This blog is moving. I will no longer update this blog, although I will leave it here for the time being.
Please follow me over to my new blog address -www.carajane.co.uk
Please, please, please sign up to follow me there- I will feel lonely without you all!
I have moved all the content, including comments over from this blog, it will be the same blog just in a different place, and with a new header.
Thank you for all your enthusiasm and support!
Cara
Saturday, June 4, 2011
Thursday, June 2, 2011
Curing experiments part 2 - with videos!
So in part 1 I discovered that for optimum strength you should turn your oven off at the end of the curing cycle and leave your polymer clay pieces to cool down slowly in the cooling oven. This was just an initial test to see if the set up was going to work before I made lots of samples with more complicated curing, and something I had always been curious about. I was happy that the test worked and set about making more samples (got a blister from the extruder - am thinking it might be time to look at those walnut hollow ones....).
For these tests I chose to cool all my samples at room temperature, although I knew they would be stronger if I let them cool slowly. It was easier to control the curing, meaning I didn't have to reheat the oven for each curing and also the testing would be quicker if the specimens weren't as strong There will be a third round of tests where I search for the real optimum curing based on what I have learnt so far. As before samples are all made from very well conditioned scrap Kato polymer clay. They are extruded cylinders and are approximately 10 cm long and 6mm in diameter. You may note, looking at the results below, that I only repeated each test twice this time. I made three samples each time but as the results were reasonably close and there were a lot to test I decided that two was enough! I haven't got round to polishing the samples yet, to see how shine is affected by cure time/temp - that's a job for another day!
Cure time tests
I tried curing samples for different amounts of time. The temperature for all the samples was 150°C and they were removed from the oven at the end of their cure time to cool at room temperature. The samples cured for 40 min had some longitudinal cracks on them when they were removed from the oven, however there was no sign of the cracks when they had cooled.
Cure time results
10 min -breaking point weight - 501g, 481g
20 min - 2035g*, 1986g*
40 min - 1900g*, 1935g*
*weight of water when specimen bent out of jig.
The weights given for the 20 and 40 min cure samples are not particularly relevant as these samples didn't break, they curved so much they slipped through the test rig. You can see this happening and the test set up in the video below.
Having looked at the samples I conclude that for 6mm thick pieces 20 minutes curing is sufficient for strength and perhaps 40 min is too much due to the presence of the cracks on the warm sample, although this wasn't proved to make them weaker.
Oven temperature tests
All samples had 10 min in the oven at a set temperature that was verified with an oven thermometer, they were then removed and cooled at room temperature.
Increasing the cure temperature increased the strength of the sample significantly but the samples still all broke. Increasing the cure time meant that the samples were much stronger and held about 2kg, or 2 litres of water before they bent so much they slipped through the test jig. That may be to do with the increased time allowing the temperature in centre of the specimen to reach the correct temperature or some other factor, I'm not sure.
I would like to do some more tests looking at cure time against thickness of specimen so that I would know the ideal time for all thickness of clay. Next time I am bored I guess!
I will cure my next specimens at 160oC (320F) for 20 min, and leave them to cool in the oven as it cools down. This would seem to be the best way to cure 6mm thick Kato Polyclay for optimum strength. I will test this and let you know the results.
This blog will soon be finding a new home, I do hope you'll move with me - I'll keep you posted
Have fun with your polymer clay
Cara
For these tests I chose to cool all my samples at room temperature, although I knew they would be stronger if I let them cool slowly. It was easier to control the curing, meaning I didn't have to reheat the oven for each curing and also the testing would be quicker if the specimens weren't as strong There will be a third round of tests where I search for the real optimum curing based on what I have learnt so far. As before samples are all made from very well conditioned scrap Kato polymer clay. They are extruded cylinders and are approximately 10 cm long and 6mm in diameter. You may note, looking at the results below, that I only repeated each test twice this time. I made three samples each time but as the results were reasonably close and there were a lot to test I decided that two was enough! I haven't got round to polishing the samples yet, to see how shine is affected by cure time/temp - that's a job for another day!
Cure time tests
I tried curing samples for different amounts of time. The temperature for all the samples was 150°C and they were removed from the oven at the end of their cure time to cool at room temperature. The samples cured for 40 min had some longitudinal cracks on them when they were removed from the oven, however there was no sign of the cracks when they had cooled.
Cure time results
10 min -breaking point weight - 501g, 481g
20 min - 2035g*, 1986g*
40 min - 1900g*, 1935g*
*weight of water when specimen bent out of jig.
