Saturday, May 24, 2008

Playing with Liquid Clays

I've been experimenting with liquid clays recently, trying different brands and mixing different substances into them.  I've used Translucent Liquid Sculpey (TLS) a lot, especially for "gluing" baked clay to baked clay, but it isn't as clear as I want for a project I'm working on using sort of a cloissonne effect.  I'm looking for clear, vibrant colors to use for translucent butterfly wings and I want some subtle variations in colors.  To figure out what to use for my project, I compared Fimo Gel with Kato Clear Medium.

 Fimo Gel starts out the clearest and is wonderfully clear after baking at normal temperatures, i.e. the 265° specified on the bottle.  I was disappointed with Kato Clear when baked at 275°, the temperature specified on the bottle, and even after using a heat gun on it.  But then I read a paper about Kato Liquid that was handed out by Tony Aquino of Van Aken at the Synergy Conference.  "When cured at 275° it will give you a flat finish.  The recommended curing temperature is 300° for 20 minutes.  This temperature will result in a matte finish.  To increase gloss and clarity, cure an additional 10 minutes at 350° or wave a heat gun over the area until gloss is achieved."  When I followed this procedure, I got a nice glossy and clear result  with the Kato Medium.  

I found some "artist's pigments" at a local store and tried mixing them into the liquid clays. These are "no name" pigments from China and I don't think they are ground as finely as some more expensive ones may be.  I got a nice clear yellow and a bright red when mixed with both Kato and Fimo liquids, but the blues were grainy and mixing two pigments did not produce very nice secondary colors.  I found that oil paints worked very well although some of them were more opaque than others.  There are lots of colors and they blend very well, so I could get a nice range of hues.  Pinata Inks are very translucent and some of the colors really pop, but the color range is limited.  I had problems with bubbling when I baked the clay right after mixing, but letting them sit for a couple of hours until the alcohol evaporates seems to solve that problem.

When I tried making my butterfly wings (small example in the first photo), I found that the Fimo Gel was difficult to get into the tiny spaces formed by the black ribs where they come together.  I used a toothpick to apply the liquid clay, and although the Kato tended to drip, it flowed very easily into the smallest spaces.  The Fimo Gel wings had some problems with bubbles, although I haven't had that problem in the past when I applied the clear gel with a brush.  

It turns out that all three liquid clays have their advantages and I will probably use them all for different purposes.  TLS is great glue.  Fimo Gel works very well as a clear sealer over mica powders and gold leaf and does not have to be baked at high temperatures, making it safe to use with translucent clay.  Kato blends well, flows into small spaces and had no bubble problems, but having to bake at 350° or use a heat gun at the same temperature could cause problems in some situations.

In my next post, I'll show you my prototype butterflies.  And in the future, when I can get hold of some Kato Color Liquid Clay, I will see how that compares to my homemade mixes.

Tuesday, May 20, 2008

I'm Published!

Hooray.  One of my photos from Synergy was published in the current Polymer Cafe!  It's on page 57.  

Monday, May 12, 2008


Here is the link to find Google Reader:

Blog Readers

I had never heard of a blog reader until a couple of months ago, and now I can't do without one.  Instead of going to each individual blog to see if there is anything new and instead of having separate RSS feeds for each one, I subscribe to my blogs through Google Reader.  There are other readers out there, but this is the one I know, and it is easy to use.  I can group the blogs by subject matter and it automatically tells me which ones have new posts and shows the first part of the post in a window.  For short posts, I don't even have to go directly to the blog. The highlighted blogs in the image below have new posts.

 This link will take you to a tour of Google Reader.  Then you can set up a free Google account, if you don't have one already, and follow instructions.

Saturday, May 10, 2008

Great Glass Bead Artist

I found the most wonderful glass bead artist!  OK, she's my sister, Melissa Blanton, but her beads are great.  You can find her work by searching eBay for "lmg lampwork"  (the lmg is for Laurel Mountain Glass).  Here are some samples.

