the packet. By the time I've embellished with my Illuminare techniques anyway, the end effect is very different so that works perfectly for me and there is a HUGE range of colours with cernit.

The Fimo professional is well worth trying out though if you are into mixing custom colours. The consistency is very nice and easy to condition whilst still containing some "body" to it as you work. baked strength is very good - far better than fimo Soft. The colours are nicely saturated - more so than Fimo Soft / Effect colours. Also their line of "true" colours is a joy for colour-mixing.

I'm certainly looking forward to playing around more with the Fimo professional colours.

Emma

Emma from Sunny Sussex, UK
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BBCrafts

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Re: Brittle clay
« Reply #24 on: September 09, 2014, 05:34:16 PM »
Well I am gonna try some different techniques, I am gonna to see if my michaels carries fimo Pro yet and if so grab my fav colors and play like crazy.
Call Me Becka *Smiley Face*
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ejralph

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Re: Brittle clay
« Reply #25 on: September 09, 2014, 08:55:53 PM »
Good idea. Try their True Blue, True Magenta and True Yellow. In theory, you should be able to mix practically anything with those plus some white and maybe a dash of black

Emma
Emma from Sunny Sussex, UK
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