The weights given for the 20 and 40 min cure samples are not particularly relevant as these samples didn't break, they curved so much they slipped through the test rig. You can see this happening and the test set up in the video below.
Video showing the test set up and how the strong samples bent and slipped out of test jig.
Oven temperature tests
All samples had 10 min in the oven at a set temperature that was verified with an oven thermometer, they were then removed and cooled at room temperature.
Oven temp results
140°C (~280F)- breaking point weight -440g, 380g
150°C (~300F) - breaking point weight -501g, 481g
160°C (~320F)- breaking point weight -1076g, 900g
170°C (~338F)- breaking point weight -1567g, 1498g
As you can see that change from 150°C to 160°C and again to 170°C makes a significant increase in strength!
Here's a video of a 140°C sample so you can see how little it flexed before breaking, compared to the 150°C for 20 min sample in the video above.
Video showing a test where the 140°C for 10 min cure specimen breaks without much bend
In a recent post on the Kato facebook page (31st March if you want to look back and find it, can't find a way to make a direct link to that post) Tony Aquino, the technical director at Van Aken, who manufacture Kato polyclay, discussed curing temperatures (great timing thank you Tony!). He said that higher temperature of curing would mean stronger clay, my tests show this too.
Conclusion of my experiments so far
Increasing the cure temperature increased the strength of the sample significantly but the samples still all broke. Increasing the cure time meant that the samples were much stronger and held about 2kg, or 2 litres of water before they bent so much they slipped through the test jig. That may be to do with the increased time allowing the temperature in centre of the specimen to reach the correct temperature or some other factor, I'm not sure.
I would like to do some more tests looking at cure time against thickness of specimen so that I would know the ideal time for all thickness of clay. Next time I am bored I guess!
I will cure my next specimens at 160oC (320F) for 20 min, and leave them to cool in the oven as it cools down. This would seem to be the best way to cure 6mm thick Kato Polyclay for optimum strength. I will test this and let you know the results.
This blog will soon be finding a new home, I do hope you'll move with me - I'll keep you posted
Have fun with your polymer clay
Cara
Thursday, May 26, 2011
Special pen
It's my husband Richy's 40th birthday today. Hopefully he is having fun at work while I bake his cake and prepare a special meal for dinner!
He got lots of presents from me and the children but here's one I wanted to share with you.
He got lots of presents from me and the children but here's one I wanted to share with you.
Rhodium plated pen with polymer clay decoration
The pen looking all fancy in it's presentation box
You may remember I made a pen for my mum recently, from a fairly average pen kit and I was really chuffed at how great it looked compared to covering a biro. Well this was a fancy pen kit, rhodium plated no less. It cost more than I would normally dream of spending on a pen but it was for my wonderful husbands 40th birthday. It looks great it has a real air of quality about it and the parts went together much more easily! I particularly like that the barrel is in one part so only 1 part to cover and there's no band in the middle so you could shape the barrel if you wanted (although straight is easy!). With the 2 barrel pens if you don't get the thickness just right it can look a bit odd. I ordered a few more of the cheaper pen kits when I ordered this but I think I shall spend a little more and get a better quality kit to work with in future, they do plain chrome ones the same as this which are much more reasonably priced.
Right back to my baking.....
Monday, May 23, 2011
Beaux Bangles with Carol Blackburn
I was lucky enough to attend a workshop with the lovely Carol Blackburn yesterday. The workshop was organised by Clectic Events (Rebecca Thickbroom) so I knew it would be well organised, and indeed it was! It was great to spend time with so many lovely people. To catch up with some people I now consider old friends and to meet some new friends too! And even better I get to see a lot of them again this Sunday at the London Polymer Clay Group Meeting .
I haven't got long to write this post as I am preparing for my husbands 40th birthday on Thursday (i.e. making all the stuff I meant to make for him weeks ago but...) so I shall show you what I made (quickly snapped photos too - sorry).
I made 2 bangles in the workshop, although I had to finish bits of both of them at home today.
The first bangle I made I used Fimo, as the workshop was being sponsored by them and we had been given some blocks. I used to work with Fimo soft until they reformulated it and it became too soft for my liking, then I swapped to Kato and have never looked back. I have sanded it but it doesn't feel as nice as the Kato and I found it too sticky and squishy when I was working with it. It does smell better though! I really like one part of the bangle - this bit here
it's a neat looking pattern and I like the spread of colours. And I really don't like this bit
it looks kind of smeared and messy and the colours don't work. The structure of it is good and sturdy and I like the technique Carol showed us.
