Author Topic: Uro polymer clay review  (Read 27512 times)

Offline jeff_lamarche

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Re: Uro polymer clay review
« Reply #45 on: January 22, 2012, 05:58:12 PM GMT GMT »
In the manufacturer's website says that the baking time is 20 or 30 minutes at 130º. Time for Super Sculpey Firm is 15 minutes at the same temperature.
[snip]
Noticed that if you keep the figure in the oven more than 15 minutes the Super Sculpey firm burns.

Although I haven't done much work at this scale, I've done a fair bit with polymer clay at larger sizes, and "how to bake" polymer clays is a bet of a contested topics. There seems to be two schools of thought that I categorize in my head as the "Steak" and "Barbecue" schools. The "Steak" school of thought basically says that you use a high temperature and shorter time - as high as you can go without releasing dangerous gases.  This is the school of thought that is used for the instructions on most polymer clays. It's usually given as 130°C or 270°F, which is about as high as you can safely go in a conventional oven, which often has a variance of up to 10°C / 50°F.

The other school of thought is the "barbecue" school, which uses a lower temperature, just enough over the boiling point of water to account for heat variance - about 110°C / 230°F. This is the actual temperature needed to harden the clay, but the kicker is, you have to get the clay in the center up to that temperature. That's why they recommend the higher temperature, not because you need the higher temperature to achieve fusion. What that means is that with the lower temperature, have to bake for at least 3-4 times the recommended time to make sure the center gets up to temperature (less for thinner or smaller pieces, more for larger ones). What I do for larger pieces (6" - 10" tall) is bake for 4 or even 5 times the recommended duration, then turn off the oven and leave the piece in the oven until the oven has returned to room temperature (I often bake at the end of the day and leave it in the oven overnight). In my experience, the slower cool down significantly reduces the likelihood of cracks. An abrupt change of temperature, such as from taking the piece out of the oven into room temperature is one of the greatest contributing factors to cracks and other problems.

The benefit of the "barbecue" approach is that the piece is unlikely to scorch or overcook (which can turn the piece brittle and in extreme cases can cause the release of dangerous chlorine gas). There's almost no danger or downside from over baking with barbecue. The downside of the "barbecue" method is that you have to be much more patient.
For minis, I primarily work in putty, not in polymer clay, so I can't tell you how this information applies to this scale exactly, but I thought it was worth sharing.

Offline Andrew May

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Re: Uro polymer clay review
« Reply #46 on: January 22, 2012, 11:56:53 PM GMT GMT »
Well.........
What I do with Uro and other clays is put the sculpt in and bring the oven (household, electric, fan-assisted) up to 125c from cold then hold that temp for only 5mins and then turn off the heat (leaving the fan on) and leave the door ajar until it's pretty much cool again. There's only usually a few mm to bake in a mini sculpt and I find that the gradual heating and cooling prevents cracking esp as I use an epoxy core.
I hope that makes sense!

Offline Viper1959

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Re: Uro polymer clay review
« Reply #47 on: January 23, 2012, 01:14:51 AM GMT GMT »
Well.........
What I do with Uro and other clays is put the sculpt in and bring the oven (household, electric, fan-assisted) up to 125c from cold then hold that temp for only 5mins and then turn off the heat (leaving the fan on) and leave the door ajar until it's pretty much cool again. There's only usually a few mm to bake in a mini sculpt and I find that the gradual heating and cooling prevents cracking esp as I use an epoxy core.
I hope that makes sense!

Andrew, is that what you did with the Protoceratops?
exellent sculpt bye the way!


Dave.

Offline Andrew May

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Re: Uro polymer clay review
« Reply #48 on: January 23, 2012, 08:48:44 AM GMT GMT »
Yes, sculpted in Uro and same baking procedure, I think that one was baked 3 or 4 times in total with no problems. The trick is to time how long your oven takes to reach the desired temp (mine takes just shy of 10mins) and the set your timer fir that plus 5min that way you're not staring at the oven all day! While the oven is cooling the fan is getting rid of any vapour and you can get on with another job.

Offline Burano

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Re: Uro polymer clay review
« Reply #49 on: January 23, 2012, 04:00:22 PM GMT GMT »
Thank you very much for all the info! It is very useful =)

I'll do a test, more time at lower temperature and publish the results.

Offline Viper1959

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Re: Uro polymer clay review
« Reply #50 on: January 31, 2012, 12:43:48 PM GMT GMT »
Ok, I finaly started a sculpt with URO and I find its wonderful stuff to work with, also you can take your time, not having limited working time as with air drying putty.

I also like the way that, the more you condition it, the softer and stickier it becomes.

There is definately a big similarity to Greenstuff when sculpting it, much more than I thought?

To bake it, I have been removing the sculpt from the cork, Now I have what might seem a stupid Question?....

Can you bake the sculpt on the cork, or does the cork burn at that temperature?