Friday, May 2, 2008

Testing Leached Premo

There has been some discussion in clay circles recently about the necessity to leach the new, softer formulation of Premo, and what, if any, effect leaching has on the strength of the clay. I decided to do a test. I took a big chunk of black Premo from a large block dated January 2008. It was quite soupy, so I'm sure it is the new formulation. I conditioned the clay by putting it through my pasta machine several times to make sure the chemicals were evenly distributed, and then I divided the clay in half. I leached one half by rolling it to #3 on my pasta machine (#1 is the thickest) and then put it between sheets of white paper. I rubbed the top sheet gently and then put a light weight on top. Then I let it sit overnight until 10 am the next morning. There was a lot of oily residue on the paper in the morning.

Next I thoroughly conditioned both the leached and unleached clay by putting it through the PM about 30 times. The leached clay cracked when I folded it and the sides were very ragged at first, but at the end of conditioning, it no longer cracked when folded.

I cut strips 1" by 5" at the #1 setting (thickest), #4 setting and #6 setting. It was easy to get a very thin strip of the leached clay, but the unleached was so sticky, it wouldn't roll flat. I got waves in it. Then I thought it would be interesting to see what would happen between the two extremes, so I blended the left over clay and made strips that were half leached and half unleached and then some that had a small amount of unleached clay added in to the leached. (3 and 1/2 parts leached and 1/2 part unleached.) This would simulate what you would do if you felt you had over-leached the clay and added some fresh clay back in. I had enough of this mixed clay to make strips at the #1 and #4 thicknesses. I baked the strips on tiles, at the same time and all at the same level in my convection oven, for 25 minutes at 285 degrees F. I wanted to be sure that the temperature met and slightly exceeded the 275 degree threshold suggested by the manufacturer. The strips were allowed to cool in the oven for several hours while I went to a movie.

First I tried bending the strips by touching one end to the other. I did that 50 times to the leached clay at all three thicknesses and they showed no wear or tear. I bent the thickest strip 50 times in the opposite direction and it was fine. That test wasn't going to show anything useful unless I spent a week doing nothing but bending clay so I tried something more extreme.

I bent about an inch of the strip back on itself and pinched the fold as tight as I could using both thumbs and forefingers. Then I bent it in the opposite direction and pinched the fold again (much tighter than in this photo). I kept doing this until the strip tore, and I tried to apply the same pressure each time. If leaching weakens the clay, I would expect to see a progression: the less leached, the more bends it would take to tear the clay.

Here's what happened:
Number of bends until the strip tore all the way across
First trial at #4 thickness
...Leached................... 1 bend until break
...Mostly leached .....20 bends
...Half and half.......... 5
...Unleached ..............25

Second trial at #4 thickness
...Leached ..................4
...Mostly leached .....25
...Half and half .........22
...Unleached .............33

Trial at #1 thickness (the thickest)
...Leached................... 2
...Mostly leached....... 7
...Half and half .........21
...Unleached.............. 37

Clearly, at both thicknesses, the fully leached clay breaks much faster than the unleached clay when subjected to extreme bending pressure. The thickest strips showed the progression I expected, but the results for the thinner (#4 thickness) strips was strange. The clay that was 3.5 parts leached to .5 parts unleached performed better than the clay that was half and half. I can't explain that. I mixed the clay thoroughly before making the strips. Perhaps the pressure I applied wasn't uniform.

For the very thinnest strips (#6), the leached clay broke after 14 bends and the unleached was still fine after 45 bends. No cracking at all. I didn't have intermediate samples at this thickness.

This bending test subjected the clay to stresses that probably would not be found in real life, so I tried whacking the different strips against the edge of my desk to simulate what might happen during shipping or if an item was dropped. None of them broke or chipped. Tests of objects with different shapes would be necessary to see what might happen during shipping of a sculpture, for example.

So, what does this tell us? Well, leaching makes Premo less able to withstand flexing, i.e., it is more brittle. For something like a cuff bracelet, less leaching is better. But for other objects not likely to be subject to such stresses, leaching may be acceptable. The question remains, how much is OK for a particular application and how do you control the amount of leaching that takes place? Is there a critical point where it goes from acceptable to not acceptable and how do you know where that is?