The stripy one is a lot more chunky than the first one and has a core of sculpey ultralight (thanks Toni for providing it!) so it isn't much heavier. It was the first time I have worked with sculpey ultra light, and possibly the last, it's like marshmallow! The rest of the bangle is made with Kato clay. It needed more sanding at the middle stage really but I rushed it as I wanted to get it covered in the class so the outer profile is a little lumpy and bumpy and not the best shape. It's quite a striking piece of jewellery though and you don't see the lumps and bumps.
I've done some more baking experiments (which I will report when I have a moment) so I hope with my new knowledge from Carol's workshop and my experiments I can make strong skinny bangles too. Can't wait to try out some more big bangles but it will have to wait, birthdays and then school holidays - hmm perhaps my children would like to make some too! My 6 year old son loves to make jewellery for his girlfriends, will have to find a child size bangle form!
The Ripple Effect is another Carol Blackburn/Celctic Events workshop happening in London on the 21st August. I can't make that one unfortunately but I've seen the sample pieces and they look great!
I haven't got long to write this post as I am preparing for my husbands 40th birthday on Thursday (i.e. making all the stuff I meant to make for him weeks ago but...) so I shall show you what I made (quickly snapped photos too - sorry).
The first bangle I made I used Fimo, as the workshop was being sponsored by them and we had been given some blocks. I used to work with Fimo soft until they reformulated it and it became too soft for my liking, then I swapped to Kato and have never looked back. I have sanded it but it doesn't feel as nice as the Kato and I found it too sticky and squishy when I was working with it. It does smell better though! I really like one part of the bangle - this bit here
it's a neat looking pattern and I like the spread of colours. And I really don't like this bit
it looks kind of smeared and messy and the colours don't work. The structure of it is good and sturdy and I like the technique Carol showed us.
The stripy one is a lot more chunky than the first one and has a core of sculpey ultralight (thanks Toni for providing it!) so it isn't much heavier. It was the first time I have worked with sculpey ultra light, and possibly the last, it's like marshmallow! The rest of the bangle is made with Kato clay. It needed more sanding at the middle stage really but I rushed it as I wanted to get it covered in the class so the outer profile is a little lumpy and bumpy and not the best shape. It's quite a striking piece of jewellery though and you don't see the lumps and bumps.
I've done some more baking experiments (which I will report when I have a moment) so I hope with my new knowledge from Carol's workshop and my experiments I can make strong skinny bangles too. Can't wait to try out some more big bangles but it will have to wait, birthdays and then school holidays - hmm perhaps my children would like to make some too! My 6 year old son loves to make jewellery for his girlfriends, will have to find a child size bangle form!
The Ripple Effect is another Carol Blackburn/Celctic Events workshop happening in London on the 21st August. I can't make that one unfortunately but I've seen the sample pieces and they look great!
Sunday, May 15, 2011
Curing experiments part 1
In order to find out how best to make strong bracelets I have a series of experiments planned. The first thing I wanted to find out was if polymer clay is stronger if it's quenched, that is plunged into ice cold water straight from the oven. I've heard people say this makes it stronger, polish better and it will keep transparents more transparent. Well I'm using grey coloured scrap Kato clay so can't comment on the transparency but my findings were that it doesn't make clay stronger or polish better.
I wanted to know how strong polymer clay was when it was being bent so my clever engineer husband set up a test for me. I used to do similar work with composite materials for a living as a research materials scientist but I had big expensive machines and gauges to record what was happening (I've got a photo somewhere I will try and dig it out). My husband has also done similar work (we met at work) but is better at finding alternative ways to do things than I am, he's a real problem solver!
Here is one of my extruded rod samples, of extremely well conditioned Kato scrap clay. They are 10cm long and about 6mm in diameter. I chose to extrude them so I could be sure they were as similar as possible.
The sample is 'bridged' over a gap. A loop of ribbon is passed over it and attached to an empty milk carton. Water is poured into the carton until the samples breaks and then we weighed how much water the sample had 'held'. My husband tried to poor the water into the bottle at a steady rate, he isn't holding the bottle just has his hand under it to catch it when the sample breaks so the water doesn't spill. We weighed the water in the bottle at the point that each sample broke.