Dave.

Offline Andrew May

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Re: Uro polymer clay review
« Reply #51 on: February 02, 2012, 08:00:30 AM GMT GMT »
Natural cork will be fine at that temp, I do it most days!

Offline Viper1959

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Re: Uro polymer clay review
« Reply #52 on: February 03, 2012, 12:57:02 AM GMT GMT »
Quote
Natural cork will be fine at that temp, I do it most days!

Thanks Andrew...

Offline Heresy Miniatures

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Re: Uro polymer clay review
« Reply #53 on: February 07, 2012, 10:45:04 AM GMT GMT »
Have been giving this a go over the weekend - it has pros and cons - the first con is the amount of effort it takes to get the stuff pliable! Blimey, not sure how one would go about doing a giant or similar in this, the working is a killer!

The main pro is that you can, once you're got the clay softened, do huge areas of musculature etc very quickly indeed. Great for that, love it. Have also done a 4x size skull. However, I've had no luck with faces yet - the putty seems to be too soft for my ham-fisted epoxy techniques, but will keep trying and see how I get on.

Which leaves me my biggest problem with it so far - fragility! Basically, this stuff seems to crumble and flake with the slightest provocation - am I not baking it hard enough? Does it get tougher with a hotter bake? I swear I gave the skull a harsh look and the jaw snapped away.

Offline Andrew May

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Re: Uro polymer clay review
« Reply #54 on: February 07, 2012, 12:29:33 PM GMT GMT »
Quote
Well.........
What I do with Uro and other clays is put the sculpt in and bring the oven (household, electric, fan-assisted) up to 125c from cold then hold that temp for only 5mins and then turn off the heat (leaving the fan on) and leave the door ajar until it's pretty much cool again. There's only usually a few mm to bake in a mini sculpt and I find that the gradual heating and cooling prevents cracking esp as I use an epoxy core.

What are you doing re baking Andy? I've never had problems with fragility, except when I tried to do fine fingers without a wire inside.

Offline ink the troll

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Re: Uro polymer clay review
« Reply #55 on: February 07, 2012, 03:41:12 PM GMT GMT »
(...) The main pro is that you can, once you're got the clay softened, do huge areas of musculature etc very quickly indeed. Great for that, love it. Have also done a 4x size skull. However, I've had no luck with faces yet - the putty seems to be too soft for my ham-fisted epoxy techniques, but will keep trying and see how I get on. (...)
Try letting it 'set' a bit. After applying the clay in roughly the form you want, go make some tea and drink that. Then go back to add the details (works for fimo, so I guess it should pretty much be true for most brands of clay).

Kneading:
Only ever tried that with Fimo, but here's what I use if I really need to knead large amounts of that stuff: http://minisculpture.co.uk/index.php?topic=218.0
Clay gets a little warm, and thus too soft to work with it immediately though.
sanity is for cowards
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Offline Andrew May

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Re: Uro polymer clay review
« Reply #56 on: February 07, 2012, 03:54:57 PM GMT GMT »
Also I should point out that I have freakishly hot hands.

Offline Heresy Miniatures

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Re: Uro polymer clay review
« Reply #57 on: February 08, 2012, 09:59:55 AM GMT GMT »
Well, in all honesty I'm currently baking it using my desklamps as I can't be bothered with the whole oven thing at home, it takes ages to warm up and costs a bomb- the lamps get hot enough to melt sturdy plastic things, so seem to be hot enough to solidify the clay enough to work on it further without leaving fingerprints etc. I've no idea what temp they achieve, but it's certainly hot enough to burn your finger if you pick up some metal that's been under them.

If you're saying the clay gets real tough from an oven bake, I guess I'll have to go with that after all!

Offline ink the troll

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Re: Uro polymer clay review
« Reply #58 on: February 08, 2012, 12:26:55 PM GMT GMT »
Well, in all honesty I'm currently baking it using my desklamps as I can't be bothered with the whole oven thing at home, it takes ages to warm up and costs a bomb- the lamps get hot enough to melt sturdy plastic things, so seem to be hot enough to solidify the clay enough to work on it further without leaving fingerprints etc. I've no idea what temp they achieve, but it's certainly hot enough to burn your finger if you pick up some metal that's been under them.

If you're saying the clay gets real tough from an oven bake, I guess I'll have to go with that after all!
Definitely try oven baking your sculpts. There's also toaster ovens, consider buying a cheap one, if and when funds allow. They use less energy than a normal oven and are thus more cost efficent- makes only sense buying one for minis though if you're planning to sculpt a lot in polymer clay (or of course if you also want a small oven for pizza and such).
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Offline Heresy Miniatures

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Re: Uro polymer clay review
« Reply #59 on: February 08, 2012, 12:34:56 PM GMT GMT »
Got one at work, we use it to warm the moulds prior to casting.