One of the test pieces not long before it broke! As you can see it has bent quite a bit.
All the test pieces were baked at 150°C (verified with oven thermometer) for 10 min. At this point
three samples were taken out of the oven and left on the side to cool, I am calling these samples 'room temperature'. Three were plunged into ice water, I am calling these samples 'quenched' and three were left to cool in the oven which was turned off and cooling down slowing, these are called 'slow cool' samples.
The results
'Quenched' samples breaking point weight - 485g, 673g, 772g
'Room temperature' breaking point weight -501g, 481g, 759g
'Slow cool' samples breaking point weight- 1069g, 1274g, 1522g
As you can see although there is a fair bit of variation in the results without a doubt the 'slow cool' samples were significantly stronger in flexure (being bent). Watching the test they obviously bent a lot more than the other 2 types of samples before snapping. I'll try and video one of the next ones so you can see a test in action.
I then polished one part of each type of sample using my micromesh cloths and counting the strokes, doing the same for each. The verdict on that is that there is no discernible difference in shine between them.
This test was with Kato clay, I am curious if it's true for other polymer clays but being as I don't use other brands I probably won't take the time to find out I'm afraid.
I am going to do two more tests one to see how the baking temperature effects the strength in flexure (bending) and shine and one to see how the baking time effects the strength in flexure and shine. I am pretty sure that the longer baking time will make them more shiny when polished as that is one of the reasons I currently bake for longer, it will be interesting to find out in a more controlled way though.
The results may be a while coming so in the meantime I would advise that if you want your clay strong, leave it to cool down in the oven after turning it off when you have finished baking!
I wanted to know how strong polymer clay was when it was being bent so my clever engineer husband set up a test for me. I used to do similar work with composite materials for a living as a research materials scientist but I had big expensive machines and gauges to record what was happening (I've got a photo somewhere I will try and dig it out). My husband has also done similar work (we met at work) but is better at finding alternative ways to do things than I am, he's a real problem solver!
Here is one of my extruded rod samples, of extremely well conditioned Kato scrap clay. They are 10cm long and about 6mm in diameter. I chose to extrude them so I could be sure they were as similar as possible.
The sample is 'bridged' over a gap. A loop of ribbon is passed over it and attached to an empty milk carton. Water is poured into the carton until the samples breaks and then we weighed how much water the sample had 'held'. My husband tried to poor the water into the bottle at a steady rate, he isn't holding the bottle just has his hand under it to catch it when the sample breaks so the water doesn't spill. We weighed the water in the bottle at the point that each sample broke.
All the test pieces were baked at 150°C (verified with oven thermometer) for 10 min. At this point
three samples were taken out of the oven and left on the side to cool, I am calling these samples 'room temperature'. Three were plunged into ice water, I am calling these samples 'quenched' and three were left to cool in the oven which was turned off and cooling down slowing, these are called 'slow cool' samples.
The results
'Quenched' samples breaking point weight - 485g, 673g, 772g
'Room temperature' breaking point weight -501g, 481g, 759g
'Slow cool' samples breaking point weight- 1069g, 1274g, 1522g
As you can see although there is a fair bit of variation in the results without a doubt the 'slow cool' samples were significantly stronger in flexure (being bent). Watching the test they obviously bent a lot more than the other 2 types of samples before snapping. I'll try and video one of the next ones so you can see a test in action.
I then polished one part of each type of sample using my micromesh cloths and counting the strokes, doing the same for each. The verdict on that is that there is no discernible difference in shine between them.
This test was with Kato clay, I am curious if it's true for other polymer clays but being as I don't use other brands I probably won't take the time to find out I'm afraid.
I am going to do two more tests one to see how the baking temperature effects the strength in flexure (bending) and shine and one to see how the baking time effects the strength in flexure and shine. I am pretty sure that the longer baking time will make them more shiny when polished as that is one of the reasons I currently bake for longer, it will be interesting to find out in a more controlled way though.
The results may be a while coming so in the meantime I would advise that if you want your clay strong, leave it to cool down in the oven after turning it off when you have finished baking!
Friday, May 13, 2011
Blogger down - lost post - bangle problems
I guess many of you bloggers know that blogger has been down for a while (since last night for me in the UK). It made me realise that I have no other record of the information in my blog as I wanted to check back on my - things I want to make post to remind me and couldn't access it. Can you back up blogs? Must investigate.
Also I wrote a long wordy post on bangle problems - blogger has probably chosen not to publish it cause it was too long and boring! I will try and summarise it this time round.
I have trouble making solid polymer clay bangles, the often seem to break easily. At first they seemed to break at the join so I now add a bit of polypaste and make sure I smooth the seams carefully. That solved the popping at the seams but now means they break elsewhere instead! See evidence below
These were made from very well conditioned Kato scrap clay extruded through the largest makins D shape die (about 8mm wide and about 5mm at it's thickest). Joined carefully with some polypaste, baked on an empty coke can at 150 oC (300F) for 40 mins. They broke when I was carefully sliding them from the coke can, the first break was not at the join. Glad they broke then rather than after I had taken the time to cover them I suppose!
This bangle is made from a sausage of well conditioned Kato clay joined carefully with some polypaste in the join, covered with a decorated sheet of cane slices, baked on an empty coke can at 150oC for 1 hour. It looked fine and felt strong so I wore it for a morning. All good until I decided to sand it. Almost the minute I started gently sanding with my soft micromesh cloth draped over my fingers it broke. It is quite skinny, about 8mm in diameter, like some others I have been wearing which are fine - here's a post about them.
So where am I going wrong with them? My husband has a feeling that baking them for a long time they are strong but brittle and I should under cure them rather than cure them for longer so they are more ductile, less brittle. I was about to start some baking trials for different times when I came across a post from Tony Aquino on the Kato Polyclay Facebook page stating that the higher the cure temperature the stronger the clay will be. I will try and test some different temperatures too. What I need for bangles is something with a little flex I guess. I've had a few suggestions from clever people at the PCC Forum to try out. I will report back with anything I find out, but please leave a comment or mail me if you have any ideas I could try to make bangles that don't break!
thanks
Cara
Also I wrote a long wordy post on bangle problems - blogger has probably chosen not to publish it cause it was too long and boring! I will try and summarise it this time round.
I have trouble making solid polymer clay bangles, the often seem to break easily. At first they seemed to break at the join so I now add a bit of polypaste and make sure I smooth the seams carefully. That solved the popping at the seams but now means they break elsewhere instead! See evidence below
So where am I going wrong with them? My husband has a feeling that baking them for a long time they are strong but brittle and I should under cure them rather than cure them for longer so they are more ductile, less brittle. I was about to start some baking trials for different times when I came across a post from Tony Aquino on the Kato Polyclay Facebook page stating that the higher the cure temperature the stronger the clay will be. I will try and test some different temperatures too. What I need for bangles is something with a little flex I guess. I've had a few suggestions from clever people at the PCC Forum to try out. I will report back with anything I find out, but please leave a comment or mail me if you have any ideas I could try to make bangles that don't break!
thanks
Cara
Monday, May 9, 2011
Purple Flowers,pendants, micromesh and pens
My mum got more birthday presents made by me. I wasn't quite sure how my disc necklace would work out so I went back to something I knew would work just in case - a flowery cabochon. Again in purples. It turned out very well, I'm very pleased with it. She ended up with both.
I recently bought some new micromesh sheets in the 8000 and 12000 grits. Previously I had the basic hobby kit which went up to 6000. The difference in the shine is marked. Polishing up to 12000 grit micromesh means that you can buff to a glass like shine by hand on a tea towel! Add a little mechanical buffing on the dremel and they are glorious! With this one I made the cabochon (hand formed) then I baked and polished it then added the frame and rebaked. I polished again through the last 3 grades briefly and then buffed. It certainly doesn't look like polymer clay any more!
I also made my first proper pen, with a pen kit rather than covering a cheap biro. Again for my mum, she was a little spoilt I think, but she deserves it!
In theory it's refillable but I had some trouble fitting the parts together so I am not sure how easily it will come apart to put refill in. Again it's polished with the new finer micromesh cloths and it's a thing of purple beauty! I wish I had made my polymer clay bits a tiny bit thinner so it doesn't bulge out from the central band. Next time I will - or I'll just cover the band with a different clay pattern too! I've ordered some more pen kits so watch this space for more. I have ordered some different types to try out. There are so many different ones out there it's hard to know which ones to buy.
I've made some other jewellery bits with the same 2 purple flower canes. As always I didn't make the canes big enough, if I didn't like them I would have lots of it of course! Sometimes canes just really turn out great. With these I love how the colours work together but because I wasn't sure if using all purples would be too much I only made very small canes. Luckily I am getting good at cutting thin so I have made them go a long way.
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